Ultimate legs
Pair of modified rear legs unique to centipedes
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Ultimate legs are a pair of modified rear legs unique to centipedes. Although they do not aid in locomotion, ultimate legs possess a variety of uses, and their morphology varies accordingly.
| Ultimate legs | |
|---|---|
| |
| Details | |
| Synonyms | Anal legs, caudal legs, terminal legs |
| Origins | Legs |
| Function | Varied: defensive postures, mating rituals, anchoring |
| Anatomical terminology | |
Sexual dimorphism is frequently present.[1][2][3][4]
Usage
As a defence against predators
In many species, ultimate legs are used in warning postures to scare off predators. The ultimate legs are raised, splayed, and sometimes waved back and forth.[1][2] The presence of spines on the ultimate legs of some species also serves a defensive role- as Lewis & Kronmüller (2015) put it, "a predator approaching from behind would come into contact with a battery of spines."[2]
As a means of sound production
Members of the genus Alipes, as well as some other centipedes, stridulate their leaf-like ultimate legs, possibly as a way to warn off predators, or as a distraction by encouraging the predator to focus on the legs, which would then be autotomized to help the centipede escape.[2]
In some of those species, including Alipes grandidieri and Rhysida immarginata togoensis, the legs continue to stridulate for over half a minute after being detached.[2]
For suspension
Some species use their ultimate legs to hang or anchor themselves from trees or other desired objects. This has been recorded as playing a role in predation; the centipede suspends itself in the air and swings back and forth to capture prey.[2]
In contact with other centipedes
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Before mating, many species of Scolopendrid centipedes interlock ultimate legs. A similar behaviour has been recorded in ordinary meetings, wherein each centipede grasps the other's trunk with its ultimate legs. This possibly serves as a way to defuse aggression, and in some species may be held for several minutes.[2]
During mating, Scutigera coleoptrata raise and lower their ultimate legs, along with their antennae.[3]