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Wikipedia

Seahorse

January 20, 2023

This article is about the genus of fish. For the creature in mythology, see Hippocampus (mythology). For other uses, see Seahorse (disambiguation).

A seahorse (also written sea-horse and sea horse) is any of 46 species of small marine fish in the genus Hippocampus. "Hippocampus" comes from the Ancient Greek hippókampos (ἱππόκαμπος), itself from híppos (ἵππος) meaning "horse" and kámpos (κάμπος) meaning "sea monster"[4][5] or "sea animal".[6] Having a head and neck suggestive of a horse, seahorses also feature segmented bony armour, an upright posture and a curled prehensile tail.[7] Along with the pipefishes and seadragons (Phycodurus and Phyllopteryx) they form the family Syngnathidae.

Seahorses
Temporal range: Lower Miocene to present – 23–0 Ma
Short-snouted seahorse (Hippocampus hippocampus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Syngnathiformes
Family: Syngnathidae
Subfamily: Hippocampinae
Genus: Hippocampus
Rafinesque, 1810[1][2]
Type species
Hippocampus heptagonus
Rafinesque, 1810
Species

see Species.

Synonyms

Habitat

Seahorses are mainly found in shallow tropical and temperate salt water throughout the world, from about 45°S to 45°N.[8] They live in sheltered areas such as seagrass beds, estuaries, coral reefs, and mangroves. Four species are found in Pacific waters from North America to South America. In the Atlantic, Hippocampus erectus ranges from Nova Scotia to Uruguay. H. zosterae, known as the dwarf seahorse, is found in the Bahamas.

Colonies have been found in European waters such as the Thames Estuary.[9]

Three species live in the Mediterranean Sea: H. guttulatus (the long-snouted seahorse), H. hippocampus (the short-snouted seahorse), and H. fuscus (the sea pony). These species form territories; males stay within 1 m2 (10 sq ft) of habitat, while females range over about one hundred times that.

Description

 
Spiny seahorse H. histrix from East Timor holding on to soft coral with its prehensile tail
 
H. jayakari

Seahorses range in size from 1.5 to 35.5 cm (5⁄8 to 14 in).[10] They are named for their equine appearance, with bent necks and long snouted heads and a distinctive trunk and tail. Although they are bony fish, they do not have scales, but rather thin skin stretched over a series of bony plates, which are arranged in rings throughout their bodies. Each species has a distinct number of rings.[11] The armor of bony plates also protects them against predators,[12] and because of this outer skeleton, they no longer have ribs.[13] Seahorses swim upright, propelling themselves using the dorsal fin, another characteristic not shared by their close pipefish relatives, which swim horizontally. Razorfish are the only other fish that swim vertically. The pectoral fins, located on either side of the head behind their eyes, are used for steering. They lack the caudal fin typical of fishes. Their prehensile tail is composed of square-like rings that can be unlocked only in the most extreme conditions.[14] They are adept at camouflage, and can grow and reabsorb spiny appendages depending on their habitat.[15]

Unusually among fish, a seahorse has a flexible, well-defined neck. It also sports a crown-like spine or horn on its head, termed a "coronet", which is distinct for each species.[16]

Seahorses swim very poorly, rapidly fluttering a dorsal fin and using pectoral fins to steer. The slowest-moving fish in the world is H. zosterae (the dwarf seahorse), with a top speed of about 1.5 m (5 ft) per hour.[17] Since they are poor swimmers, they are most likely to be found resting with their prehensile tail wound around a stationary object. They have long snouts, which they use to suck up food, and their eyes can move independently of each other like those of a chameleon.[18]

Evolution and fossil record

Anatomical evidence, supported by molecular, physical, and genetic evidence, demonstrates that seahorses are highly modified pipefish. The fossil record of seahorses, however, is very sparse. The best known and best studied fossils are specimens of Hippocampus guttulatus (though literature more commonly refers to them under the synonym of H. ramulosus), from the Marecchia River formation of Rimini Province, Italy, dating back to the Lower Pliocene, about 3 million years ago. The earliest known seahorse fossils are of two pipefish-like species, H. sarmaticus and H. slovenicus, from the coprolitic horizon of Tunjice Hills, a middle Miocene lagerstätte in Slovenia dating back about 13 million years.[19]

Molecular dating implies that pipefish and seahorses diverged during the Late Oligocene. This has led to speculation that seahorses evolved in response to large areas of shallow water, newly created as the result of tectonic events. The shallow water would have allowed the expansion of seagrass habitats that served as camouflage for the seahorses' upright posture.[20] These tectonic changes occurred in the western Pacific Ocean, pointing to an origin there, with molecular data suggesting two later, separate invasions of the Atlantic Ocean.[21] In 2016, a study published in Nature found the seahorse genome to be the most rapidly evolving fish genome studied so far.[22]

The evolution of seahorses from pipefish may have been an adaptation related to the biomechanics of prey capture. The unique posture of the seahorse allows them to capture small shrimps at larger distances than the pipefish is capable of.[23]

Reproduction

See also: Animal sexual behavior § Seahorse
 
Seahorse life-cycle

The male seahorse is equipped with a brood pouch on the ventral, or front-facing, side of the tail. When mating, the female seahorse deposits up to 1,500 eggs in the male's pouch. The male carries the eggs for 9 to 45 days until the seahorses emerge fully developed, but very small. The young are then released into the water, and the male often mates again within hours or days during the breeding season.[24]

Courtship

Before breeding, seahorses may court for several days. Scientists believe the courtship behavior synchronizes the animals' movements and reproductive states, so that the male can receive the eggs when the female is ready to deposit them. During this time, they may change color, swim side by side holding tails or grip the same strand of sea grass with their tails, and wheel around in unison in what is known as a "predawn dance". They eventually engage in a "true courtship dance" lasting about 8 hours, during which the male pumps water through the egg pouch on his trunk which expands and opens to display its emptiness. When the female's eggs reach maturity, she and her mate let go of any anchors and drift upward snout-to-snout, out of the sea grass, often spiraling as they rise. They interact for about 6 minutes, reminiscent of courtship. The female then swims away until the next morning, and the male returns to sucking up food through his snout.[25] The female inserts her ovipositor into the male's brood pouch and deposits dozens to thousands of eggs. As the female releases her eggs, her body slims while his swells. Both animals then sink back into the sea grass and she swims away.[26]

Phases of courtship

Seahorses exhibit four phases of courtship that are indicated by clear behavioral changes and changes in the intensity of the courtship act. Phase 1, the initial courtship phase, typically takes place in the early morning one or two days before physical copulation. During this phase the potential mates brighten in colour, quiver, and display rapid side-to-side body vibrations. These displays are performed alternately by both the male and the female seahorse. The following phases, 2 through 4, happen sequentially on the day of copulation. Phase 2 is marked by the female pointing, a behaviour in which the female will raise her head to form an oblique angle with her body. In phase 3 males will also begin the same pointing behaviour in response to the female. Finally, the male and female will repeatedly rise upward together in a water column and end in mid-water copulation, in which the female will transfer her eggs directly into the male's brood pouch.[27]

Phase 1: Initial courtship

This initial courtship behaviour takes place about 30 minutes after dawn on each courtship day, until the day of copulation. During this phase the males and females will remain apart during the night, but after dawn they will come together in a side-by-side position, brighten, and engage in courtship behaviour for about 2 to 38 minutes. There is repeated reciprocal quivering. This starts when the male approaches the female, brightens and begins to quiver. The female will follow the male with her own display, in which she will also brighten and quiver about 5 seconds later. As the male quivers, he will rotate his body towards the female who will then rotate her body away. During phase 1 the tails of both seahorses are positioned within 1 cm of each other on the same hold-fast and both of their bodies are angled slightly outward from the point of attachment. However, the female will shift her tail attachment site, causing the pair to circle their common hold-fast.[27]

Phase 2: Pointing and pumping

This phase begins with the female beginning her pointing posture, by leaning her body towards the male, who will simultaneously lean away and quiver. This phase can last up to 54 minutes. Following phase 2 is a latency period (typically between 30 minutes and four hours), during which the seahorses display no courtship behaviour and females are not bright; males will usually display a pumping motion with their body.[27]

Phase 3: Pointing – pointing
 
Seahorses in Phase 2 of courtship

The third phase begins with the females brightening and assuming the pointing position. The males respond with their own brightening and pointing display. This phase ends with the male departing. It usually lasts nine minutes and can occur one to six times during courtship.[27]

