Telson
The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the uropods, the telson forms the tail fan of lobsters, shrimp and other decapods. These are 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 ms.
The same term telson is widely used for the caudal spine of Chelicerata.[1][2] 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, like Karl-Ernst Lauterbach, have urged that the usage of this word in this context be discouraged.[3]
[edit] See also
[edit] References
- ^ Richard C. Brusca & Gary J. Brusca (2003). Invertebrates (2nd ed.). Sinauer Associates. pp. 1–936. ISBN 0-87893-097-3.
- ^ E. E. Ruppert & R. D. Barnes (1994). Invertebrate Zoology (6th ed.). Saunders. ISBN 0030266688.
- ^ 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)]" (in German). Abhandlungen des Naturwissenschaftlichen Vereins in Hamburg. NF 23: 163–327.
