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Pedipalps contain sensitive chemical detectors and function as taste and smell organs, supplementing those on the legs. [2] In sexually-mature male spiders, the final segment of the pedipalp, the tarsus, develops a complicated structure (sometimes called the palpal bulb or palpal organ) that is used to transfer sperm to the female seminal ...
They are unusual in that they do not transfer sperm directly, for example via a penis. Instead the males transfer it to specialized structures (palpal bulbs) on the pedipalps and then meander about to search for a mate. [17] These palps are then introduced into the female's epigyne. This was first described in 1678 by Martin Lister. In 1843 it ...
In basal chelicerates, the pedipalps are unspecialized and subequal to the posterior pairs of walking legs. [10] However, in sea spider and arachnids, the pedipalps are more or less specialized for sensory [ 12 ] or prey-catching function [ 10 ] – for example scorpions have pincers [ 20 ] and male spiders have bulbous tips that act as ...
Pedipalp (plural pedipalps or pedipalpi; also called just palp): The second appendage of the cephalothorax in front of the first leg; bears the palpal bulb in male spiders; [10] see segments, see also Pedipalp
An example of specialization of these asymmetrical chelae can be seen in the Alpheus heterochaelis, the bigclaw snapping shrimp. The enlarged snapping claws of these shrimp are capable of snapping shut with such force to shoot a jet of water and create a loud popping noise, which they use to deter predators and other members of their species.
The evolutionary change from muscular to hydraulic movement of palpal bulbs is hypothesised to have been driven by the more complex movements this made possible. With only two muscles available, the degree of movement is limited; for example the maximum reported rotation is 300° with muscle movement as opposed to 540° with hydraulic movement.
The pedipalps generally consist of an immobile "hand" and mobile "finger", the latter controlled by an adductor muscle. Members of the clade Iocheirata, which contains the majority of pseudoscorpions, are venomous , with a venom gland and duct usually located in the mobile finger; the venom is used to immobilize the pseudoscorpion's prey.
Harvestmen pedipalps are anatomically laid out like the legs, the difference being that the proximal metatarsus and distal tarsus are merged, and simply called tarsus. [1] Pedipalpal identity is conferred by the Hox gene labial ; reducing the expression of this gene transforms pedipalps into chelicerae.