Phase 4: Rising and copulation

The final courtship phase includes 5-8 bouts of courtship. Each bout of courtship begins with both the male and female anchored to the same plant about 3 cm apart; usually they are facing each other and are still bright in colour from the previous phase. During the first bout, following the facing behaviour, the seahorses will rise upward together anywhere from 2 to 13 cm in a water column. During the final rise the female will insert her ovipositor and transfer her eggs though an opening into the male's brood pouch.[27]

Fertilization

During fertilization in Hippocampus kuda the brood pouch was found to be open for only six seconds while egg deposition occurred. During this time seawater entered the pouch where the spermatozoa and eggs meet in a seawater milieu. This hyperosmotic environment facilitates sperm activation and motility. The fertilization is therefore regarded as being physiologically ‘external’ within a physically ‘internal’ environment after the closure of the pouch.[28] It is believed that this protected form of fertilization reduces sperm competition among males. Within the Syngnathidae (pipefishes and seahorses) protected fertilization has not been documented in the pipefishes but the lack of any distinct differences in the relation of testes size to body size suggests that pipefishes may also have evolved mechanisms for more efficient fertilization with reduced sperm competition.[29]

Gestation

 
Seahorses in Phase 4 of courtship

The fertilized eggs are then embedded in the pouch wall and become surrounded by a spongy tissue.[30] The male supplies the eggs with prolactin, the same hormone responsible for milk production in pregnant mammals.[citation needed] The pouch provides oxygen,[31] as well as a controlled environment incubator. Though the egg yolk contributes nourishment to the developing embryo, the male sea horses contribute additional nutrients such as energy-rich lipids and also calcium to allow them to build their skeletal system, by secreting them into the brood pouch that are absorbed by the embryos. Further they also offer immunological protection, osmoregulation, gas exchange and waste transport.[32]

The eggs then hatch in the pouch, where the salinity of the water is regulated; this prepares the newborns for life in the sea.[25][33][34] Throughout gestation, which in most species requires two to four weeks, his mate visits him daily for “morning greetings”.

Birth

The number of young released by the male seahorse averages 100–1000 for most species, but may be as low as 5 for the smaller species, or as high as 2,500.[30] When the fry are ready to be born, the male expels them with muscular contractions. He typically gives birth at night and is ready for the next batch of eggs by morning when his mate returns. Like almost all other fish species, seahorses do not nurture their young after birth. Infants are susceptible to predators or ocean currents which wash them away from feeding grounds or into temperatures too extreme for their delicate bodies. Less than 0.5% of infants survive to adulthood, explaining why litters are so large. These survival rates are actually fairly high compared to other fish, because of their protected gestation, making the process worth the great cost to the father. The eggs of most other fish are abandoned immediately after fertilization.[34]

Reproductive roles

 
Diagram of a pregnant male seahorse (Hippocampus comes) [22]
 
Pregnant male seahorse at the New York Aquarium

Reproduction is energetically costly to the male. This brings into question why the sexual role reversal even takes place. In an environment where one partner incurs more energy costs than the other, Bateman's principle suggests that the lesser contributor takes the role of the aggressor. Male seahorses are more aggressive and sometimes “fight” for female attention. According to Amanda Vincent of Project Seahorse, only males tail-wrestle and snap their heads at each other. This discovery prompted further study of energy costs. To estimate the female's direct contribution, researchers chemically analyzed the energy stored in each egg. To measure the burden on the males, oxygen consumption was used. By the end of incubation, the male consumed almost 33% more oxygen than before mating. The study concluded that the female's energy expenditure while generating eggs is twice that of males during incubation, confirming the standard hypothesis.[25]

Why the male seahorse (and other members of the Syngnathidae) carries the offspring through gestation is unknown, though some researchers believe it allows for shorter birthing intervals, in turn resulting in more offspring.[35] Given an unlimited number of ready and willing partners, males have the potential to produce 17% more offspring than females in a breeding season. Also, females have “time-outs” from the reproductive cycle 1.2 times longer than those of males. This seems to be based on mate choice, rather than physiology. When the female's eggs are ready, she must lay them in a few hours or eject them into the water column. Making eggs is a huge cost to her physically, since they amount to about a third of her body weight. To protect against losing a clutch, the female demands a long courtship. The daily greetings help to cement the bond between the pair.[36]

Monogamy

Though seahorses are not known to mate for life, many species form pair bonds that last through at least the breeding season. Some species show a higher level of mate fidelity than others.[37][38] However, many species readily switch mates when the opportunity arises. H. abdominalis and H. breviceps have been shown to breed in groups, showing no continuous mate preference. Many more species' mating habits have not been studied, so it is unknown how many species are actually monogamous, or how long those bonds actually last.[39]

Although monogamy within fish is not common, it does appear to exist for some. In this case, the mate-guarding hypothesis may be an explanation. This hypothesis states, “males remain with a single female because of ecological factors that make male parental care and protection of offspring especially advantageous.”[40] Because the rates of survival for newborn seahorses are so low, incubation is essential. Though not proven, males could have taken on this role because of the lengthy period the females require to produce their eggs. If males incubate while females prepare the next clutch (amounting to a third of body weight), they can reduce the interval between clutches.[citation needed]

Feeding habits

 
Seahorses rely on stealth to ambush small prey such as copepods. They use pivot feeding to catch the copepod, which involves rotating their snout at high speed and then sucking in the copepod.[41]

Seahorses use their long snouts to eat their food with ease. However, they are slow to consume their food and have extremely simple digestive systems that lack a stomach, so they must eat constantly to stay alive.[42] Seahorses are not very good swimmers, and for this reason they need to anchor themselves to seaweed, coral or anything else that will anchor the seahorse in place. They do this by using their prehensile tails to grasp their object of choice.[43] Seahorses feed on small crustaceans floating in the water or crawling on the bottom. With excellent camouflage seahorses ambush prey that floats within striking range, sitting and waiting until an optimal moment.[42] Mysid shrimp and other small crustaceans are favorites, but some seahorses have been observed eating other kinds of invertebrates and even larval fish. In a study of seahorses, the distinctive head morphology was found to give them a hydrodynamic advantage that creates minimal interference while approaching an evasive prey. Thus the seahorse can get very close to the copepods on which it preys.[41][44] After successfully closing in on the prey without alerting it, the seahorse gives an upward thrust and rapidly rotates the head aided by large tendons that store and release elastic energy, to bring its long snout close to the prey. This step is crucial for prey capture, as oral suction only works at a close range. This two-phase prey capture mechanism is termed pivot-feeding.[44][45] Seahorses have three distinctive feeding phases: preparatory, expansive, and recovery. During the preparatory phase, the seahorse slowly approaches the prey while in an upright position, after which it slowly flexes its head ventrally. In the expansive phase, the seahorse captures its prey by simultaneously elevating its head, expanding the buccal cavity, and sucking in the prey item. During the recovery phase, the jaws, head, and hyoid apparatus of the seahorse return to their original positions.[46]

The amount of available cover influences the seahorse's feeding behaviour. For example, in wild areas with small amounts of vegetation, seahorses will sit and wait, but an environment with extensive vegetation will prompt the seahorse to inspect its environment, feeding while swimming rather than sitting and waiting. Conversely, in an aquarium setting with little vegetation, the seahorse will fully inspect its environment and makes no attempt to sit and wait.[47]

 
Seahorse hiding using camouflage

Threats of extinction

Because data is lacking on the sizes of the various seahorse populations, as well as other issues including how many seahorses are dying each year, how many are being born, and the number used for souvenirs, there is insufficient information to assess their risk of extinction, and the risk of losing more seahorses remains a concern. Some species, such as the Paradoxical Seahorse, H. paradoxus, may already be extinct.[citation needed] Coral reefs and seagrass beds are deteriorating, reducing viable habitats for seahorses.[48] Additionally, bycatch in many areas causes high cumulative effects on seahorses, with an estimated 37 million individuals being removed annually over 21 countries.[49]

Aquaria

While many aquarium hobbyists keep them as pets, seahorses collected from the wild tend to fare poorly in home aquaria. Many eat only live foods such as brine shrimp and are prone to stress, which damages their immune systems and makes them susceptible to disease.[citation needed]

In recent years, however, captive breeding has become more popular. Such seahorses survive better in captivity, and are less likely to carry diseases. They eat frozen mysidacea (crustaceans) that are readily available from aquarium stores,[50] and do not experience the stress of moving out of the wild. Although captive-bred seahorses are more expensive, they take no toll on wild populations.

