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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 ...
The cephalothorax, also called prosoma, is composed of two primary surfaces: a dorsal carapace and a ventral sternum.Most external appendages on the spider are attached to the cephalothorax, including the eyes, chelicerae and other mouthparts, pedipalps and legs.
The palpal bulb of a mature male spider is borne on the last segment of the pedipalp. This segment usually has touch-sensitive hairs (setae) with nerves leading to them. The bulb itself is entirely without nerves, and hence without sensory organs and muscles, since these depend on nerves for their functioning, [ 1 ] although some spiders have ...
Pedipalp and leg of a female spider from the underside; the coxa of the pedipalp is heavily modified to form the maxilla. Segments or articles of the legs and pedipalps: Coxa (plural coxae): First leg segment, between body and trochanter; the coxa of the pedipalp is heavily modified to form the maxilla or endite
Diagram of a spider leg and pedipalp – the pedipalp has one fewer segment. Arachnid legs differ from those of insects by the addition of two segments on either side of the tibia, the patella between the femur and the tibia, and the metatarsus (sometimes called basitarsus) between the tibia and the tarsus (sometimes called telotarsus), making a total of seven segments.
Somite 2 has a pair of pedipalps that in most sub-groups perform sensory functions, while the remaining four cephalothorax segments (somite 4 to 6) have pairs of legs. [10] In basal forms the ocular somite has a pair of compound eyes on the sides and four pigment-cup ocelli ("little eyes") in the middle. [ 12 ]
Pedipalp anatomy varies strongly with species, with configurations often conforming to a particular style of prey capture. The pedipalps of some genera such as Euphrynicus are extremely long, and free of spines until near the extreme distal end of the appendage.
Observations suggesting that there might be silk-producing organs on the feet of the zebra tarantula (Aphonopelma seemanni) led to questions about the origins of spinnerets. It was hypothesised that spinnerets in spiders were originally used as climbing aids on the feet and evolved and were used for webmaking at a later time.