Knowra Telson Telson The terminal body structure extending beyond the abdomen in some arthropods, including horseshoe crabs. It is distinct from the segmented abdomen and may aid movement, defense, or righting.
Arthropod : An invertebrate animal with a segmented body, jointed appendages, and a chitinous exoskeleton. The telson occurs in several arthropod groups, but is not a universal feature.
Horseshoe crab : A marine chelicerate arthropod with a broad horseshoe-shaped carapace and a long, pointed telson. Its conspicuous telson helps the animal right itself when overturned.
Tail fan : A fan-shaped structure at the rear of some crustaceans, formed by the telson and paired uropods. The telson forms the central part of this swimming and steering surface.
Pygidium : A posterior body region formed from fused segments in some annelids and arthropods. A pygidium is a segmented terminal region, whereas the telson is usually not a true segment.
Abdomen : The posterior body region of an animal, often containing digestive, reproductive, or respiratory organs. The telson lies behind the abdomen rather than forming one of its segments.
Limulus polyphemus : The Atlantic horseshoe crab species found along the eastern coasts of North America. This species is a familiar example of a horseshoe crab using its telson for righting.
Caridoid escape reaction : A rapid backward swimming response produced by abdominal flexion in many shrimp-like crustaceans. Telson movement helps direct the powerful abdominal flexion used in this escape response.
Anal lobe : A posterior extension surrounding or lying near the anus in various animals. An anal lobe is defined by its relation to the anus, not by the arthropod telson's lineage-specific anatomy.
Somite : A repeated body segment formed during the development of many animals. Unlike abdominal somites, the telson is generally not a true segmented body unit.
Swimming crab : A crab adapted for swimming, often with flattened, paddle-shaped hind legs. In swimming crabs, the telson joins uropods in the tail fan used during backward swimming.
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