Ashley Cameron, Portland State University
Invertebrate Zoology, Dr. Masta
Abstract Pagurus samuelis is a common intertidal species of hermit crab along the Pacific coast, occurring from Alaska to Mexico. It can be identified by the blue bands around the end of its walking legs. P. samuelis is in the family Paguridae, consisting of “right-handed” hermit crabs in which the right cheliped is larger and the abdomen coils clockwise. P. samuelis is a detritovore, but will opportunistically feed upon living plants or animal matter. Unlike other crustaceans, hermit crabs require the shell of another organism to protect their soft abdomen, which is not covered by the same chitinous exoskeleton …show more content…
Family Paguridae is classified as an anomuran, which is in contrast to the brachyurans, or “true crabs”. Brachyurans have a reduced abdomen that is curled underneath the body and protected by the chitinous carapace. The hermit crab has a unique abdomen – it is unprotected by the carapace that covers the hermit 's cephalo-thorax. The abdomen of P. samuelis coils to the right, and can fit shells that coil clockwise, which is necessary for protecting the soft body. Like other crustaceans, P. samuelis has five pairs of appendages on its cephalon, including antennules (chemosensory function), antennae (for touch), mandibles and and two pairs of maxillae.(13) The compound eyes are on stalks. The thorax includes eight appendages, of which the first pair are modified into claws, or chelae/chelipeds. Like other anomurans, but unlike brachyurans, the hermit crab has its fifth pair of walking legs greatly reduced and uses them for keeping its gills clean, while the fourth pair of walking legs are used for holding on to the inside of its shell. In hermit crabs, only two pairs of walking legs are used for locomotion, along with the chelipeds.(13) There are also appendages on the abdomen called pleopods which are used by the female to attach and carry fertilized …show more content…
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