Mordacia mordax, known as the short-headed lamprey, Australian lamprey or Murray lamprey, is a species of Mordacia that lives in south-eastern Australia and Tasmania. Mordaciidae is made up of three species: M. praedox, M. mordax, and M. lapicida.[1]M. mordax is a relatively rare, parasitic vertebrate and, along with the hagfishes, is part of the only surviving group of jawless organisms throughout vertebrate evolution.[2] It has a thin eel-like body up to 50 cm (20 in) long, with two low dorsal fins on the back half. The skin is blue-gray or brown. Its eyes are small, and located on the top of its head.
Members of Agnatha have been found in the fossil record for approximately five hundred million years and it has been identified as an important group in tracking vertebrate evolution.[1] Despite being spatially close to the other southern hemisphere family Geotriidae, M. mordax has been shown to have key proteins with vastly different amino acid compositions.[3][2] One such study of insulin extracted from organisms of both species indicated that 18 amino acids are different between G. australis and M. mordax when with northern hemisphere lampreys (P. marinus and L. fluviatilis) there is only a four amino acid difference. This data indicates that the southern hemisphere lampreys likely diverged evolutionarily a long time before.[2] It has also been determined that Geotriidae and Petromyzontidae (the family of northern lampreys) likely share a more recent common ancestor than either does with any Mordacia species.[3]
Behavior and ecologyEdit
Adult M. mordax are parasites on other fish. They are anadromous (breeding in fresh water), migrating up streams in southeastern Australia from Shoalhaven River, New South Wales to Gulf St Vincent, South Australia. The ammocoetes (lamprey larvae) remain in fresh water until undergoing extreme physiological changes that allow them to move from eating plankton to larger fish.[1] This leads to them migrating to the South Pacific and Southern Oceans around three to four years after hatching.[2] Adults have been found to travel hundreds of miles to spawn.[4] Feeding occurs in the open ocean until full sexual maturation occurs when M. mordax returns to freshwater rivers, spawns, and dies.[5]
PhysiologyEdit
Larval M. mordax are between 20 and 150 mm (0.79 and 5.91 in) in length depending on their stage of development and when fully developed typically measure 300 to 420 mm (12 to 17 in).[5] As it develops, M. mordax undergoes a number of extreme dental changes. It starts with a series of radial plates, and as it grows they separate and break into separate teeth.[4] These teeth are pointed, unlike the other southern hemisphere lamprey Geotria australis which has spatulate (broad and rounded) teeth.[4]
The eyes of Mordacia are dorsolaterally located, which is unlike the other known lamprey species, and they contain a photoreceptor that has both rod and cone characteristics.[1] This photoreceptor is also unique to M. mordax and enhances vision in darkness by optimizing photon reception. It is not unlike deep sea fish eye anatomy, in that sense as M. mordax only comes out of the sediment of rivers at night to travel.[5]
The posterior and anterior dorsal fins of Mordacia are continuous to the caudal fin, unlike G. australis. When M. mordax is fully developed those anterior and posterior dorsal fins are well separated, which distinguishes them from northern hemisphere lampreys.[4]
Lampreys have been established as worthy models in understanding the development of higher vertebrate anatomy and physiology, with one such experiment determining that major classes of lipoproteins are similar in Mordacia to those found in humans.[6]M. mordax and the lamprey group have also been shown to be the lowest vertebrate to have clear roles for neurohormones in the hypothalamic-pituitary-gonadal axis.[7]
ReferencesEdit
^ abcdCollin, S; Hart, N; Wallace, K; Shand, J; Potter, I (2004). "Vision in the southern hemisphere lamprey Mordacia mordax: Spatial distribution, spectral absorption characteristics, and optical sensitivity of a single class of retinal photoreceptor" (PDF). Visual Neuroscience. 21 (5): 765–773. doi:10.1017/S0952523804215103. PMID 15683562. S2CID 11947584.
^ abcdConlon; Wang; Potter (2001). "The structure of Mordacia mordax insulin supports the monophyly of the Petromyzontiformes and an ancient divergence of Mordaciidae and Geotriidae". Comparative Biochemistry and Physiology, Part B. 129 (1): 65–71. doi:10.1016/S1096-4959(00)00365-1. PMID 11337250.
^ abBaldwin, Mortimer (1988). "Evolutionary relationships among lamprey families: Amino acid composition analysis of lactate dehydrogenase". Biochemical Systematics and Ecology. 16 (3): 351–353. doi:10.1016/0305-1978(88)90022-1.
^ abcdPotter, I; Strahan, F (1968). "The taxonomy of the lampreys Geotria and Mordacia and their distribution in Australia". Proceedings of the Linnean Society of London. 179 (2): 229–240. doi:10.1111/j.1095-8312.1968.tb00980.x.
^ abcPotter, I; Hilliard, R; Neira, F (1986). "The Biology of Australian Lampreys". {{cite journal}}: Cite journal requires |journal= (help)
^Fellows, Florence; Mclean, Robyn (1982). "A study of the plasma lipoproteins and the tissue lipids of the migrating lamprey, Mordacia mordax". Lipids. 17 (10): 741–747. doi:10.1007/BF02534661. PMID 7176831. S2CID 4024259.
^Sower; Mcgregor; Materne; Chase; Potter; Joss (2000). "Evidence for Lamprey GnRH-I and -III-like Molecules in the Brains of the Southern Hemisphere Lampreys Geotria australis and Mordacia mordax". General and Comparative Endocrinology. 120 (2): 168–75. doi:10.1006/gcen.2000.7550. PMID 11078628.