Seahorses should be kept in an aquarium with low flow and placid tank mates. They are slow feeders, so fast, aggressive feeders will leave them without food.[50] Seahorses can coexist with many species of shrimp and other bottom-feeding creatures. Gobies also make good tank-mates. Keepers are generally advised to avoid eels, tangs, triggerfish, squid, octopus, and sea anemones.[51]

Water quality is very important for the survival of seahorses in an aquarium. They are delicate species which should not be added to a new tank. The water parameters are recommended to be as follows although these fish may acclimatise to different water over time:

  • Temperature: 23–28 °C (73–82 °F)
  • pH: 8.1–8.4
  • Ammonia: 0 mg/L (0 ppm) (0.01 mg/L (0.01 ppm) may be tolerated for short periods)
  • Nitrite: 0 mg/L (0 ppm) (0.125 mg/L (0.125 ppm) may be tolerated for short periods)
  • S.G.: 1.021–1.024 at 23–24 °C (73–75 °F)[citation needed]

A water-quality problem will affect fish behaviour and can be shown by clamped fins, reduced feeding, erratic swimming, and gasping at the surface.[52] Seahorses swim up and down, as well as using the length of the aquarium. Therefore, the tanks should ideally be twice as deep as the length of the adult seahorse.[citation needed]

Animals sold as "freshwater seahorses" are usually the closely related pipefish, of which a few species live in the lower reaches of rivers. The supposed true "freshwater seahorse" called H. aimei is not a valid species, but a synonym sometimes used for Barbour's and hedgehog seahorses. The latter, which is often confused with the former, can be found in estuarine environments, but is not actually a freshwater fish.[53]

Use in Chinese medicine

 
Dried seahorse
 
Seahorse and scorpion skewers as street food

Seahorse populations are thought to be endangered as a result of overfishing and habitat destruction. Despite a lack of scientific studies or clinical trials,[54][55] the consumption of seahorses is widespread in traditional Chinese medicine, primarily in connection with impotence, wheezing, nocturnal enuresis, and pain, as well as labor induction.[56] Up to 20 million seahorses may be caught each year to be sold for such uses.[57] Preferred species of seahorses include H. kellogii, H. histrix, H. kuda, H. trimaculatus, and H. mohnikei.[56] Seahorses are also consumed by Indonesians, central Filipinos, and many other ethnic groups[citation needed].

Import and export of seahorses has been controlled under CITES since 15 May 2004. However, Indonesia, Japan, Norway, and South Korea have chosen to opt out of the trade rules set by CITES.

The problem may be exacerbated by the growth of pills and capsules as the preferred method of ingesting seahorses. Pills are cheaper and more available than traditional, individually tailored prescriptions of whole seahorses, but the contents are harder to track. Seahorses once had to be of a certain size and quality before they were accepted by TCM practitioners and consumers. Declining availability of the preferred large, pale, and smooth seahorses has been offset by the shift towards prepackaged preparations, which makes it possible for TCM merchants to sell previously unused, or otherwise undesirable juvenile, spiny, and dark-coloured animals. Today, almost a third of the seahorses sold in China are packaged, adding to the pressure on the species.[58] Dried seahorse retails from US$600 to $3000 per kilogram, with larger, paler, and smoother animals commanding the highest prices. In terms of value based on weight, seahorses retail for more than the price of silver and almost that of gold in Asia.[59]

Species

Based on the newest overall taxonomic review[60] of the genus Hippocampus with further new species and partial taxonomic review,[61][62][63][64] the number of recognized species in this genus is considered to be 46 (retrieved May 2020):

 
H. kuda, known as the "common seahorse"
 
H. subelongatus, known as the "West Australian seahorse"
 
H. whitei, known as "White's seahorse"

Pygmy seahorses

Main article: Hippocampinae
 
Hippocampus satomiae (Satomi's pygmy seahorse) attached to coral

Pygmy seahorses are those members of the genus that are less than 15 mm (9⁄16 in) tall and 17 mm (11⁄16 in) wide. Previously the term was applied exclusively to the species H. bargibanti but since 1997, discoveries have made this usage obsolete. The species H. minotaur, H. denise, H. colemani, H. pontohi, H. severnsi, H. satomiae, H. waleananus, H. nalu, H. japapigu have been described. Other species that are believed to be unclassified have also been reported in books, dive magazines and on the Internet. They can be distinguished from other species of seahorse by their 12 trunk rings, low number of tail rings (26–29), the location in which young are brooded in the trunk region of males and their extremely small size.[65] Molecular analysis (of ribosomal RNA) of 32 Hippocampus species found that H. bargibanti belongs in a separate clade from other members of the genus and therefore that the species diverged from the other species in the ancient past.[66]

Most pygmy seahorses are well camouflaged and live in close association with other organisms including colonial hydrozoans (Lytocarpus and Antennellopsis), coralline algae (Halimeda) sea fans (Muricella, Annella, Acanthogorgia). This combined with their small size accounts for why most species have only been noticed and classified since 2001.[65][67]

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  34. ^ a b Danielson, Stentor (14 June 2002). "Seahorse Fathers Take Reins in Childbirth". National Geographic News.
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  39. ^ Weiss, Tami (10 April 2010). "What's Love Got to Do With It? The Truth About Seahorse Monogamy". fusedjaw.com.
  40. ^ Alcock, John (2005). Animal Behavior (8th ed.). Massachusetts: Sinauer. pp. 370–1. ISBN 978-0878930050.
  41. ^ a b Langley, Liz (26 November 2013). "Why Does the Seahorse Have Its Odd Head? Mystery Solved – News Watch". Newswatch.nationalgeographic.com.
  42. ^ a b Woods, Chris M. C. (September 2002). "Natural diet of the seahorse Hippocampus abdominalis". New Zealand Journal of Marine and Freshwater Research. 36 (3): 655–660. doi:10.1080/00288330.2002.9517121. ISSN 0028-8330.
  43. ^ Flynn, A. J.; Ritz, D. A. (June 1999). "Effect of habitat complexity and predatory style on the capture success of fish feeding on aggregated prey". Journal of the Marine Biological Association of the United Kingdom. 79 (3): 487–494. doi:10.1017/s0025315498000617. ISSN 1469-7769. S2CID 86160386.
  44. ^ a b Gemmell, B. J.; Sheng, J.; Buskey, E. J. (2013). "Morphology of seahorse head hydrodynamically aids in capture of evasive prey". Nature Communications. 4: 2840. Bibcode:2013NatCo...4.2840G. doi:10.1038/ncomms3840. PMID 24281430.
  45. ^ Wassenbergh, Sam Van; Strother, James A.; Flammang, Brooke E.; Ferry-Graham, Lara A.; Aerts, Peter (6 March 2008). "Extremely fast prey capture in pipefish is powered by elastic recoil". Journal of the Royal Society Interface. 5 (20): 285–296. doi:10.1098/rsif.2007.1124. ISSN 1742-5689. PMC 2607401. PMID 17626004.
  46. ^ Bergert, B. A.; Wainwright, P. C. (14 March 1997). "Morphology and kinematics of prey capture in the syngnathid fishes Hippocampus erectus and Syngnathus floridae". Marine Biology. 127 (4): 563–570. doi:10.1007/s002270050046. ISSN 0025-3162. S2CID 84452341.
  47. ^ Rosa, Ierecê L.; Dias, Thelma L.; Baum, Julia K. (2002). "Threatened Fishes of the World: Hippocampus reidi Ginsburg, 1933 (Syngnathidae)". Environmental Biology of Fishes. 64 (4): 378. doi:10.1023/a:1016152528847. ISSN 0378-1909. S2CID 26782777.
  48. ^ Lourie, Sarah A.; Foster, Sarah J.; Cooper, Ernest W.T. and Vincent, Amanda C.J. (2004) A Guide to the Identification of Seahorses. Project Seahorse Advancing Marine Conservation, ISBN 0-89164-169-6.
  49. ^ Lawson, J. M.; Foster, S. J.; Vincent, A. C. J. (January 2017). "Low bycatch rates add up to big numbers for a genus of small fishes". Fisheries Magazine. American Fisheries Society. 42 (1): 19–33. doi:10.1080/03632415.2017.1259944.
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  60. ^ LOURIE, SARA A.; POLLOM, RILEY A.; FOSTER, SARAH J. (1 August 2016). "A global revision of the Seahorses Hippocampus Rafinesque 1810 (Actinopterygii: Syngnathiformes): Taxonomy and biogeography with recommendations for further research". Zootaxa. 4146 (1): 1–66. doi:10.11646/zootaxa.4146.1.1. ISSN 1175-5334. PMID 27515600.
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Further reading

