The family Homolidae, known as carrier crabs or porter crabs, contains 14 genera of marine crab

Crab

True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

s. They mostly live on the continental slope and continental shelf

Continental shelf

The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

, and are rarely encountered. Members of the Homolidae have their fifth pereiopods (last pair of walking legs) in a sub-dorsal position, which allows them to hold objects in place over the rear half of the carapace

Carapace

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...

. The objects carried include sponges, black coral

Black coral

Black corals are a group of deep water, tree-like corals related to sea anemones. They are also found in rare dark shallow water areas such as New Zealand's Milford Sound where they can be viewed from an underwater observatory. They normally occur in the tropics...

s and gorgonians, and this is behaviour may be a defence mechanism against predators. Some species have been observed carrying living sea urchin

Sea urchin

Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...

s in a symbiotic

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 relationship which allows them to benefit from the protection of the urchin's dangerous spikes.

Genera

A total of 14 genera are currently recognised in the family:

• Dagnaudus Guinot & Richer de Forges, 1995
• Gordonopsis Guinot & Richer de Forges, 1995
• Homola Leach, 1816
• Homolax Alcock, 1899
• Homolochunia Doflein, 1904
• Homologenus A. Milne-Edwards, in Henderson, 1888
• Homolomannia Ihle, 1912
• Ihlopsis Guinot & Richer de Forges, 1995
• Lamoha Ng, 1998
• Latreillopsis Henderson, 1888
• Moloha Barnard, 1947
• Paromola Wood-Mason & Alcock, 1891
• Paromolopsis Wood-Mason & Alcock, 1891
• Yaldwynopsis Guinot & Richer de Forges, 1995

See also

• Paromola cuvieri
  Paromola cuvieri
  Paromola cuvieri is a species of crab in the family Homolidae. It occurs in the eastern Atlantic Ocean and the Mediterranean Sea, from Angola to Norway and the Northern Isles. It is demersal, occurring at depths of .-References:...
  
  , found in the North Atlantic and Mediterranean Sea
  Mediterranean Sea
  The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
  
  
• Homola barbata
  Homola barbata
  Homola barbata is a species of crab in the family Homolidae.-Description:They usually have squarish carapaces with forward-pointing spines along the upper front edges. The animal's chelipeds are shorter than their other legs...
  
  , Atlantic Ocean
  Atlantic Ocean
  The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
  
   and Mediterranean Sea
  Mediterranean Sea
  The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...