Dromiidae is a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of 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, often referred to as sponge crabs. They are small or medium-sized crabs which get their name from the ability to shape a living sponge into a portable shelter for themselves. A sponge crab cuts out a fragment from a sponge and trims it to its own shape using its claw

Claw

A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...

s. The last two pairs of legs

Arthropod leg

The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...

 are shorter than other legs and bend upward over the crab's 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...

, to hold the sponge in place. The sponge grows along with the crab, providing a consistent shelter.

The family Dromiidae contains the following subfamilies and genera:

Dromiinae De Haan, 1833

• Alainodromia McLay, 1998
• Ameridromia † Blow & Manning, 1996
• Ascidiophilus Richters, 1880
• Austrodromidia McLay, 1993
• Barnardomia McLay, 1993
• Conchoecetes Stimpson, 1858
• Cryptodromia Stimpson, 1858
• Cryptodromiopsis Borradaile, 1903
• Desmodromia McLay, 2001
• Dromia
  Dromia
  Dromia is a genus of crabs in the family Dromiidae. It contains 6 extant species:*Dromia bollorei Forest, 1974*Dromia dormia *Dromia erythropus *Dromia marmorea Forest, 1974...
  
  Weber, 1795
• Dromidia Stimpson, 1858
• Dromidiopsis Borradaile, 1900
• Dromilites † H. Milne-Edwards, 1837
• Epigodromia McLay, 1993
• Epipedodromia André, 1932
• Eudromidia Barnard, 1947
• Exodromidia Stebbing, 1905
• Foredromia McLay, 2002
• Fultodromia McLay, 1993
• Haledromia McLay, 1993
• Hemisphaerodromia Barnard, 1954
• Homalodromia Miers, 1884
• Kerepesia † Müller, 1976
• Kromtitis † Müller, 1984
• Lamarckdromia Guinot & Tavares, 2003
• Lauridromia McLay, 1993
• Lewindromia Guinot & Tavares, 2003
• Lucanthonisia † Van Bakel, Artal, Fraaije & Jagt, 2009
• Mclaydromia Guinot & Tavares, 2003
• Metadromia McLay, 2009
• Moreiradromia Guinot & Tavares, 2003
• Noetlingia † Beurlen, 1928
• Paradromia Balss, 1921
• Petalomera Stimpson, 1858
• Platydromia Brocchi, 1877
• Pseudodromia Stimpson, 1858d
• Speodromia Barnard, 1947
• Stebbingdromia Guinot & Tavares, 2003
• Sternodromia Forest, 1974
• Stimdromia McLay, 1993
• Takedromia McLay, 1993
• Tumidodromia McLay, 2009
• Tunedromia McLay, 1993

Hypoconchinae Guinot & Tavares, 2003

• Hypoconcha Guérin-Méneville, 1854

Sphaerodromiinae Guinot & Tavares, 2003

• Eodromia McLay, 1993
• Frodromia McLay, 1993
• Sphaerodromia Alcock, 1899