  • Amanda C.J. Vincent & Laila M. Sadler (1995). "Faithful pair bonds in wild seahorse, Hippocampus whitei". Animal Behaviour. 50 (6): 1557–69. doi:10.1016/0003-3472(95)80011-5. S2CID 53192875.
  • Amanda C.J. Vincent (1995). "A role for daily greetings in maintaining seahorse pair bonds". Animal Behaviour. 49: 258–260. doi:10.1016/0003-3472(95)80178-2. S2CID 54391512.
  • Amanda C.J. Vincent (1990). "A seahorse father makes a good mother". Natural History. 12: 34–43.
  • Amanda C.J. Vincent & Rosie Woodroffe (1994). "Mothers little helpers: patterns of male care in mammals". Trends in Ecology and Evolution. 9 (8): 294–7. doi:10.1016/0169-5347(94)90033-7. PMID 21236858.
  • John Sparks (1999). Battle of the Sexes: The Natural History of Sex. London: BBC Books. ISBN 978-0-563-37145-8.
  • Sara A. Lourie, Amanda C.J. Vincent and Heather J. Hall (1999). Seahorses: An Identification Guide to the World's Species and their Conversation. London: Project Seahorse.
  • Teske, Peter R.; Hamilton, Healy; Matthee, Conrad A.; Barker, Nigel P. (15 August 2007). "Signatures of seaway closures and founder dispersal in the phylogeny of a circumglobally distributed seahorse lineage". BMC Evolutionary Biology. 7: 138. doi:10.1186/1471-2148-7-138. ISSN 1471-2148. PMC 1978501. PMID 17697373.

External links

 
Wikimedia Commons has media related to Seahorse.
 
Wikisource has the text of the 1911 Encyclopædia Britannica article "Sea-horse".

