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| Caribbean hermit crab | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Malacostraca |
| Subclass: | Eumalacostraca |
| Superorder: | Eucarida |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Infraorder: | Anomura |
| Superfamily: | Paguroidea |
| Family: | Coenobitidae |
| Genus: | Coenobita |
| Species: | C. clypeatus |
| Binomial name | |
| Coenobita clypeatus (Fabricius, 1787) |
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The Wikibook Animal Care has a page on the topic of |
The Caribbean hermit crab (Coenobita clypeatus), also known as the West Atlantic crab, the tree crab, the soldier crab, and the purple pincher (due to the distinctive purple claw), is a species of land hermit crab native to the west Atlantic, Bahamas, Belize, southern Florida[1], Venezuela, the Virgin Islands, and the West Indies.[2]
This species is one of the two land hermit crabs commonly sold in the United States as a pet, the other being the Ecuadorian hermit crab.[2][3] In captivity they can live to be over 30 years old (and over 40 years in exceptional cases).
Caribbean hermit crabs are omnivorous scavengers who live in colonies of 100 or more in inland areas.
As pets they prefer a relative humidity level between 70% and 78%, and a temperature of 24°C (75°F).
Contents |
Physical description
Coenobita clypeatus is a member of the phylum Arthropoda and the class Malacostraca. The color varies from a pale red to a dark brown or burgundy.
The eyestalks are round and white, with a black or brown stripe on the bottom. The eyes are oval in shape. The abdomen is short and fat. There are four walking legs, four tiny legs to hold the shell in place, a small pincher, a large purple pincher, and four antennae. The large claw is used to close the entrance of the shell to protect itself from predators.[1]
Although these hermit crabs live on land, they have gills, rather than lungs. The high relative humidity of their native environments, plus water carried in the shell, allows their modified gills to remain wet and thus to function properly in extracting oxygen from the air.
Anatomy
 Eyes and face |
 Antennule |
 Modified gills |
 Abdomen |
 4th leg that clasps the columella of shell |
 5th leg that holds the shell |
 The abdomen-thorax connection |
 Mouth and antennae connection |
 Claws (pincers) |
Habitat
Adult Caribbean hermit crabs can be found well inland, while juveniles begin their lives in the water and near the shore. They are a common site near homes of people. They burrow and hide under the roots of large trees.[1]
Diet
Caribbean hermit crabs are both herbivorous and scavengers. In the wild, land hermit crabs feed off of coconut trees, leftovers from humans, and scavenge dead organisms, such as fish and other crabs. Hermit crabs are able to bury their food in the sand to consume later, but other crabs may find it and consume it themselves.
In captivity, land hermit crabs are fed commercial foods which come in many varieties. Hermit crabs are also fed treats that include fruits and vegetables such as coconuts, mangos, papayas, apples, bananas, carrots, or spinach.
Shell usage and shell fights
The land hermit crab uses a shell to protect its delicate body. The shell is sometimes that of a land snail when it is young, but is usually that of a marine snail. When a marine snail dies, the soft parts decompose or are eaten and the empty shell often washes up onto the shore. The hermit crab can then find and occupy the shell. Larger shells are necessary as the crab grows, but that growth is quite slow.
Hermit crabs are very particular about their shells. Shell switching is not uncommon as the crab searches for the perfect shell. A desired characteristic of a shell is an opening about the size of the large claw, plus about 2½–3 mm (1/10 in to 1/8 in) all around (more for larger crabs). When threatened, the crab withdraws into the shell and blocks the entrance with the large claw.
Fierce shell fights can occur when the shell supply is not adequate. The loser often dies, since many hermit crabs will not release their grip on their shell until they are torn apart. The loss of limbs in shell fights is common, but may not result in death especially since the hermit crab can choose to drop (autotomize) a limb to disengage from the conflict.
Shells used by Coenobita clypeatus
When choice of shells is available, C. clypeatus seems to prefer intact undamaged shells with circular or oval openings and a smooth mother-of-pearl interior. However in a pinch, they will use whatever they can find that they can fit into, even discarded, man-made items such as plastic glasses, broken bottles or tiny one-person jam jars.
Painted shells are commonly sold for pets, but it is said that they should not be used for a pet Coenobita clypeatus because it is a potentially dangerous practice that may shorten the crab's life span. The paint will eventually chip off the shell, and the hermit crab may eat the chippings.
