| Polycheles typhlops | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Family: | Polychelidae |
| Genus: | Polycheles |
| Species: | P. typhlops |
| Binomial name | |
| Polycheles typhlops | |
| Synonyms [3] | |
| |
Polycheles typhlops is a species of blind, deep water decapod crustacean with a cosmopolitan distribution. It is "one of the dominant and most characteristic crustaceans in deep-sea communities of the Mediterranean Sea". [4]
Adult P. typhlops reach a total length of 50–100 millimetres (2.0–3.9 in), [4] from the tip of the rostrum to the end of the telson. This excludes the greatly elongated first pair of pereiopods which are normally held with the first three segments close to the side of the thorax, and the remainder held horizontal above the level of the animal's body, with the tips of the claws not exceeding the tip of the rostrum. [5] This is thought to be an adaptation to predation while partly buried in the sediment. [5] The usual colour of the exoskeleton is whitish, orange or yellow, with the fertilised eggs matching the colour of the pleon where they are brooded. [4]
As in other polychelids, and as implied by the generic names Polycheles and Pentacheles, all five pairs of pereiopods bear claws.
Polycheles typhlops may be distinguished from closely related species by a number of characteristics, including the presence of an indentation around the orbit of the eye, 12–15 spines on each side of the carapace, a forward-pointing spine on the back of each of the second to fifth segments of the pleon, and two longitudinal ridges on each uropod. [6] Only one other polychelid species is known to occur in the Mediterranean Sea, although four different species of larva have been found there. [7]
Polycheles typhlops lives in deep water throughout the Indo-Pacific, and on both sides of the Atlantic Ocean, [4] including the Mediterranean Sea, the type specimen having been caught off Sicily. [3]
The species' depth distribution is less clear, with different authors citing depths of 350–900 metres (1,150–2,950 ft), [8] 300–2,000 metres (980–6,560 ft), [7] 450–2,000 metres (1,480–6,560 ft), [4] 77–2,055 metres (253–6,742 ft), [3] and 600–1,400 metres (2,000–4,600 ft). [9] It is reported to be most abundant at depths of 750 metres (2,460 ft), [9] 500–1,000 metres (1,600–3,300 ft), [7] or 900–1,300 metres (3,000–4,300 ft). [10] There are known to be both seasonal and geographical variations in depth, which may help to explain the variation. [4]
P. typhlops probably acts as an ambush predator, hiding buried in the sediment with its claws raised above the surface. [5] Its main prey are bony fish and other crustaceans, such as shrimp, mysids and amphipods. [9]
Dendrobranchiata is a suborder of decapods, commonly known as prawns. There are 540 extant species in seven families, and a fossil record extending back to the Devonian. They differ from related animals, such as Caridea and Stenopodidea, by the branching form of the gills and by the fact that they do not brood their eggs, but release them directly into the water. They may reach a length of over 330 millimetres (13 in) and a mass of 450 grams (1.0 lb), and are widely fished and farmed for human consumption.
The Decapoda or decapods are an order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfish, shrimp, and prawns. Most decapods are scavengers. The order is estimated to contain nearly 15,000 extant 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 fossils of the group date to the Devonian.
Reptantia is a clade of decapod crustaceans named in 1880 which includes lobsters, crabs and many other well-known crustaceans.
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.
Anomura is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans include the word crab, all true crabs are in the sister group to the Anomura, the Brachyura.
Astacidea is an infraorder of decapod crustaceans including lobsters, crayfish, and their close relatives.
The decapod is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various groups these may be reduced or missing. They are, from head to tail:
Metanephrops challengeri is a species of slim, pink lobster that lives around the coast of New Zealand. It is typically 13–18 cm (5–7 in) long and weighs around 100 g (3.5 oz). The carapace and abdomen are smooth, and adults are white with pink and brown markings and a conspicuous pair of long, slim claws. M. challengeri lives in burrows at depths of 140–640 m (460–2,100 ft) in a variety of sediments. Although individuals can live for up to 15 years, the species shows low fecundity, where small numbers of larvae hatch at an advanced stage.
The family Polychelidae contains thirty-eight extant species of blind, benthic lobster-like crustaceans. They are found throughout the world's tropical, sub-tropical and temperate oceans, including the Mediterranean Sea and the Irish Sea.
Acanthacaris is a genus of deep-water lobsters. It contains two species, A. caeca and A. tenuimana, and is the only genus in the subfamily Neophoberinae.
Thymops birsteini, the Patagonian lobsterette, is a species of lobster found around the coasts of South America, particularly the South Atlantic. It belongs to the monotypic genus Thymops.
Galathea squamifera, the black squat lobster, or Montagu's plated lobster, is a species of squat lobster that lives in the north-east Atlantic Ocean and Mediterranean Sea.
Polychelida is an infraorder of decapod crustaceans. Fossil representatives are known dating from as far back as the Upper Triassic. A total of 38 extant species, all in the family Polychelidae, and 55 fossil species have been described.
Stereomastis sculpta is a species of "strange, blind crustacean" resembling a prawn or a squat lobster. It has a cosmopolitan distribution in deep water, being found on both sides of the Atlantic Ocean, in the Mediterranean Sea, and across much of the Indo-West Pacific, at depths of 200–4,000 metres (660–13,120 ft).
Eumunida picta is a species of squat lobster found in the deep sea. The species is strongly associated with reefs of Lophelia pertusa, a deep-water coral, and with methane seeps. It is abundant in the western Atlantic Ocean, where it is found from Massachusetts to Colombia.
Munida rugosa, commonly known as the rugose squat lobster or plated lobster, is a species of decapod crustacean found in the north east Atlantic Ocean and the Mediterranean Sea.
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.
Laurentaeglyphea neocaledonica is a species of glypheoid lobster, and the only species in the genus Laurentaeglyphea. It is known from a single specimen collected on a guyot in the Coral Sea between Australia and New Caledonia. It is thought to be an active predator with colour vision, unlike its nearest living relative, Neoglyphea inopinata.
Tricarina is an extinct genus of crustaceans in order Isopoda, known from a single incomplete fossil specimen from the Cretaceous of western Iran. It has a flattened body with three longitudinal ridges, which give it its name.
Stereomastis suhmi, the blind lobster, is a species of crustacean resembling a prawn or a squat lobster. It was first described by Charles Spence Bate in 1878.
