Homarus Temporal range: | |
---|---|
Homarus gammarus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Malacostraca |
Order: | Decapoda |
Suborder: | Pleocyemata |
Family: | Nephropidae |
Genus: | Homarus Weber, 1795 |
Type species | |
Astacus marinus Fabricius, 1775 | |
Extant species | |
H. americanus – American lobster Contents |
Homarus is a genus of lobsters, which include the common and commercially significant species Homarus americanus (the American lobster) and Homarus gammarus (the European lobster). [1] The Cape lobster, which was formerly in this genus as H. capensis, was moved in 1995 to the new genus Homarinus. [2]
Homarus is one of three extant genera of clawed lobsters to show dimorphism between claws – a specialisation into a crushing claw and a cutting claw. The other similar genera are Nephrops , which is much more slender, and has grooves along the claws and the abdomen, and Homarinus , the Cape lobster from South Africa, which is even smaller, and has hairy claws. [3]
While analyses of morphology suggest a close relationship between Homarinus and Homarus, molecular analyses using mitochondrial DNA reveal that they are not sister taxa. [4] Both genera lack ornamentation such as spines and carinae, but are thought to have reached that state independently, through convergent evolution. [4] The closest living relative of Homarus is Nephrops norvegicus , while the closest relatives of Homarinus are Thymops and Thymopides . [4]
Eight extinct species are known from the fossil record, [5] which stretches back to the Cretaceous, [6] but only two species survive. These two species, the American lobster and the European lobster, are very similar and may have speciated as recently as the Pleistocene, during climatic fluctuations. [6] The best characters for distinguishing them are the geographic distribution, with the American lobster in the western Atlantic and the European lobster in the eastern Atlantic, and by the presence of one or more teeth on the underside of the rostrum in H. americanus but not in H. gammarus. [7]
Image | Scientific name | Common name | Description | Distribution |
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Homarus gammarus Linnaeus, 1758 | European lobster or common lobster | may grow to a length of 60 cm (24 in) and a mass of 6 kilograms (13 lb), and bears a conspicuous pair of claws. [8] In life, the lobsters are most of the time blue, only becoming "lobster red" on cooking. [9] Homarus gammarus is a highly esteemed food, and is widely caught using lobster pots, [8] | Mostly around the British Isles. [10] | |
Homarus americanus H. Milne-Edwards, 1837 | Atlantic lobster, Canadian lobster, true lobster, northern lobster, Canadian Reds, or Maine lobster. | commonly ranges from 20–60 cm (8–24 in) in length and 0.5–4.1 kg (1.1–9.0 lb) in weight, but have been known to reach lengths of 64 cm (25 in) [11] and weigh as much as 20 kg (44 lb) or more, making this the heaviest marine crustacean in the world. [12] An average adult is about 23 cm (9 in) long and weighs 700–900 g (25–32 oz). [11] | Atlantic coast of North America, from Labrador in the north to Cape Hatteras, North Carolina in the south | |
The boundaries between Homarus and the extinct genus Hoploparia are unclear, and some species, such as Hoploparia benedeni have been transferred between the two genera. Eight species have been assigned to Homarus from the fossil record. [13] They are: [14] [Note 1] [16]
The two extant species of Homarus are both found in the North Atlantic Ocean. H. americanus is found from Labrador to North Carolina in the western North Atlantic, [17] [18] while H. gammarus is found from Arctic Norway to Morocco, including the British Isles and the Mediterranean Sea. [8] [17]
Mating in Homarus is complex and is accompanied by a number of courtship behaviours. [17] Males build mating shelters or burrows, and larger males can attract more females, producing a polygynous mating system. [17] A few days before moulting, a female will choose a mate, and will remain in his shelter until the moult. The male will then insert a spermatophore into the female's seminal vesicle, where it may be stored for several years. [17] The eggs of Homarus species are laid in the autumn, being fertilised externally as they exit, and are carried by the female on her pleopods. [17]
The eggs generally hatch in the spring as a pre-larva, which rapidly develops into the first larval phase. [17] This is followed by three zoeal phases, the total duration of which can vary from two weeks to two months, depending on the temperature. [17] At the following moult, the young animal becomes a post-larva, with a gross form resembling the adult lobster. [17] Although it can swim, using its pleopods, the post-larva soon settles to the bottom and lives as a juvenile for 3–5 years. [17]
As adults, Homarus species moult increasingly infrequently. The size at sexual maturity varies with temperature; it is around 70 mm (2.8 in) for female H. americanus in southern New England, but 100 mm (3.9 in) around the Bay of Fundy. [17] In H. gammarus, the size at sexual maturity is less well defined, but is in the range 80–140 mm (3.1–5.5 in). [17]
Lobsters are malacostracans of the family Nephropidae or its synonym Homaridae. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, which are usually much larger than the others. Highly prized as seafood, lobsters are economically important and are often one of the most profitable commodities in the coastal areas they populate.
