Emerita is a small genus of decapod crustaceans, known as mole crabs, sand crabs, sand bugs, or sand fleas. These small animals burrow in the sand in the swash zone and use their antennae for filter feeding.
A fiddler crab, sometimes known as a calling crab, may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae. A smaller number of ghost crab and mangrove crab species are also found in the family Ocypodidae. This entire group is composed of small crabs, the largest being slightly over two inches (5 cm) across. Fiddler crabs are found along sea beaches and brackish intertidal mud flats, lagoons and swamps. Fiddler crabs are most well known for their sexually dimorphic claws; the males' major claw is much larger than the minor claw, while the females' claws are both the same size.
Mictyris is a genus of brightly coloured crabs, placed in its own taxonomical family, the Mictyridae. It inhabits the central Indo-West Pacific region. These crabs congregate on mud flats or beaches in groups of a few thousand, and filter sand or mud for microscopic organisms. They congregate during low tide, and bury themselves in the sand during high tide or whenever they are threatened. This is done in wet sand, and they dig in a corkscrew pattern, leaving many small round pellets of sand behind them.
Portunidae is a family of crabs which contains the swimming crabs.
Coenobita perlatus is a species of terrestrial hermit crab. It is known as the strawberry hermit crab because of its reddish-orange colours. It is a widespread scavenger across the Indo-Pacific, and is also traded to hobby aquarists.
Sand bubbler crabs are crabs of the genera Scopimera and Dotilla in the family Dotillidae. They are small crabs that live on sandy beaches in the tropical Indo-Pacific. They feed by filtering sand through their mouthparts, leaving behind balls of sand that are disintegrated by the incoming high tide.
Macrophthalmus is a genus of crabs which are widespread across the Indo-Pacific. It contains the following species :
Calappidae is a family of crabs containing 16 genera, of which 7 are only known as fossils:
Palicoidea is a superfamily of crabs, comprising the two families Crossotonotidae and Palicidae. Together, they contain 13 genera, including two genera in the Palicidae known only from fossils. The two families were previously treated as two subfamilies in a Palicidae of wider circumscription.
Mictyris longicarpus, the light-blue soldier crab, is a species of crab that lives on sandy beaches from the Bay of Bengal to Australia; with other members of the genus Mictyris, it is "one of the most loved crabs in Australia". Adults are 25 mm (1 in) across, white, with blue on their backs, and hold their claws vertically. They feed on detritus in the sand, leaving rounded pellets of discarded sand behind them. The males may form into large "armies" which traverse the beach at low tide, before the crabs dig into the sand to wait for the next low tide. Typically found across the road from Nana's house in Hollywell.
Pachygrapsus is a genus of small shore crabs. Recent genetic data suggest this genus to be possibly polyphyletic.
Liomera is a genus of crabs in the family Xanthidae, containing the following species:
Atergatis is a genus of crabs in the family Xanthidae, containing the following species:
The Panopeidae are a family containing 26 genera of morphologically similar crabs, often known as "mud crabs". Their centers of diversity are the Atlantic Ocean and eastern Pacific Ocean.
Around 65 species of crab occur in the waters of the British Isles. All are marine, with the exception of the introduced Chinese mitten crab, Eriocheir sinensis, which occurs in fresh and brackish water. They range in size from the deep-water species Paromola cuvieri, which can reach a claw span of 1.2 metres, to the pea crab, which is only 4 mm (0.16 in) wide and lives inside mussel shells.
Dotilla myctiroides is a species of sand bubbler crab found on tropical shores and mud-flats of India, Thailand, Malaysia, Indonesia, Singapore and Sri Lanka. They breed throughout the year but activity peaks during the monsoons. This species builds a burrow, called an "igloo", in unstable sand as well as in well-drained and firm sand. In building the igloo, the crab excavates sand and forms it into spherical pellets. These pellets are used to form a circular wall and roof in the burrow. The resulting structure holds a small amount of air in addition to the crab itself.
Calappilia is an extinct genus of box crabs belonging to the family Calappidae. The type species of the genus is Calappilia verrucosa.
Dardanus deformis is a species of nocturnal hermit crab that is found in the Indo-Pacific. Its common name is pale anemone hermit. The species is known to transfer sea anemones from one shell to another when it moves to a different shell. It can be kept in an aquarium.
Austruca is a genus of indo-west Pacific fiddler crabs in the family Ocypodidae. There are about 13 described species in this genus.
