Telson
Carcinoscorpius rotundicauda
The telson (from
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.
Crustaceans
In
milliseconds
.
In the Isopoda and Tanaidacea (superorder Peracarida), the last abdominal body segment is fused with the telson, forming a "pleotelson".[2]
Chelicerates
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
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 hindmost 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]
See also
References
- ^ "Crustacea Glossary::Definitions". research.nhm.org. Retrieved 2021-08-03.
- ^ S. J. Keable, G. C. B. Poore & G. D. F. Wilson (October 2, 2002). "Australian Isopoda: Families". Australian Museum.
- ISBN 0-87893-097-3.
- ISBN 0-03-026668-8.
- ^ 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.
- PMID 17163800.
- ^ Mesibov, Robert. "Tail". External Anatomy of Polydesmida. Retrieved 4 November 2013.
- ISBN 9780521034111.
- ^ The Phylogenetic Positions of Three Basal-Hexapod Groups (Protura, Diplura, and Collembola) Based on Ribosomal RNA Gene Sequences