The Caridea, commonly known as caridean shrimp or true shrimp, from the Greek word καρίς, καρίδος, are an infraorder of shrimp within the order Decapoda. This infraorder contains all species of true shrimp. They are found widely around the world in both fresh and salt water. Many other animals with similar names – such as the mud shrimp of Axiidea and the boxer shrimp of Stenopodidea – are not true shrimp, but many have evolved features similar to true shrimp.
The American lobster is a species of lobster found on the Atlantic coast of North America, chiefly from Labrador to New Jersey. It is also known as Atlantic lobster, Canadian lobster, true lobster, northern lobster, Canadian Reds, or Maine lobster. It can reach a body length of 64 cm (25 in), and a mass of over 20 kilograms (44 lb), making it not only the heaviest crustacean in the world, but also the heaviest of all living arthropod species. Its closest relative is the European lobster Homarus gammarus, which can be distinguished by its coloration and the lack of spines on the underside of the rostrum. American lobsters are usually bluish green to brown with red spines, but several color variations have been observed.
Homarus gammarus, known as the European lobster or common lobster, is a species of clawed lobster from the eastern Atlantic Ocean, Mediterranean Sea and parts of the Black Sea. It is closely related to the American lobster, H. americanus. It may grow to a length of 60 cm (24 in) and a mass of 6 kilograms (13 lb), and bears a conspicuous pair of claws. In life, the lobsters are blue, only becoming "lobster red" on cooking. Mating occurs in the summer, producing eggs which are carried by the females for up to a year before hatching into planktonic larvae. Homarus gammarus is a highly esteemed food, and is widely caught using lobster pots, mostly around the British Isles.
Lobsters are widely fished around the world for their meat. They are often hard to catch in large numbers, but their large size can make them a profitable catch. Although the majority of the targeted species are tropical, the majority of the global catch is in temperate waters.
Nephrops norvegicus, known variously as the Norway lobster, Dublin Bay prawn, langoustine or scampi, is a slim, coral colored lobster that grows up to 25 cm (10 in) long, and is "the most important commercial crustacean in Europe". It is now the only extant species in the genus Nephrops, after several other species were moved to the closely related genus Metanephrops. It lives in the north-eastern Atlantic Ocean, and parts of the Mediterranean Sea, but is absent from the Baltic Sea and Black Sea. Adults emerge from their burrows at night to feed on worms and fish.
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.
Astacidea is an infraorder of decapod crustaceans including lobsters, crayfish, and their close relatives.
The Cape lobster, Homarinus capensis, is a species of small lobster that lives off the coast of South Africa, from Dassen Island to Haga Haga. Only a few dozen specimens are known, mostly regurgitated by reef-dwelling fish. It lives in rocky reefs, and is thought to lay large eggs that have a short larval phase, or that hatch directly as a juvenile. The species grows to a total length of 10 cm (3.9 in), and resembles a small European or American lobster; it was previously included in the same genus, Homarus, although it is not very closely related to those species, and is now considered to form a separate, monotypic genus – Homarinus. Its closest relatives are the genera Thymops and Thymopides.
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.
Metanephrops is a genus of lobsters, commonly known as scampi. Important species for fishery include Metanephrops australiensis and Metanephrops challengeri. It differs from other lobsters such as Homarus and Nephrops norvegicus in that its two main claws are of equal size, rather than being differentiated into a crusher and a pincher. There are 18 extant species recognised in the genus:
Scyllarides latus, the Mediterranean slipper lobster, is a species of slipper lobster found in the Mediterranean Sea and in the eastern Atlantic Ocean. It is edible and highly regarded as food, but is now rare over much of its range due to overfishing. Adults may grow to 1 foot (30 cm) long, are camouflaged, and have no claws. They are nocturnal, emerging from caves and other shelters during the night to feed on molluscs. As well as being eaten by humans, S. latus is also preyed upon by a variety of bony fish. Its closest relative is S. herklotsii, which occurs off the Atlantic coast of West Africa; other species of Scyllarides occur in the western Atlantic Ocean and the Indo-Pacific. The larvae and young animals are largely unknown.
Scyllarides is a genus of slipper lobsters.
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults, more-so than where the larvae are planktonic, and thereby easily caught.
Nephropsis atlantica, sometimes called the scarlet lobsterette or scarlet clawed lobster, is a species of lobster from the Atlantic Ocean.
Thymopides is a genus of deep-water lobsters, comprising the two species Thymopides grobovi and Thymopides laurentae.
Hoploparia is a genus of fossil lobster belonging to the family Nephropidae. The type species of this genus is Hoploparia longimana.
Notahomarus is a genus of fossil lobster belonging to the family Nephropidae that is known from fossils found only in Lebanon. The type species, N. hakelensis, was initially placed within the genus Homarus in 1878, but it was transferred to the genus Notahomarus in 2017.
Tillocheles is an extinct genus of decapod crustaceans that lived during the Cretaceous period. Two species are currently placed in the genus. Fossils of the earlier type species, T. shannonae, have been found in Queensland, while remains of the later species, T. kaoriae, are known from Hokkaido.
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