January 20, 2023
seahorse, this, article, about, genus, fish, creature, mythology, hippocampus, mythology, other, uses, disambiguation, seahorse, also, written, horse, horse, species, small, marine, fish, genus, hippocampus, hippocampus, comes, from, ancient, greek, hippókampo. This article is about the genus of fish For the creature in mythology see Hippocampus mythology For other uses see Seahorse disambiguation A seahorse also written sea horse and sea horse is any of 46 species of small marine fish in the genus Hippocampus Hippocampus comes from the Ancient Greek hippokampos ἱppokampos itself from hippos ἵppos meaning horse and kampos kampos meaning sea monster 4 5 or sea animal 6 Having a head and neck suggestive of a horse seahorses also feature segmented bony armour an upright posture and a curled prehensile tail 7 Along with the pipefishes and seadragons Phycodurus and Phyllopteryx they form the family Syngnathidae SeahorsesTemporal range Lower Miocene to present 23 0 Ma PreꞒ Ꞓ O S D C P T J K Pg NShort snouted seahorse Hippocampus hippocampus Scientific classificationKingdom AnimaliaPhylum ChordataClass ActinopterygiiOrder SyngnathiformesFamily SyngnathidaeSubfamily HippocampinaeGenus HippocampusRafinesque 1810 1 2 Type speciesHippocampus heptagonusRafinesque 1810Speciessee Species SynonymsAcentronura Kaup 1853 Farlapiscis Whitley 1931 3 Jamsus Ginsburg 1937 Macleayina Fowler 1907 Phyllopteryx Swainson 1839 Contents 1 Habitat 2 Description 3 Evolution and fossil record 4 Reproduction 4 1 Courtship 4 1 1 Phases of courtship 4 1 1 1 Phase 1 Initial courtship 4 1 1 2 Phase 2 Pointing and pumping 4 1 1 3 Phase 3 Pointing pointing 4 1 1 4 Phase 4 Rising and copulation 4 2 Fertilization 4 3 Gestation 4 4 Birth 4 5 Reproductive roles 4 6 Monogamy 5 Feeding habits 6 Threats of extinction 7 Aquaria 8 Use in Chinese medicine 9 Species 10 Pygmy seahorses 11 References 12 Further reading 13 External linksHabitat EditSeahorses are mainly found in shallow tropical and temperate salt water throughout the world from about 45 S to 45 N 8 They live in sheltered areas such as seagrass beds estuaries coral reefs and mangroves Four species are found in Pacific waters from North America to South America In the Atlantic Hippocampus erectus ranges from Nova Scotia to Uruguay H zosterae known as the dwarf seahorse is found in the Bahamas Colonies have been found in European waters such as the Thames Estuary 9 Three species live in the Mediterranean Sea H guttulatus the long snouted seahorse H hippocampus the short snouted seahorse and H fuscus the sea pony These species form territories males stay within 1 m2 10 sq ft of habitat while females range over about one hundred times that Description Edit Spiny seahorse H histrix from East Timor holding on to soft coral with its prehensile tail H jayakari Seahorses range in size from 1 5 to 35 5 cm 5 8 to 14 in 10 They are named for their equine appearance with bent necks and long snouted heads and a distinctive trunk and tail Although they are bony fish they do not have scales but rather thin skin stretched over a series of bony plates which are arranged in rings throughout their bodies Each species has a distinct number of rings 11 The armor of bony plates also protects them against predators 12 and because of this outer skeleton they no longer have ribs 13 Seahorses swim upright propelling themselves using the dorsal fin another characteristic not shared by their close pipefish relatives which swim horizontally Razorfish are the only other fish that swim vertically The pectoral fins located on either side of the head behind their eyes are used for steering They lack the caudal fin typical of fishes Their prehensile tail is composed of square like rings that can be unlocked only in the most extreme conditions 14 They are adept at camouflage and can grow and reabsorb spiny appendages depending on their habitat 15 Unusually among fish a seahorse has a flexible well defined neck It also sports a crown like spine or horn on its head termed a coronet which is distinct for each species 16 Seahorses swim very poorly rapidly fluttering a dorsal fin and using pectoral fins to steer The slowest moving fish in the world is H zosterae the dwarf seahorse with a top speed of about 1 5 m 5 ft per hour 17 Since they are poor swimmers they are most likely to be found resting with their prehensile tail wound around a stationary object They have long snouts which they use to suck up food and their eyes can move independently of each other like those of a chameleon 18 Evolution and fossil record EditAnatomical evidence supported by molecular physical and genetic evidence demonstrates that seahorses are highly modified pipefish The fossil record of seahorses however is very sparse The best known and best studied fossils are specimens of Hippocampus guttulatus though literature more commonly refers to them under the synonym of H ramulosus from the Marecchia River formation of Rimini Province Italy dating back to the Lower Pliocene about 3 million years ago The earliest known seahorse fossils are of two pipefish like species H sarmaticus and H slovenicus from the coprolitic horizon of Tunjice Hills a middle Miocene lagerstatte in Slovenia dating back about 13 million years 19 Molecular dating implies that pipefish and seahorses diverged during the Late Oligocene This has led to speculation that seahorses evolved in response to large areas of shallow water newly created as the result of tectonic events The shallow water would have allowed the expansion of seagrass habitats that served as camouflage for the seahorses upright posture 20 These tectonic changes occurred in the western Pacific Ocean pointing to an origin there with molecular data suggesting two later separate invasions of the Atlantic Ocean 21 In 2016 a study published in Nature found the seahorse genome to be the most rapidly evolving fish genome studied so far 22 The evolution of seahorses from pipefish may have been an adaptation related to the biomechanics of prey capture The unique posture of the seahorse allows them to capture small shrimps at larger distances than the pipefish is capable of 23 Reproduction EditSee also Animal sexual behavior Seahorse Seahorse life cycle The male seahorse is equipped with a brood pouch on the ventral or front facing side of the tail When mating the female seahorse deposits up to 1 500 eggs in the male s pouch The male carries the eggs for 9 to 45 days until the seahorses emerge fully developed but very small The young are then released into the water and the male often mates again within hours or days during the breeding season 24 Courtship Edit Before breeding seahorses may court for several days Scientists believe the courtship behavior synchronizes the animals movements and reproductive states so that the male can receive the eggs when the female is ready to deposit them During this time they may change color swim side by side holding tails or grip the same strand of sea grass with their tails and wheel around in unison in what is known as a predawn dance They eventually engage in a true courtship dance lasting about 8 hours during which the male pumps water through the egg pouch on his trunk which expands and opens to display its emptiness When the female s eggs reach maturity she and her mate let go of any anchors and drift upward snout to snout out of the sea grass often spiraling as they rise They interact for about 6 minutes reminiscent of courtship The female then swims away until the next morning and the male returns to sucking up food through his snout 25 The female inserts her ovipositor into the male s brood pouch and deposits dozens to thousands of eggs As the female releases her eggs her body slims while his swells Both animals then sink back into the sea grass and she swims away 26 Phases of courtship Edit Seahorses exhibit four phases of courtship that are indicated by clear behavioral changes and changes in the intensity of the courtship act Phase 1 the initial courtship phase typically takes place in the early morning one or two days before physical copulation During this phase the potential mates brighten in colour quiver and display rapid side to side body vibrations These displays are performed alternately by both the male and the female seahorse The following phases 2 through 4 happen sequentially on the day of copulation Phase 2 is marked by the female pointing a behaviour in which the female will raise her head to form an oblique angle with her body In phase 3 males will also begin the same pointing behaviour in response to the female Finally the male and female will repeatedly rise upward together in a water column and end in mid water copulation in which the female will transfer her eggs directly into the male s brood pouch 27 Phase 1 Initial courtship Edit This initial courtship behaviour takes place about 30 minutes after dawn on each courtship day until the day of copulation During this phase the males and females will remain apart during the night but after dawn they will come together in a side by side position brighten and engage in courtship behaviour for about 2 to 38 minutes There is repeated reciprocal quivering This starts when the male approaches the female brightens and begins to quiver The female will follow the male with her own display in which she will also brighten and quiver about 5 seconds later As the male quivers he will rotate his body towards the female who will then rotate her body away During phase 1 the tails of both seahorses are positioned within 1 cm of each other on the same hold fast and both of their bodies are angled slightly outward from the point of attachment However the female will shift her tail attachment site causing the pair to circle their common hold fast 27 Phase 2 Pointing and pumping Edit This phase begins with the female beginning her pointing posture by leaning her body towards the male who will simultaneously lean away and quiver This phase can last up to 54 minutes Following phase 2 is a latency period typically between 30 minutes and four hours during which the seahorses display no courtship behaviour and females are not bright males will usually display a pumping motion with their body 27 Phase 3 Pointing pointing Edit Seahorses in Phase 2 of courtship The third phase begins with the females brightening and assuming the pointing position The males respond with their own brightening and pointing display This phase ends with the male departing It usually lasts nine minutes