October 21, 2023
mordacia, mordax, known, short, headed, lamprey, australian, lamprey, murray, lamprey, species, mordacia, that, lives, south, eastern, australia, tasmania, mordaciidae, made, three, species, praedox, mordax, lapicida, mordax, relatively, rare, parasitic, verte. Mordacia mordax known as the short headed lamprey Australian lamprey or Murray lamprey is a species of Mordacia that lives in south eastern Australia and Tasmania Mordaciidae is made up of three species M praedox M mordax and M lapicida 1 M mordax is a relatively rare parasitic vertebrate and along with the hagfishes is part of the only surviving group of jawless organisms throughout vertebrate evolution 2 It has a thin eel like body up to 50 cm 20 in long with two low dorsal fins on the back half The skin is blue gray or brown Its eyes are small and located on the top of its head Short headed lampreyScientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataInfraphylum AgnathaClass HyperoartiaOrder PetromyzontiformesFamily MordaciidaeGenus MordaciaSpecies M mordaxBinomial nameMordacia mordax J Richardson 1846 SynonymsPetromyzon mordax J Richardson 1846 Contents 1 Evolution 2 Behavior and ecology 3 Physiology 4 ReferencesEvolution EditMembers of Agnatha have been found in the fossil record for approximately five hundred million years and it has been identified as an important group in tracking vertebrate evolution 1 Despite being spatially close to the other southern hemisphere family Geotriidae M mordax has been shown to have key proteins with vastly different amino acid compositions 3 2 One such study of insulin extracted from organisms of both species indicated that 18 amino acids are different between G australis and M mordax when with northern hemisphere lampreys P marinus and L fluviatilis there is only a four amino acid difference This data indicates that the southern hemisphere lampreys likely diverged evolutionarily a long time before 2 It has also been determined that Geotriidae and Petromyzontidae the family of northern lampreys likely share a more recent common ancestor than either does with any Mordacia species 3 Behavior and ecology EditAdult M mordax are parasites on other fish They are anadromous breeding in fresh water migrating up streams in southeastern Australia from Shoalhaven River New South Wales to Gulf St Vincent South Australia The ammocoetes lamprey larvae remain in fresh water until undergoing extreme physiological changes that allow them to move from eating plankton to larger fish 1 This leads to them migrating to the South Pacific and Southern Oceans around three to four years after hatching 2 Adults have been found to travel hundreds of miles to spawn 4 Feeding occurs in the open ocean until full sexual maturation occurs when M mordax returns to freshwater rivers spawns and dies 5 Physiology EditLarval M mordax are between 20 and 150 mm 0 79 and 5 91 in in length depending on their stage of development and when fully developed typically measure 300 to 420 mm 12 to 17 in 5 As it develops M mordax undergoes a number of extreme dental changes It starts with a series of radial plates and as it grows they separate and break into separate teeth 4 These teeth are pointed unlike the other southern hemisphere lamprey Geotria australis which has spatulate broad and rounded teeth 4 The eyes of Mordacia are dorsolaterally located which is unlike the other known lamprey species and they contain a photoreceptor that has both rod and cone characteristics 1 This photoreceptor is also unique to M mordax and enhances vision in darkness by optimizing photon reception It is not unlike deep sea fish eye anatomy in that sense as M mordax only comes out of the sediment of rivers at night to travel 5 The posterior and anterior dorsal fins of Mordacia are continuous to the caudal fin unlike G australis When M mordax is fully developed those anterior and posterior dorsal fins are well separated which distinguishes them from northern hemisphere lampreys 4 Lampreys have been established as worthy models in understanding the development of higher vertebrate anatomy and physiology with one such experiment determining that major classes of lipoproteins are similar in Mordacia to those found in humans 6 M mordax and the lamprey group have also been shown to be the lowest vertebrate to have clear roles for neurohormones in the hypothalamic pituitary gonadal axis 7 References Edit a b c d Collin S Hart N Wallace K Shand J Potter I 2004 Vision in the southern hemisphere lamprey Mordacia mordax Spatial distribution spectral absorption characteristics and optical sensitivity of a single class of retinal photoreceptor PDF Visual Neuroscience 21 5 765 773 doi 10 1017 S0952523804215103 PMID 15683562 S2CID 11947584 a b c d Conlon Wang Potter 2001 The structure of Mordacia mordax insulin supports the monophyly of the Petromyzontiformes and an ancient divergence of Mordaciidae and Geotriidae Comparative Biochemistry and Physiology Part B 129 1 65 71 doi 10 1016 S1096 4959 00 00365 1 PMID 11337250 a b Baldwin Mortimer 1988 Evolutionary relationships among lamprey families Amino acid composition analysis of lactate dehydrogenase Biochemical Systematics and Ecology 16 3 351 353 doi 10 1016 0305 1978 88 90022 1 a b c d Potter I Strahan F 1968 The taxonomy of the lampreys Geotria and Mordacia and their distribution in Australia Proceedings of the Linnean Society of London 179 2 229 240 doi 10 1111 j 1095 8312 1968 tb00980 x a b c Potter I Hilliard R Neira F 1986 The Biology of Australian Lampreys a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Fellows Florence Mclean Robyn 1982 A study of the plasma lipoproteins and the tissue lipids of the migrating lamprey Mordacia mordax Lipids 17 10 741 747 doi 10 1007 BF02534661 PMID 7176831 S2CID 4024259 Sower Mcgregor Materne Chase Potter Joss 2000 Evidence for Lamprey GnRH I and III like Molecules in the Brains of the Southern Hemisphere Lampreys Geotria australis and Mordacia mordax General and Comparative Endocrinology 120 2 168 75 doi 10 1006 gcen 2000 7550 PMID 11078628 Retrieved from https en wikipedia org w index php title Mordacia mordax amp oldid 1102368413, 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