Ricinulei

A ricinuleid, commonly known as a "hooded tickspider", is an invertebrate animal belonging to the order Ricinulei in the class Arachnida, in the subphylum Chelicerata of the phylum Arthropoda.

Physical description

Ricinulei range from 5 to 10 mm in length. Their most notable feature is a "hood" which can be raised and lowered over the head; when lowered, it covers the mouth and the chelicerae. Ricinulei have no eyes. The pedipalps end in pincers that are small relative to their bodies, when compared to those of the related orders of scorpions and pseudoscorpions. The heavy-bodied abdomen forms a narrow pedicel, or waist, where it attaches to the prosoma[?]. In males, the third pair of legs are modified to form copulatory organs. Malpighian tubules[?] and a pair of coxal glands[?] make up the excretory system. They have no lungs, as gas exchange takes place through the trachea.

Behavior

Ricinulei are predators, feeding on other small arthropods. Little is known about their mating habits; the males have been observed using their modified third leg to transfer a spermatophore to the female. The eggs are carried under the mother's hood, until the young hatch into six-legged "larva", which later molt into their adult forms.

Habitat

Ricinulei require dampness to survive.

As of 2000, approximately 55 species of ricinulei have been described worldwide, all in a single family which contains 3 genera.