Glossary of Terms related to Hermit Crabs


Abdomen: Region of the body furthest from the mouth. In insects, the third body region behind the head and thorax.

Antennae: sense organs also known as 'feelers' help the hermit crab smell and taste. A hermit crab has two pairs of anteannae at the front of their head, with two being long and two being short. The long pair are called antennas and the short pair antennules. Antennas are used to touch and sense other hermit crabs and objects.The antennules are what a hermit crab uses to smell and taste.

Antennule : a small antenna, esp. one of the foremost pair of a crustacean. 1

Anus: Located at the end of the hermit crab's abdomen. (Fox, S. 2000 p.13)

Appendages : limbs

Atoll: (Pronounced a-tahl). Type of island that is formed when the top of an underwater volcano that was once above the water sinks below the surface, leaving only the coral reef and sandbars in a ring around a lagoon.

Autotomy: also called Self-amputation, the ability of certain animals to release part of the body that has been grasped by an external agent.EB



carcinology n. study of crustaceans. carcinomorphic, a. like a crab or crustacean.

C.C. : 1. CrazyCrab: Now known as Aussie Hermits, a land hermit crab of the species C. variabilis; 2. Coenobita clypeatus

Carapace : "The portion of cepalthorax that covers the top of the crab forms a hard protective shield called the carapace" (Fox, S. 2000 p.13)

Carnivorous : an animal that eats meat

Cepalthorax : The hermit crab's head, which contains its mouth, eyes and antennae, is fused to its thorax and is known as the cepalthorax. The crab's five pair of legs are attached to the thorax. The portion of the cepalthorax that covers the top of the crab forms a hard protective shield called the carapace

Chela: (Pronounced kee-la) a pincer

Cheliped : (Pronounced kee-li-ped) chelipeds (chela="claw" and ped="foot").. Also called grasping claws because of the non-aggressive ways they are used, the chelipeds are what a hermit crab uses to grip while climbing and protect during a crab fight. When eating, you will notice a hermit crab hold the food with one cheliped, and break the food off with the other, passing it to the maxillipeds. The left claw is usually (depending on species) used for climbing or defence. When a hermit crab withdraws within its shell it will use its larger claw to block the entrance to the shell. The right claw is usually used for eating and climbing. Cheliped - (in decapod crustaceans) either of the pair of appendages bearing a chela. 2.

Chitin : (Pronounced KY-tin) In arthropods the chitinous shell, or exoskeleton, covers the surface of the body, does not grow, and is periodically cast off (molted). After the old shell is shed, a new, larger shell is secreted by the epidermis, providing room for future growth. The chitin is rigid except between some body segments and joints where it is thin and allows movement of adjacent parts. 3

Clypeatus: (Pronounced ) shield shaped

Coenobita: (pronounced 'seen-oh-bit-a') Family of terrestrial (land-based) hermit crabs.

Compound Eye: Photoreceptor of Arthropods that consists of several omatadia. It has no lid but is covered with exoskeleton.

Compressus: From the word compress [latin]. In Coenobita compressus it may have been used to describe the 'compressed' eye shape of a C. compressus land hermit crab.

Crustacean : a class of mainly aquatic animals including lobsters, crabs, shrimps, prawns etc 4

Cuticle -- In animals, a multilayered, extracellular, external body covering, usually composed of fibrous molecules such as chitin or collagen, and sometimes strengthened by the deposition of minerals such as calcium carbonate.



Detritus: (Pronounced dee-triy-tis). Decomposing organic material


Ecdysis: (Pronounced ek-diy-sis). Stage in athropod moulting in which the old exoskeleton is shed and the new enlarged with water and/or air.

Ecysone: (pronounced ek-diy-son). In insects, crustaceans ando ther arthropods, the hormone that directly affects the epidermal cells during moulting.

Ecuadorian hermit crab aka E's : hermit crab that comes from Ecuador of the species Coenobita compressus. Visit the crab species site

Epicuticle: The waxy outer layer of the Arthropod exoskeleton

Exoskeleton : "The crab's exoskeleton is made from layers of protein and chitin. The exoskeleton, or cuticle, is hardened by calcium carbonate... The exoskeleton protects the animal and provides points of attachment for the muscles to move the appendages. It helps impede water loss, although a crab still slowly loses water across its exoskeleton." (Fox, S. 2000 p.11)



Feces: Digestive waste

Feeding Appendages: see Maxillipeds

Fifth legs : small legs that are kept hidden within the shell. Used to maneuver the shell and hold itself within the shell.



Gastroliths: Deposit of calcium salts made in the stomach of many crustaceans during the period between moults. It may be used to store calcium needed in the new exoskeleton.

Gills : 1. A hermit crab's gills are enclose din the branchial chamber, which functions as a lung. The branchial chamber is on the sides of the thorax, above the crab's legs. 2. gill -- In aquatic animals, highly vascularized tissues with large surface area; these are extended out of the body and into the surrounding water for gas exchange.

Gonoduct: (Gah-no-dukt). Any duct that generally transfers eggs or sperm.

Gonopore :

1. an opening through which eggs or sperm are released, esp. in invertebrates. 5
2. any opening between the reproductive system and the outside.