and can occur one to six times during courtship 27 Phase 4 Rising and copulation Edit The final courtship phase includes 5 8 bouts of courtship Each bout of courtship begins with both the male and female anchored to the same plant about 3 cm apart usually they are facing each other and are still bright in colour from the previous phase During the first bout following the facing behaviour the seahorses will rise upward together anywhere from 2 to 13 cm in a water column During the final rise the female will insert her ovipositor and transfer her eggs though an opening into the male s brood pouch 27 Fertilization Edit During fertilization in Hippocampus kuda the brood pouch was found to be open for only six seconds while egg deposition occurred During this time seawater entered the pouch where the spermatozoa and eggs meet in a seawater milieu This hyperosmotic environment facilitates sperm activation and motility The fertilization is therefore regarded as being physiologically external within a physically internal environment after the closure of the pouch 28 It is believed that this protected form of fertilization reduces sperm competition among males Within the Syngnathidae pipefishes and seahorses protected fertilization has not been documented in the pipefishes but the lack of any distinct differences in the relation of testes size to body size suggests that pipefishes may also have evolved mechanisms for more efficient fertilization with reduced sperm competition 29 Gestation Edit Seahorses in Phase 4 of courtship The fertilized eggs are then embedded in the pouch wall and become surrounded by a spongy tissue 30 The male supplies the eggs with prolactin the same hormone responsible for milk production in pregnant mammals citation needed The pouch provides oxygen 31 as well as a controlled environment incubator Though the egg yolk contributes nourishment to the developing embryo the male sea horses contribute additional nutrients such as energy rich lipids and also calcium to allow them to build their skeletal system by secreting them into the brood pouch that are absorbed by the embryos Further they also offer immunological protection osmoregulation gas exchange and waste transport 32 The eggs then hatch in the pouch where the salinity of the water is regulated this prepares the newborns for life in the sea 25 33 34 Throughout gestation which in most species requires two to four weeks his mate visits him daily for morning greetings Birth Edit The number of young released by the male seahorse averages 100 1000 for most species but may be as low as 5 for the smaller species or as high as 2 500 30 When the fry are ready to be born the male expels them with muscular contractions He typically gives birth at night and is ready for the next batch of eggs by morning when his mate returns Like almost all other fish species seahorses do not nurture their young after birth Infants are susceptible to predators or ocean currents which wash them away from feeding grounds or into temperatures too extreme for their delicate bodies Less than 0 5 of infants survive to adulthood explaining why litters are so large These survival rates are actually fairly high compared to other fish because of their protected gestation making the process worth the great cost to the father The eggs of most other fish are abandoned immediately after fertilization 34 Reproductive roles Edit Diagram of a pregnant male seahorse Hippocampus comes 22 Pregnant male seahorse at the New York Aquarium Reproduction is energetically costly to the male This brings into question why the sexual role reversal even takes place In an environment where one partner incurs more energy costs than the other Bateman s principle suggests that the lesser contributor takes the role of the aggressor Male seahorses are more aggressive and sometimes fight for female attention According to Amanda Vincent of Project Seahorse only males tail wrestle and snap their heads at each other This discovery prompted further study of energy costs To estimate the female s direct contribution researchers chemically analyzed the energy stored in each egg To measure the burden on the males oxygen consumption was used By the end of incubation the male consumed almost 33 more oxygen than before mating The study concluded that the female s energy expenditure while generating eggs is twice that of males during incubation confirming the standard hypothesis 25 Why the male seahorse and other members of the Syngnathidae carries the offspring through gestation is unknown though some researchers believe it allows for shorter birthing intervals in turn resulting in more offspring 35 Given an unlimited number of ready and willing partners males have the potential to produce 17 more offspring than females in a breeding season Also females have time outs from the reproductive cycle 1 2 times longer than those of males This seems to be based on mate choice rather than physiology When the female s eggs are ready she must lay them in a few hours or eject them into the water column Making eggs is a huge cost to her physically since they amount to about a third of her body weight To protect against losing a clutch the female demands a long courtship The daily greetings help to cement the bond between the pair 36 Monogamy Edit Though seahorses are not known to mate for life many species form pair bonds that last through at least the breeding season Some species show a higher level of mate fidelity than others 37 38 However many species readily switch mates when the opportunity arises H abdominalis and H breviceps have been shown to breed in groups showing no continuous mate preference Many more species mating habits have not been studied so it is unknown how many species are actually monogamous or how long those bonds actually last 39 Although monogamy within fish is not common it does appear to exist for some In this case the mate guarding hypothesis may be an explanation This hypothesis states males remain with a single female because of ecological factors that make male parental care and protection of offspring especially advantageous 40 Because the rates of survival for newborn seahorses are so low incubation is essential Though not proven males could have taken on this role because of the lengthy period the females require to produce their eggs If males incubate while females prepare the next clutch amounting to a third of body weight they can reduce the interval between clutches citation needed Feeding habits Edit Seahorses rely on stealth to ambush small prey such as copepods They use pivot feeding to catch the copepod which involves rotating their snout at high speed and then sucking in the copepod 41 Seahorses use their long snouts to eat their food with ease However they are slow to consume their food and have extremely simple digestive systems that lack a stomach so they must eat constantly to stay alive 42 Seahorses are not very good swimmers and for this reason they need to anchor themselves to seaweed coral or anything else that will anchor the seahorse in place They do this by using their prehensile tails to grasp their object of choice 43 Seahorses feed on small crustaceans floating in the water or crawling on the bottom With excellent camouflage seahorses ambush prey that floats within striking range sitting and waiting until an optimal moment 42 Mysid shrimp and other small crustaceans are favorites but some seahorses have been observed eating other kinds of invertebrates and even larval fish In a study of seahorses the distinctive head morphology was found to give them a hydrodynamic advantage that creates minimal interference while approaching an evasive prey Thus the seahorse can get very close to the copepods on which it preys 41 44 After successfully closing in on the prey without alerting it the seahorse gives an upward thrust and rapidly rotates the head aided by large tendons that store and release elastic energy to bring its long snout close to the prey This step is crucial for prey capture as oral suction only works at a close range This two phase prey capture mechanism is termed pivot feeding 44 45 Seahorses have three distinctive feeding phases preparatory expansive and recovery During the preparatory phase the seahorse slowly approaches the prey while in an upright position after which it slowly flexes its head ventrally In the expansive phase the seahorse captures its prey by simultaneously elevating its head expanding the buccal cavity and sucking in the prey item During the recovery phase the jaws head and hyoid apparatus of the seahorse return to their original positions 46 The amount of available cover influences the seahorse s feeding behaviour For example in wild areas with small amounts of vegetation seahorses will sit and wait but an environment with extensive vegetation will prompt the seahorse to inspect its environment feeding while swimming rather than sitting and waiting Conversely in an aquarium setting with little vegetation the seahorse will fully inspect its environment and makes no attempt to sit and wait 47 Seahorse hiding using camouflage Seahorses Hippocampus erectus at the New England AquariumThreats of extinction EditBecause data is lacking on the sizes of the various seahorse populations as well as other issues including how many seahorses are dying each year how many are being born and the number used for souvenirs there is insufficient information to assess their risk of extinction and the risk of losing more seahorses remains a concern Some species such as the Paradoxical Seahorse H paradoxus may already be extinct citation needed Coral reefs and seagrass beds are deteriorating reducing viable habitats for seahorses 48 Additionally bycatch in many areas causes high cumulative effects on seahorses with an estimated 37 million individuals being removed annually over 21 countries 49 Aquaria EditThis section needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Seahorse news newspapers books scholar JSTOR January 2018 Learn how and when to remove this template message While many aquarium hobbyists keep them as pets seahorses collected from the wild tend to fare poorly in home aquaria Many eat only live foods such as brine shrimp and are prone to stress which damages their immune systems and makes them susceptible to disease citation needed In recent years however captive breeding has become more popular Such seahorses survive better in captivity and are less likely to carry diseases They eat