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.
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]
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]
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]
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