The telson (from Ancient Greek τέλσον 'headlands, limit') is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on account of not arising in the embryo from teloblast areas as other segments.[1] It never carries any appendages, but a forked "tail" called the caudal furca may be present. The shape and composition of the telson differs between arthropod groups.
In lobsters, shrimp and other decapods, the telson, along with the uropods, forms the tail fan. This is used as a paddle in the caridoid escape reaction ("lobstering"), whereby an alarmed animal rapidly flexes its tail, causing it to dart backwards. Krill can reach speeds of over 60 cm per second by this means. The trigger time to optical stimulus is, in spite of the low temperatures, only 55 milliseconds.
In the Isopoda and Tanaidacea (superorder Peracarida), the last abdominal body segment is fused with the telson, forming a "pleotelson".[2]
The term telson is widely used for the caudal spine of some chelicerates.[3][4] The chelicerate telson can be clearly seen in a number of fossil species (like in eurypterids) and in extant animals (like the horseshoe crab "tail" and the scorpion sting). Some authorities have urged that the usage of this word in this context be discouraged.[why?][5]
Myriapods
Telson of a millipede, including an epiproct (e), hypoproct (h) and paraprocts (p)
In millipedes, the telson consists of a legless pre-anal body segment (which may contain a posterior extension known as an epiproct), a pair of anal valves (paraprocts) or plates closing off the anus, and a plate below the anus (hypoproct), also known as a subanal scale.[6][7]
In centipedes the telson is the rear-most body segment, posterior to the genital openings, bearing two anal valves.[8]
Hexapods
Proturans, an order of minute soil-dwelling animals, are the only hexapods with a telson.[9]
^Karl-Ernst Lauterbach (1980). "Schlüsselereignisse in der Evolution des Grundplans der Arachnata (Arthropoda)" [Key events in the evolution of the ground plan of the Arachnata (Arthropoda)]. Abhandlungen des Naturwissenschaftlichen Vereins in Hamburg. NF (in German). 23: 163–327.
^Sierwald, Petra; Bond, Jason E. (2007). "Current Status of the Myriapod Class Diplopoda (Millipedes): Taxonomic Diversity and Phylogeny". Annual Review of Entomology. 52 (1): 401–420. doi:10.1146/annurev.ento.52.111805.090210. PMID 17163800.
^Mesibov, Robert. "Tail". External Anatomy of Polydesmida. Retrieved 4 November 2013.
^The Phylogenetic Positions of Three Basal-Hexapod Groups (Protura, Diplura, and Collembola) Based on Ribosomal RNA Gene Sequences
May 20, 2023
telson, copepod, genus, copepod, telson, from, ancient, greek, τέλσον, headlands, limit, posterior, most, division, body, arthropod, depending, definition, telson, either, considered, final, segment, arthropod, body, additional, division, that, true, segment, . For the copepod genus see Telson copepod The telson from Ancient Greek telson headlands limit is the posterior most division of the body of an arthropod Depending on the definition the telson is either considered to be the final segment of the arthropod body or an additional division that is not a true segment on account of not arising in the embryo from teloblast areas as other segments 1 It never carries any appendages but a forked tail called the caudal furca may be present The shape and composition of the telson differs between arthropod groups Diagram highlighting the telson of the prawn Litopenaeus setiferusTelson arrow no 3 of the horseshoe crab Carcinoscorpius rotundicauda Contents 1 Crustaceans 2 Chelicerates 3 Myriapods 4 Hexapods 5 See also 6 ReferencesCrustaceans EditIn lobsters shrimp and other decapods the telson along with the uropods forms the tail fan This is used as a paddle in the caridoid escape reaction lobstering whereby an alarmed animal rapidly flexes its tail causing it to dart backwards Krill can reach speeds of over 60 cm per second by this means The trigger time to optical stimulus is in spite of the low temperatures only 55 milliseconds In the Isopoda and Tanaidacea superorder Peracarida the last abdominal body segment is fused with the telson forming a pleotelson 2 Chelicerates Edit Hottentotta tamulus scorpion showing telson The term telson is widely used for the caudal spine of some chelicerates 3 4 The chelicerate telson can be clearly seen in a number of fossil species like in eurypterids and in extant animals like the horseshoe crab tail and the scorpion sting Some authorities have urged that the usage of this word in this context be discouraged why 5 Myriapods Edit Telson of a millipede including an epiproct e hypoproct h and paraprocts p In millipedes the telson consists of a legless pre anal body segment which may contain a posterior extension known as an epiproct a pair of anal valves paraprocts or plates closing off the anus and a plate below the anus hypoproct also known as a subanal scale 6 7 In centipedes the telson is the rear most body segment posterior to the genital openings bearing two anal valves 8 Hexapods EditProturans an order of minute soil dwelling animals are the only hexapods with a telson 9 See also EditOpisthosoma PygidiumReferences Edit Crustacea Glossary Definitions research nhm org Retrieved 2021 08 03 S J Keable G C B Poore amp G D F Wilson October 2 2002 Australian Isopoda Families Australian Museum Richard C Brusca amp Gary J Brusca 2003 Invertebrates 2nd ed Sinauer Associates pp 1 936 ISBN 0 87893 097 3 E E Ruppert amp R D Barnes 1994 Invertebrate Zoology 6th ed Saunders ISBN 0 03 026668 8 Karl Ernst Lauterbach 1980 Schlusselereignisse in der Evolution des Grundplans der Arachnata Arthropoda Key events in the evolution of the ground plan of the Arachnata Arthropoda Abhandlungen des Naturwissenschaftlichen Vereins in Hamburg NF in German 23 163 327 Sierwald Petra Bond Jason E 2007 Current Status of the Myriapod Class Diplopoda Millipedes Taxonomic Diversity and Phylogeny Annual Review of Entomology 52 1 401 420 doi 10 1146 annurev ento 52 111805 090210 PMID 17163800 Mesibov Robert Tail External Anatomy of Polydesmida Retrieved 4 November 2013 Lewis J G E 2008 The Biology of Centipedes Digitally printed 1st paperback version ed Cambridge Cambridge University Press ISBN 9780521034111 The Phylogenetic Positions of Three Basal Hexapod Groups Protura Diplura and Collembola Based on Ribosomal RNA Gene Sequences Retrieved from https en wikipedia org w index php title Telson amp oldid 1121791184, wikipedia, wiki, book, books, library,
