The Decapoda or decapods are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crabs, lobsters, crayfish, shrimp, and prawns. Most decapods are scavengers. The order is estimated to contain nearly 15,000 species in around 2,700 genera, with around 3,300 fossil species. Nearly half of these species are crabs, with the shrimp and Anomura including hermit crabs, porcelain crabs, squat lobsters making up the bulk of the remainder. The earliest fossil decapod is the Devonian Palaeopalaemon.
Squat lobsters are dorsoventrally flattened crustaceans with long tails held curled beneath the cephalothorax. They are found in the two superfamilies Galatheoidea and Chirostyloidea, which form part of the decapod infraorder Anomura, alongside groups including the hermit crabs and mole crabs. They are distributed worldwide in the oceans, and occur from near the surface to deep sea hydrothermal vents, with one species occupying caves above sea level. More than 900 species have been described, in around 60 genera. Some species form dense aggregations, either on the sea floor or in the water column, and a small number are commercially fished.
Slipper lobsters are a family (Scyllaridae) of about 90 species of achelate crustaceans, in the Decapoda clade Reptantia, found in all warm oceans and seas. They are not true lobsters, but are more closely related to spiny lobsters and furry lobsters. Slipper lobsters are instantly recognisable by their enlarged antennae, which project forward from the head as wide plates. All the species of slipper lobsters are edible, and some, such as the Moreton Bay bug and the Balmain bug are of commercial importance.
Nephrops is a genus of lobsters comprising a single extant species, Nephrops norvegicus, and several fossil species. It was erected by William Elford Leach in 1814, to accommodate N. norvegicus alone, which had previously been placed in genera such as Cancer, Astacus or Homarus. Nephrops means "kidney eye" and refers to the shape of the animal's compound eye.
Thalassinidea is a former infraorder of decapod crustaceans that live in burrows in muddy bottoms of the world's oceans. In Australian English, the littoral thalassinidean Trypaea australiensis is referred to as the yabby, frequently used as bait for estuarine fishing; elsewhere, however, they are poorly known, and as such have few vernacular names, "mud lobster" and "ghost shrimp" counting among them. The burrows made by thalassinideans are frequently preserved, and the fossil record of thalassinideans reaches back to the late Jurassic.
Axiidea is an infraorder of decapod crustaceans. They are colloquially known as mud shrimp, ghost shrimp, or burrowing shrimp; however, these decapods are only distantly related to true shrimp. Axiidea and Gebiidea are divergent infraoders of the former infraorder Thalassinidea. These infraorders have converged ecologically and morphologically as burrowing forms. Based on molecular evidence as of 2009, it is now widely believed that these two infraorders represent two distinct lineages separate from one another. Since this is a recent change, much of the literature and research surrounding these infraorders still refers to the Axiidea and Gebiidea in combination as "thalassinidean" for the sake of clarity and reference. This division based on molecular evidence is consistent with the groupings proposed by Robert Gurney in 1938 based on larval developmental stages.
Upogebiidae is a family of mud shrimp crustaceans belonging to the infraorder Gebiidea, within the order Decapoda. They are infauna, living their entire adult lives in seafloor burrows. Over 100 species have been identified, with different species often highly specialized for different types of substrate, even including sea sponges or coral. They are filter feeders, although some species also deposit feed.
Callianassa is a genus of mud shrimps, in the family Callianassidae. Three of the species in this genus have been split off into a new genus, Pestarella, while others such as Callianassa filholi have been moved to Biffarius.
Gilvossius tyrrhenus is a species of thalassinidean crustacean which grows to a length of 70 mm (2.8 in). It lives in burrows in shallow sandy parts of the sea-bed in the Mediterranean Sea and northern Atlantic Ocean. It is the most common thalassinidean in the Mediterranean, and has been used as bait by fishermen for at least 200 years.
Pestarella is a genus of thalassinidean crustacean erected in 2003 from former members of the genus Callianassa. It is distinguished from Callianassa by the rounded, rather than squarish telson, and by the absence of the first two pleopods in males. The genus contains the following species:
Upogebia deltaura is a species of mud lobster from the Atlantic Ocean and Mediterranean Sea.
Gebiidea is an infraorder of decapod crustaceans. Gebiidea and Axiidea are divergent infraoders of the former infraorder Thalassinidea. These infraorders have converged ecologically and morphologically as burrowing forms. Based on molecular evidence as of 2009, it is now widely believed that these two infraorders represent two distinct lineages separate from one another. Since this is a recent change, much of the literature and research surrounding these infraorders still refers to the Axiidea and Gebiidea in combination as "thalassinidean" for the sake of clarity and reference. This division based on molecular evidence is consistent with the groupings proposed by Robert Gurney in 1938 based on larval developmental stages.
Matutidae is a family of crabs, sometimes called moon crabs, adapted for swimming or digging. They differ from the swimming crabs of the family Portunidae in that all five pairs of legs are flattened, rather than just the last pair, as in Portunidae. Crabs in the Matutidae are aggressive predators.
Lepidophthalmus turneranus, the Cameroon ghost shrimp, is a species of "ghost shrimp" or "mud lobster" that lives off the coast of West Africa. It occasionally erupts into dense swarms, one of which resulted in the naming of the country Cameroon.
Neoglyphea inopinata is a species of glypheoid lobster, a group thought long extinct before Neoglyphea was discovered. It is a lobster-like animal, up to around 15 centimetres (5.9 in) in length, although without claws. It is only known from 17 specimens, caught at two sites – one at the entrance to Manila Bay in the Philippines, and one in the Timor Sea, north of Australia. Due to the small number of specimens available, little is known about the species, but it appears to live up to five years, with a short larval phase. A second species, previously included in Neoglyphea, is now placed in a separate genus, Laurentaeglyphea.
Excoecaria agallocha, a mangrove species, belongs to the genus Excoecaria of the family Euphorbiaceae. The species has many common names, including blind-your-eye mangrove, blinding tree, buta buta tree, milky mangrove, poisonfish tree, and river poison tree. Most of the names refer to its toxic properties or its propensity to cause blindness when its latex comes into contact with the eyes.
Acanthaxius is a genus of mud lobster native to the Indo-Pacific oceans. It has a slender rostrum which is longer than the eyestalks, is spinose and has seven spines and has a depth range of 228–438 metres (748–1,437 ft).
The violet vinegar crab is a swimming crab species in the genus Episesarma. Distributed all over marine and brackish waters of Indo-West Pacific regions. It is harvested by many local fishermen for rich proteinaceous food.
Notopus dorsipes is a species of frog crab from the family Raninidae which has an Indo-Pacific distribution and which has recently spread into the eastern Mediterranean. It is the only extant species in the genus Notopus.
Thalassina anomala, known as the scorpion mud lobster, is a species of crustacean in the family Thalassinidae.