frozen mysidacea crustaceans that are readily available from aquarium stores 50 and do not experience the stress of moving out of the wild Although captive bred seahorses are more expensive they take no toll on wild populations Seahorses should be kept in an aquarium with low flow and placid tank mates They are slow feeders so fast aggressive feeders will leave them without food 50 Seahorses can coexist with many species of shrimp and other bottom feeding creatures Gobies also make good tank mates Keepers are generally advised to avoid eels tangs triggerfish squid octopus and sea anemones 51 Water quality is very important for the survival of seahorses in an aquarium They are delicate species which should not be added to a new tank The water parameters are recommended to be as follows although these fish may acclimatise to different water over time Temperature 23 28 C 73 82 F pH 8 1 8 4 Ammonia 0 mg L 0 ppm 0 01 mg L 0 01 ppm may be tolerated for short periods Nitrite 0 mg L 0 ppm 0 125 mg L 0 125 ppm may be tolerated for short periods S G 1 021 1 024 at 23 24 C 73 75 F citation needed A water quality problem will affect fish behaviour and can be shown by clamped fins reduced feeding erratic swimming and gasping at the surface 52 Seahorses swim up and down as well as using the length of the aquarium Therefore the tanks should ideally be twice as deep as the length of the adult seahorse citation needed Animals sold as freshwater seahorses are usually the closely related pipefish of which a few species live in the lower reaches of rivers The supposed true freshwater seahorse called H aimei is not a valid species but a synonym sometimes used for Barbour s and hedgehog seahorses The latter which is often confused with the former can be found in estuarine environments but is not actually a freshwater fish 53 Use in Chinese medicine Edit Dried seahorse Seahorse and scorpion skewers as street foodSeahorse populations are thought to be endangered as a result of overfishing and habitat destruction Despite a lack of scientific studies or clinical trials 54 55 the consumption of seahorses is widespread in traditional Chinese medicine primarily in connection with impotence wheezing nocturnal enuresis and pain as well as labor induction 56 Up to 20 million seahorses may be caught each year to be sold for such uses 57 Preferred species of seahorses include H kellogii H histrix H kuda H trimaculatus and H mohnikei 56 Seahorses are also consumed by Indonesians central Filipinos and many other ethnic groups citation needed Import and export of seahorses has been controlled under CITES since 15 May 2004 However Indonesia Japan Norway and South Korea have chosen to opt out of the trade rules set by CITES The problem may be exacerbated by the growth of pills and capsules as the preferred method of ingesting seahorses Pills are cheaper and more available than traditional individually tailored prescriptions of whole seahorses but the contents are harder to track Seahorses once had to be of a certain size and quality before they were accepted by TCM practitioners and consumers Declining availability of the preferred large pale and smooth seahorses has been offset by the shift towards prepackaged preparations which makes it possible for TCM merchants to sell previously unused or otherwise undesirable juvenile spiny and dark coloured animals Today almost a third of the seahorses sold in China are packaged adding to the pressure on the species 58 Dried seahorse retails from US 600 to 3000 per kilogram with larger paler and smoother animals commanding the highest prices In terms of value based on weight seahorses retail for more than the price of silver and almost that of gold in Asia 59 Species EditBased on the newest overall taxonomic review 60 of the genus Hippocampus with further new species and partial taxonomic review 61 62 63 64 the number of recognized species in this genus is considered to be 46 retrieved May 2020 H kuda known as the common seahorse H subelongatus known as the West Australian seahorse H whitei known as White s seahorse Hippocampus abdominalis Lesson 1827 big belly seahorse Hippocampus algiricus Kaup 1856 West African seahorse Hippocampus angustus Gunther 1870 narrow bellied seahorse Hippocampus barbouri Jordan amp Richardson 1908 Barbour s seahorse Hippocampus bargibanti Whitley 1970 pygmy seahorse Hippocampus breviceps Peters 1869 short headed seahorse Hippocampus camelopardalis Bianconi 1854 giraffe seahorse Hippocampus capensis Boulenger 1900 Knysna seahorse Hippocampus casscsio Zhang Qin Wang amp Lin 2016 62 Beibu Bay seahorse Hippocampus colemani Kuiter 2003 Coleman s pygmy seahorse Hippocampus comes Cantor 1850 tiger tail seahorse Hippocampus coronatus Temminck amp Schlegel 1850 crowned seahorse Hippocampus curvicuspis Fricke 2004 New Caledonian seahorse Hippocampus dahli J D Ogilby 1908 lowcrown seahorse Hippocampus debelius Gomon amp Kuiter 2009 softcoral seahorse Hippocampus denise Lourie amp Randall 2003 Denise s pygmy seahorse Hippocampus erectus Perry 1810 lined seahorse Hippocampus fisheri Jordan amp Evermann 1903 Fisher s seahorse Hippocampus guttulatus Cuvier 1829 long snouted seahorse Hippocampus haema Han Kim Kai amp Senou 2017 63 Korean seahorse Hippocampus hippocampus Linnaeus 1758 short snouted seahorse Hippocampus histrix Kaup 1856 spiny seahorse Hippocampus ingens Girard 1858 Pacific seahorse Hippocampus japapigu Short R Smith Motomura Harasti amp H Hamilton 2018 61 Japanese pygmy seahorse Hippocampus jayakari Boulenger 1900 Jayakar s seahorse Hippocampus jugumus Kuiter 2001 collared seahorse Hippocampus kelloggi Jordan amp Snyder 1901 great seahorse Hippocampus kuda Bleeker 1852 spotted seahorse Hippocampus minotaur Gomon 1997 bullneck seahorse Hippocampus mohnikei Bleeker 1854 Japanese seahorse Hippocampus nalu Short Claassens R Smith De Brauwer H Hamilton Stat amp Harasti 2020 64 South African pygmy seahorse or Sodwana pygmy seahorse Hippocampus paradoxus Foster amp Gomon 2010 paradoxical seahorse Hippocampus patagonicus Piacentino amp Luzzatto 2004 Patagonian seahorse Hippocampus planifrons Peters 1877 flatface seahorse false eye seahorse Hippocampus pontohi Lourie amp Kuiter 2008 Pontoh s pygmy seahorse Hippocampus pusillus Fricke 2004 pygmy thorny seahorse Hippocampus reidi Ginsburg 1933 longsnout seahorse Hippocampus satomiae Lourie amp Kuiter 2008 Satomi s pygmy seahorse Hippocampus sindonis Jordan amp Snyder 1901 Sindo s seahorse Hippocampus spinosissimus Weber 1913 hedgehog seahorse Hippocampus subelongatus Castelnau 1873 West Australian seahorse Hippocampus trimaculatus Leach 1814 longnose seahorse Hippocampus tyro Randall amp Lourie 2009 Tyro seahorse Hippocampus waleananus Gomon amp Kuiter 2009 61 Walea soft coral pygmy seahorse Hippocampus whitei Bleeker 1855 White s seahorse Hippocampus zebra Whitley 1964 zebra seahorse Hippocampus zosterae Jordan amp Gilbert 1882 dwarf seahorse Pygmy seahorses EditMain article Hippocampinae Hippocampus satomiae Satomi s pygmy seahorse attached to coral Pygmy seahorses are those members of the genus that are less than 15 mm 9 16 in tall and 17 mm 11 16 in wide Previously the term was applied exclusively to the species H bargibanti but since 1997 discoveries have made this usage obsolete The species H minotaur H denise H colemani H pontohi H severnsi H satomiae H waleananus H nalu H japapigu have been described Other species that are believed to be unclassified have also been reported in books dive magazines and on the Internet They can be distinguished from other species of seahorse by their 12 trunk rings low number of tail rings 26 29 the location in which young are brooded in the trunk region of males and their extremely small size 65 Molecular analysis of ribosomal RNA of 32 Hippocampus species found that H bargibanti belongs in a separate clade from other members of the genus and therefore that the species diverged from the other species in the ancient past 66 Most pygmy seahorses are well camouflaged and live in close association with other organisms including colonial hydrozoans Lytocarpus and Antennellopsis coralline algae Halimeda sea fans Muricella Annella Acanthogorgia This combined with their small size accounts for why most species have only been noticed and classified since 2001 65 67 References Edit Rafinesque Schmaltz C S 1810 G Hippocampus Caratteri di alcuni nuovi generi e nuove specie di animali e piante della Sicilia con varie osservazioni sopra i medesimi Palermo Sanfilippo p 18 Hippocampus Rafinesque 1810 WoRMS Whitley Gilbert P 1931 New Names for Australian Fishes The Australian Zoologist 6 4 313 Shorter Oxford English Dictionary Oxford UK Oxford University Press 2007 ISBN 978 0199206872 ἱppokampos ἵppos kampos Liddell Henry George Scott Robert A Greek English Lexicon at the Perseus Project Jarvis Dr Peter 13 January 2020 The Pelagic Dictionary of Natural History of the British Isles Descriptions of all Species with a Common Name Pelagic Publishing Ltd ISBN 978 1 78427 196 1 sea horse or seahorse dictionary com Retrieved 19 June 2016 Home Project Seahorse Retrieved 15 November 2015 Rare seahorses breeding in Thames BBC News 7 April 2008 Retrieved 11 November 2009 Seahorses Seahorse Pictures Seahorse Facts National Geographic Retrieved 17 May 2012 Observatoire Oceanologique de Banyuls sur mer www obs banyuls fr Retrieved 16 November 2015 Porter Michael M Novitskaya Ekaterina Castro Cesena Ana Bertha Meyers Marc A McKittrick Joanna 2013 Highly deformable bones Unusual deformation mechanisms of seahorse armor Acta Biomaterialia 9 6 6763 6770 doi 10 1016 j actbio 2013 02 045 PMID 23470547 The galloping evolution in seahorses Entire genome of the seahorse sequenced ScienceDaily Porter Michael M Adriaens Dominique Hatton Ross L Meyers Marc A McKittrick Joanna 2015 Why the seahorse tail is square Science 349 6243 aaa6683 doi 10 1126 science aaa6683 PMID 26138983 Garrick Maidment N Trewhella S Hatcher J Collins K j Mallinson J j 1 January 2010 Seahorse Tagging Project Studland Bay Dorset UK Marine Biodiversity Records 3 doi 10 1017 S175526721000062X ISSN 1755 2672 Freret Meurer Natalie 2013 Seahorse Fingerprints A New Individual Identification Technique Environmental Biology of Fishes 96 12 1399 1405 doi 10 1007 s10641 013 0118 6 S2CID 13917616 Guinness Book of World Records 2009 Lourie Sara 2016 Seahorses A Life size Guide to Every Species Ivy Press ISBN 9781782403210 Zalohar J Hitij T Kriznar M 2009 Two new species of seahorses Syngnathidae Hippocampus from the Middle