Hairs: "The long hairs that you see between the joint of your crab's legs, on the maxillipeds, along the inside of some appendages, and near its mouth are called setae. Unlike the hair that grows on yor head, setae do not grow from hair follicles. They are actually extensions of the crab's cuticle. When a crab molts its exoskeleton, these "hairs" are also shed as projections of the exoskeleton. (Fox, S. 2000 p.12)


Invertebrate : creatures without a backbone 6



KritterKeeper (KK) : Name of the plastic tanks manufactured by Lees that are the most well-known type available in the US. Many people adopted calling all plastic tanks KK


Larvae : stage of development

Larval stages of Development : stages hermit crab larvae go through before progressing to the next stage of development



Maxillipeds : (Pronounced maks-il-li-ped) also known as feeding appendages, maxillipeds are very small appendages near your crab's mouth. They are like tiny little hands that take food from the chelipeds and feed the foodstuffs within the very small mouth. Maxillipeds are also used to groom itself and you will often see them when you handfeed your hermit crab.

Megalops: (Pronounced meg-a-lahps) Larval stage following the zoea larva. Post-larva.

Metamorphoses, Metamorphosed :

Molting/Moulting :

1. a process in which the exoskeleton, or outer skin, is shed and a new exo is grown. It is also a time during which lost limbs are regenerated/regrown and your hermit crab will grow slightly as the new tissues swell with fluids and then harden with the aid of chitin.

2. The hormonally-controlled process of shedding one cuticle (or exoskeleton) in order to allow growth of the organism and the subsequent replacement of the cuticle.



Nocturnal : Inactive during day, active at night. Creatures such as owls are nocturnal, where they sleep during the day and hunt for food at night. In the heat of the day, hermit crabs hide beneath foliage/leaf litter or in trees and sleep, then after sundown you can see hermit crabs on the beaches in search of fish washed up on the beach, and other carrion.



Periopod : describes the four pairs of legs which are appendages of the thorax. Includes the second and third pairs which are used for walking. The fourth and fifth which are small and usually hidden within the shell. The fourth and fifth legs are used to maneuver the shell and hold itself within the shell.

Phylogeny: (Pronounced fi-lah-je-nee). The evolutionary relationships between groups of organisms.

Plankton : Mixture of crustacea types that floats in the water 9

Pleopod : leg of a crab 7. "The pleopods are small appendages located on the left side of the crab's abdomen. A female crab attaches her eggs to the fine setae on her pleopods using a gluelike substance. Male land hermit crabs also have pleopods, but they are much smaller and not nearly as hairy.

Proecydysis (Pronounced pro-ek-diy-sis). The first stage of Arthropod molting in which the body prepares to shed the exoskeleton. In Crustaceans, the blood absorbs calcium from the exoskeleton and makes gastroliths.

Protocuticle: The inner layer of Arthropod exoskeletons that lies just under the epicuticle

Purple Pincer/Claw Hermit Crab : hermit crab that is distinguished by a purple claw and round eyes, as opposed to compressed eyes of Ecuadorian (E) crabs. Visit the crab species



Regeneration. Ability to reproduce a severed body part.


Sand Dollar: The common name for certain irregular echinoids (Echinodermata)

Setae : The long hairs that grow between the joints of your crab's legs, on the maxillipeds, along the inside of some appendages, and near its mouth are called setae. Unlike the hair that grows on your head, setae do not grow from hair follicles. They are actually extensions of the crab's cuticle. When a crab molts its exoskeleton, these "hairs" are also shed as projections of the exoskeleton." (Fox, S. 2000 p.12)


Telson (Pronounced tel-son) A medial section at the very posterior of most Arthropods: it bears the anus.


Uropods : "At the tip of a crab's abdomen are small appendages called uropods. Although you will never see them, they perform an important function. The uropods hook onto the spiral of the shell and help the crab to grip its shell."


Variabilis - Changeable [latin]

Vascular -- Refers to a network of tubes which distribute nutrients and remove wates from the tissues of the body. Large multicellular animals must rely on a vascular system to keep their cells nourished and alive.





Zoea/Zoeae: (Pronounced zo-ee-a).

1. Any of the free-swimming larva of certain crustaceans, as the crab, having rudimentary legs and a spiny carapace. 8

2. Larval stage that follows the 'protozoea'.



Fox, Sue (2000) Hermit Crabs : Complete Pet Owner's Guide. Barrons Books : N.Y.

Info Please Dictionary and Encyclopedia References

1 : [ URL: http://www.infoplease.com/ipd/A0318957.html ]
2 : [ URL: http://www.infoplease.com/ipd/A0369929.html ]
3 : [ URL: http://www.infoplease.com/ce6/sci/A0811974.html ]
4 : [ URL: http://www.infoplease.com/ce5/CE013411.html ]
5 : [ URL: http://www.infoplease.com/ipd/A0460191.html ]
6 : [ URL: http://www.infoplease.com/ce5/CE025873.html ]
7 : [ URL: http://www.infoplease.com/ipd/A0592398.html ]
8 : [ URL: http://www.infoplease.com/ipd/A0583549.html ]
9: [ URL: http://www.umassd.edu/Public/People/Kamaral/thesis/plankton.html


Introduction to the Arthropoda. . . the REAL rulers of the Earth. . .

 Updated March 26, 2005

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