The West Indian Top Snail (Cittarium pica) shell is often used for its home.[1] Other snail (class Gastropoda, phylum Mollusca) shells with circular/oval openings available for their use in the wild on the coasts of the tropical Western Atlantic Ocean include :
- Superorder Vetigastropoda - Order under revision
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- Turban shells (genus Turbo, family Turbinidae):
- West Indian topshell (Cittarium pica, family Trochidae, aka the Magpie, the West Indian Topsnail, or locally known as "wilks" or "whelks". (Overfishing of this snail (Bermuda) has been known to negatively effect the Caribbean hermit crab population.) - image
- Superorder Caenogastropoda - Order Sorbeoconcha
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- Periwinkle shells (genera Littorina, Littoraria, or Echinolittorina/Nodilittorina ; family Littorinidae):
- "Tulip shell" shells (genus Fasciolaria, family Fasciolariidae):
-
- True tulip shell (Fasciolaria tulipa) - image
- Nutmeg shells (genus Trigonostoma ; family Cancellariidae):
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- Rugosa nutmeg (Trigonostoma rugosum) - image
- Tun shells (genus Tonna, family Tonnidae):
- Crown conch shells (Melongena corona, family Melongenidae) - image
- Order Pulmonata, air-breathing land snails
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- Haitian tree snail shells [also called "candy striped" or "rainbow" shells] (Liguus virgineus, family Orthalicidae) - Region: Cuba - image
Growth and molting
The Caribbean hermit crab, like all species of hermit crabs, grows through a strenuous and hazardous process called molting where the exoskeleton of the animal is shed and a new, soft exoskeleton is exposed from beneath. A molt also allows the crab to regrow lost appendages. The smallest Caribbean hermit crabs will molt many times per year, while the largest (about the size of a baseball) may only molt once every 12 to 18 months.
Before a molt, the hermit crab will attempt to eat enough to survive the molting period. It will obtain sea salt from salt water to aid in shedding the old exoskeleton and will store a supply of water. The crab may even seek out a smaller, tighter shell for easier digging or a larger shell for room to shed. Normally the molt is started by digging down into the moist substrate (with its shell) and creating a little cave. There total darkness triggers the secretion of the molting hormone ecdysone.
Over a period of up to three months (larger crabs require the most time),
- the buried, molting crab sheds the old exoskeleton in a process called ecdysis,
- lost appendages may be regrown (completely or partially),
- the new exoskeleton hardens,
- the old exoskeleton is eaten, in order to reuse the calcium and other lost nutrients while it's molting,
- the crab regains its strength and returns to the surface.
Sometimes the land hermit crab will molt on the surface where other crabs may eat the shed exoskeleton or the exposed molting crab. Circumstances that may cause a surface molt include illness, or the lack of a substrate in which the crab can bury itself.
Land hermit crab reproduction
Female land hermit crabs release fertilized eggs into the ocean. The spawning (called "washing" in the English-speaking Caribbean) occurs on certain nights, usually around August. [4] The crabs congregate en masse near certain places (called "soldier wash") on the shore. When night comes they all go to the water together, leave their shells on the shore, enter the water naked and spawn. Since they are naked they are vulnerable to a variety of predators, both terrestrial and marine, at this time. (Certain predatory fish congregate near soldier washes in August.) Once they are done "washing" the surviving adult crabs return to the land, find a shell from the many recently left by their companions and head out. There are always quite a few, well-used, unclaimed shells left in the morning - evidence of the ones that didn't make it. As for the eggs, they hatch and spend a time in the sea as free-swimming plankton. The hatchlings live in the ocean until their gills mature enough to be able to extract oxygen from air.
Once on land, the hermit crab begins to drink fresh water, but still requires salt water (sea salt) for functions like molting. After the last developmental molt, the modified gills lose the ability to process water and the crab can drown if trapped under water.
Captive C. clypeatus will not breed in an indoor environment, but have done so in an outdoor enclosure. None of the young lived past 10 days.
Spermiogenesis
The testes of the species Coenobita clypeatus contains germinal cells and non-germinative cells. The latter function in the manner of the vertebrate Sertoli cells in apparently providing nourishment, support and possibly hormones during spermiogenesis. Each Sertoli cell surrounds several germinal cells. The mitochondria, rough and smooth endoplasmic reticulum and Golgi apparatus show changes in structure when in contact with germinal cells in different stages of spermiogenesis. These changes are suggestive of active synthesis and metabolism of cellular products.[5]
External links
Hermit Crabs at the Open Directory Project
References
- ^ a b c d "Common Coastal Flora and Fauna of Vieques". National Oceanic and Atmospheric Administration (NOAA). http://mapping2.orr.noaa.gov/portal/vieques/pdfs/VCHTbook.pdf. Retrieved 2009-07-14.
- ^ a b Audrey Pavia: Hermit Crab PG.18 Retrieved July, 2009
- ^ Barren's: Hermit Crabs PG.9
- ^ Nieves-Rivera, Á. M. & E. H. Williams, Jr. (2003). "Coenobita clypeatus (Herbst) of Mona Island crustaceans". Crustaceana 76: 547–558. doi:.
- ^ Tissue Cell publication from PubMed.gov – 1980, ISSN: 0040-8166 (Print)
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