Miocene Sarmatian Coprolitic Horizon in Tunjice Hills Slovenia The oldest fossil record of seahorses Annales de Paleontologie 95 2 71 96 doi 10 1016 j annpal 2009 03 002 Teske PR Beheregaray LB 2009 Evolution of seahorses upright posture was linked to Oligocene expansion of seagrass habitats Biol Lett 5 4 521 3 doi 10 1098 rsbl 2009 0152 PMC 2781918 PMID 19451164 Teske PR Cherry MI Matthee CA 2004 The evolutionary history of seahorses Syngnathidae Hippocampus molecular data suggest a West Pacific origin and two invasions of the Atlantic Ocean Mol Phylogenet Evol 30 2 273 86 doi 10 1016 S1055 7903 03 00214 8 PMID 14715220 a b Lin Qiang Fan Shaohua Zhang Yanhong Xu Meng Zhang Huixian Yang Yulan et al 14 December 2016 The seahorse genome and the evolution of its specialized morphology Nature 540 7633 395 399 Bibcode 2016Natur 540 395L doi 10 1038 nature20595 PMC 8127814 PMID 27974754 Van Wassenbergh Sam Roos Gert Ferry Lara 25 January 2011 An adaptive explanation for the horse like shape of seahorses Nature Communications 2 1 164 Bibcode 2011NatCo 2 164V doi 10 1038 ncomms1168 ISSN 2041 1723 PMID 21266964 Foster S J Vincent C J 2004 Life history and ecology of seahorses implications for conservation and management Journal of Fish Biology 65 1 61 doi 10 1111 j 0022 1112 2004 00429 x a b c Milius S 2000 Pregnant And Still Macho PDF Science News 157 11 168 170 doi 10 2307 4012130 JSTOR 4012130 Archived PDF from the original on 18 August 2011 Robinson James L 2013 Seahorses full citation needed a b c d e Masonjones Heather D Lewis Sara M 1996 Courtship Behavior in the Dwarf Seahorse Hippocampus zosterae Copeia 1996 3 634 640 doi 10 2307 1447527 JSTOR 1447527 Look Katrien J W Van Dzyuba Borys Cliffe Alex Koldewey Heather J Holt William V 1 February 2007 Dimorphic sperm and the unlikely route to fertilisation in the yellow seahorse Journal of Experimental Biology 210 3 432 437 doi 10 1242 jeb 02673 ISSN 0022 0949 PMID 17234612 Kvarnemo Charlotta Simmons Leigh W 2004 Testes investment and spawning mode in pipefishes and seahorses Syngnathidae Biological Journal of the Linnean Society 83 3 369 376 doi 10 1111 j 1095 8312 2004 00395 x a b The biology of seahorses Reproduction The Seahorse Project Archived from the original on 3 March 2009 Retrieved 8 May 2007 Dudley Jessica October 2021 Structural changes to the brood pouch of male pregnant seahorses Hippocampus abdominalis facilitate exchange between father and embryos Placenta 114 115 123 doi 10 1016 j placenta 2021 09 002 PMID 34517263 S2CID 237505281 Whittington Camilla M Griffith Oliver W Qi Weihong Thompson Michael B Wilson Anthony B 1 September 2015 Seahorse Brood Pouch Transcriptome Reveals Common Genes Associated with Vertebrate Pregnancy Molecular Biology and Evolution 32 12 3114 31 doi 10 1093 molbev msv177 ISSN 0737 4038 PMID 26330546 Masonjones H D Lewis S M 2000 Differences in potential reproductive rates of male and female seahorses related to courtship roles Animal Behaviour 59 1 11 20 doi 10 1006 anbe 1999 1269 PMID 10640362 S2CID 5999610 a b Danielson Stentor 14 June 2002 Seahorse Fathers Take Reins in Childbirth National Geographic News Vincent Amanda C J 1994 Operational Sex Ratios in Seahorses Behaviour 128 1 2 153 167 doi 10 1163 156853994X00091 JSTOR 4535169 Why Do Male Seahorses Get Pregnant Petseahorse com Kvarnemo C Moore G I Jones A G Nelson W S Avise J C 2000 Monogamous pair bonds and mate switching in the Western Australian seahorse Hippocampus subelongatus J Evol Biol 13 6 882 8 doi 10 1046 j 1420 9101 2000 00228 x S2CID 40777563 Vincent C J Sadler L M 1995 Faithful pair bonds in wild seahorses Hippocampus whitei PDF Anim Behav 50 6 1557 1569 doi 10 1016 0003 3472 95 80011 5 S2CID 53192875 Archived from the original PDF on 23 July 2011 Weiss Tami 10 April 2010 What s Love Got to Do With It The Truth About Seahorse Monogamy fusedjaw com Alcock John 2005 Animal Behavior 8th ed Massachusetts Sinauer pp 370 1 ISBN 978 0878930050 a b Langley Liz 26 November 2013 Why Does the Seahorse Have Its Odd Head Mystery Solved News Watch Newswatch nationalgeographic com a b Woods Chris M C September 2002 Natural diet of the seahorse Hippocampus abdominalis New Zealand Journal of Marine and Freshwater Research 36 3 655 660 doi 10 1080 00288330 2002 9517121 ISSN 0028 8330 Flynn A J Ritz D A June 1999 Effect of habitat complexity and predatory style on the capture success of fish feeding on aggregated prey Journal of the Marine Biological Association of the United Kingdom 79 3 487 494 doi 10 1017 s0025315498000617 ISSN 1469 7769 S2CID 86160386 a b Gemmell B J Sheng J Buskey E J 2013 Morphology of seahorse head hydrodynamically aids in capture of evasive prey Nature Communications 4 2840 Bibcode 2013NatCo 4 2840G doi 10 1038 ncomms3840 PMID 24281430 Wassenbergh Sam Van Strother James A Flammang Brooke E Ferry Graham Lara A Aerts Peter 6 March 2008 Extremely fast prey capture in pipefish is powered by elastic recoil Journal of the Royal Society Interface 5 20 285 296 doi 10 1098 rsif 2007 1124 ISSN 1742 5689 PMC 2607401 PMID 17626004 Bergert B A Wainwright P C 14 March 1997 Morphology and kinematics of prey capture in the syngnathid fishes Hippocampus erectus and Syngnathus floridae Marine Biology 127 4 563 570 doi 10 1007 s002270050046 ISSN 0025 3162 S2CID 84452341 Rosa Ierece L Dias Thelma L Baum Julia K 2002 Threatened Fishes of the World Hippocampus reidi Ginsburg 1933 Syngnathidae Environmental Biology of Fishes 64 4 378 doi 10 1023 a 1016152528847 ISSN 0378 1909 S2CID 26782777 Lourie Sarah A Foster Sarah J Cooper Ernest W T and Vincent Amanda C J 2004 A Guide to the Identification of Seahorses Project Seahorse Advancing Marine Conservation ISBN 0 89164 169 6 Lawson J M Foster S J Vincent A C J January 2017 Low bycatch rates add up to big numbers for a genus of small fishes Fisheries Magazine American Fisheries Society 42 1 19 33 doi 10 1080 03632415 2017 1259944 a b Seahorse and Pipefish Foods Tami Weiss Fusedjaw com 25 June 2005 Retrieved 11 November 2009 Seahorse Tankmates Will Wooten Fusedjaw com 25 June 2004 Retrieved 11 November 2009 How to care for Seahorses amp Pipefish seahorseaquariums ie Hippocampus spinosissimus Fishbase Retrieved 11 November 2009 Stephen Barrett M D 12 January 2011 Be Wary of Acupuncture Qigong and Chinese Medicine Retrieved 11 December 2013 Still J 2003 Use of animal products in traditional Chinese medicine Environmental impact and health hazards Complementary Therapies in Medicine 11 2 118 22 doi 10 1016 S0965 2299 03 00055 4 PMID 12801499 a b Bensky D Clavey S Stoger E 2004 Chinese Herbal Medicine Materia Medica Eastland Press Inc Seattle 3rd ed ISBN 0939616424 p 815 Seahorse Crusader Amanda Vincent on Nova television show Parry Jones Rob amp Vincent Amanda 3 January 1998 Can we tame wild medicine New Scientist Save Our Seahorses Save Our Seahorses Retrieved 13 May 2014 LOURIE SARA A POLLOM RILEY A FOSTER SARAH J 1 August 2016 A global revision of the Seahorses Hippocampus Rafinesque 1810 Actinopterygii Syngnathiformes Taxonomy and biogeography with recommendations for further research Zootaxa 4146 1 1 66 doi 10 11646 zootaxa 4146 1 1 ISSN 1175 5334 PMID 27515600 a b c Short Graham Smith Richard Motomura Hiroyuki Harasti David Hamilton Healy 2 August 2018 Hippocampus japapigu a new species of pygmy seahorse from Japan with a redescription of H pontohi Teleostei Syngnathidae ZooKeys 779 27 49 doi 10 3897 zookeys 779 24799 ISSN 1313 2970 PMC 6110155 PMID 30166895 a b Zhang Yan Hong Qin Geng Wang Xin Lin Qiang 23 September 2016 A new species of seahorse Teleostei Syngnathidae from the South China Sea Zootaxa 4170 2 384 392 doi 10 11646 zootaxa 4170 2 11 ISSN 1175 5334 PMID 27701270 a b Han Sang Yun Kim Jin Koo Kai Yoshiaki Senou Hiroshi 30 October 2017 Seahorses of the Hippocampus coronatus complex taxonomic revision and description of Hippocampus haema a new species from Korea and Japan Teleostei Syngnathidae ZooKeys 712 113 139 doi 10 3897 zookeys 712 14955 ISSN 1313 2970 PMC 5704180 PMID 29187790 a b Short Graham Claassens Louw Smith Richard De Brauwer Maarten Hamilton Healy Stat Michael Harasti David 19 May 2020 Hippocampus nalu a new species of pygmy seahorse from South Africa and the first record of a pygmy seahorse from the Indian Ocean Teleostei Syngnathidae ZooKeys 934 141 156 doi 10 3897 zookeys 934 50924 PMC 7253503 PMID 32508498 a b Lourie Sara Rudie Kuiter 2008 Three new pygmy seahorse species from Indonesia Teleostei Syngnathidae Hippocampus PDF Zootaxa 1963 54 68 doi 10 11646 zootaxa 1963 1 4 ISSN 1175 5334 Archived PDF from the original on 4 December 2010 Retrieved 9 June 2009 Teske Peter Michael Cherry Conrad Matthee February 2004 The evolutionary history of seahorses Syngnathidae Hippocampus molecular data suggest a West Pacific origin and two invasions of the Atlantic Ocean Molecular Phylogenetics and Evolution 30 2 273 286 doi 10 1016 S1055 7903 03 00214 8 PMID 14715220 Science in Pictures Pygmy Seahorses The Epoch Times Northern California Edition 8 November 2011 Further reading EditAmanda C J Vincent amp Laila M Sadler 1995 Faithful pair bonds in wild seahorse Hippocampus whitei Animal Behaviour 50 6 1557 69 doi 10 1016 0003 3472 95 80011 5 S2CID 53192875 Amanda C J Vincent 1995 A role for daily greetings in maintaining seahorse pair bonds Animal Behaviour 49 258 260 doi 10 1016 0003 3472 95 80178 2 S2CID 54391512 Amanda C J Vincent 1990 A seahorse father makes a good mother Natural History 12 34 43 Amanda C J Vincent amp Rosie Woodroffe 1994 Mothers little helpers patterns of male care in mammals Trends in Ecology and Evolution 9 8 294 7 doi 10 1016 0169 5347 94 90033 7 PMID 21236858 John Sparks 1999 Battle of the Sexes The Natural History of Sex London BBC Books ISBN 978 0 563 37145 8 Sara A Lourie Amanda C J Vincent and Heather J Hall 1999 Seahorses An Identification Guide to the World s Species and their Conversation London Project Seahorse Teske Peter R Hamilton Healy Matthee Conrad A Barker Nigel P 15 August 2007 Signatures of seaway closures and founder dispersal in the phylogeny of a circumglobally distributed seahorse lineage BMC Evolutionary Biology 7 138 doi 10 1186 1471 2148 7 138 ISSN 1471 2148 PMC 1978501 PMID 17697373 External links Edit Wikimedia Commons has media related to Seahorse Wikisource has the text of the 1911 Encyclopaedia Britannica article Sea horse Retrieved from https en wikipedia org w index php title Seahorse amp oldid 1132353894, wikipedia, wiki, book, books, library,

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