Australian land hermit crab
Encyclopedia
The Australian land hermit crab (Coenobita variabilis) is a terrestrial hermit crab
species, native to Australia
. It is a nocturnal, omnivorous crustacean. They are gregarious and thrive in tropical areas near water.
including northern Western Australia
, Northern Territory
and northern Queensland
.
length of 40 millimetres (1.6 in). They closely resemble the Pacific hermit crab (Coenobita compressus) in appearance and they both have a shortened aquatic development stage.
Australian hermit crabs are light brown to pale brown in colour, with two dark ovals on the front of the head. Their eyestalks are long and are the same colour as the body. Each claw has a dark vertical stripe. They have dark brown spots all over the legs. The abdomen is short and fat.
, Nerita
, Phasianella
, Thais, Tonna
and Turban seashells. They are also found to be fond of several varieties of land snail shells such as Aratan snail and rice snail.
As the hermit crabs grow, they must exchange their shell for a larger one. Since intact gastropod shells are not an unlimited resource, there is frequently strong competition for the available shells, with hermit crabs fighting over shells. The availability of empty shells depends on the abundance of the gastropods and hermit crabs, but most importantly on the frequency of organisms that predate on gastropods but leave the shells intact. A hermit crab with a shell which is too tight cannot grow as fast as hermit crabs with well-fitting shells, and is more likely to be eaten. Although hermit crabs need to change shells regularly, they will not abandon their old shell unless they have a larger and newer one to change into and unless they feel safe.
Hermit crab
Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the 1100 species possess an asymmetrical abdomen which is concealed in an empty gastropod shell that is carried around by the hermit crab.-Description:...
species, native to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. It is a nocturnal, omnivorous crustacean. They are gregarious and thrive in tropical areas near water.
Distribution
The Australian land hermit crab is endemic to northern parts of AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
including northern Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
and northern Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
.
Biology
The Australian land hermit crab (Coenobita variabilis) reaches a carapaceCarapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
length of 40 millimetres (1.6 in). They closely resemble the Pacific hermit crab (Coenobita compressus) in appearance and they both have a shortened aquatic development stage.
Australian hermit crabs are light brown to pale brown in colour, with two dark ovals on the front of the head. Their eyestalks are long and are the same colour as the body. Each claw has a dark vertical stripe. They have dark brown spots all over the legs. The abdomen is short and fat.
Shell preference
The preferred seashells of C. variabilis include BabyloniaBabylonia (gastropod)
Babylonia is a genus of sea snails, marine gastropod mollusks in the family Babyloniidae.-Species:According to the World Register of Marine Species , the following species with valid names are included within the genus Babylonia:...
, Nerita
Nerita
Nerita is a genus of medium-sized sea snails with a gill and an operculum, marine gastropod molluscs in the family Neritidae, the nerites.This is the type genus of the family Neritidae.-Distribution and habitat:...
, Phasianella
Phasianella
Phasianella, common name pheasant shells, is a genus of sea snails with a calcareous operculum and a colorfully patterned shell, a marine gastropod mollusc in the family Phasianellidae.-Species:Species within the genus Phasianella include:...
, Thais, Tonna
Tonna (genus)
Tonna is a genus of large sea snails, marine gastropod molluscs in the family Tonnidae, the tun or cask shells. -Species:Species within the genus Tonna include:* Tonna alanbeui Vos, 2005* Tonna allium...
and Turban seashells. They are also found to be fond of several varieties of land snail shells such as Aratan snail and rice snail.
As the hermit crabs grow, they must exchange their shell for a larger one. Since intact gastropod shells are not an unlimited resource, there is frequently strong competition for the available shells, with hermit crabs fighting over shells. The availability of empty shells depends on the abundance of the gastropods and hermit crabs, but most importantly on the frequency of organisms that predate on gastropods but leave the shells intact. A hermit crab with a shell which is too tight cannot grow as fast as hermit crabs with well-fitting shells, and is more likely to be eaten. Although hermit crabs need to change shells regularly, they will not abandon their old shell unless they have a larger and newer one to change into and unless they feel safe.