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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).<ref>{{#if:97313 | {{#invoke:template wrapper|wrap|_template=cite web|_exclude=id,ID,taxon
| url = https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=97313 | title = Homarus Weber, 1795 | publisher = Integrated Taxonomic Information System }}
| Template:Citation error }}</ref> The Cape lobster, which was formerly in this genus as H. capensis, was moved in 1995 to the new genus Homarinus.<ref>Template:Cite journal</ref>
DescriptionEdit
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.<ref name="Nephropinae">Subfamily Nephropinae Dana, 1852Template:Dead linkTemplate:Cbignore, pp. 51–86 in Holthuis (1991).</ref>
While analyses of morphology suggest a close relationship between Homarinus and Homarus, molecular analyses using mitochondrial DNA reveal that they are not sister taxa.<ref name="Tshudy">Template:Cite book</ref> Both genera lack ornamentation such as spines and carinae, but are thought to have reached that state independently, through convergent evolution.<ref name="Tshudy"/> The closest living relative of Homarus is Nephrops norvegicus, while the closest relatives of Homarinus are Thymops and Thymopides.<ref name="Tshudy"/>
SpeciesEdit
Eight extinct species are known from the fossil record,<ref name="Grave">Template:Cite journal</ref> which stretches back to the Cretaceous,<ref name="Obst">Template:Cite journal</ref> 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.<ref name="Obst"/> 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.<ref>Template:Cite book In Holthuis (1991).</ref>
| Image | Scientific name | Common name | Description | Distribution | |
|---|---|---|---|---|---|
| File:Bugre europeu.jpg | Homarus gammarus Template:Small | European lobster or common lobster | may grow to a length of Template:Convert and a mass of Template:Convert, and bears a conspicuous pair of claws.<ref name="MLW_gammarus"/> In life, the lobsters are most of the time blue, only becoming "lobster red" on cooking.<ref name="Davidson">Template:Cite book</ref> Homarus gammarus is a highly esteemed food, and is widely caught using lobster pots,<ref name="MLW_gammarus"/> | Mostly around the British Isles.<ref>{{#invoke:citation/CS1|citation | CitationClass=web
}}</ref> |
| File:Bugre americanu.jpg | Homarus americanus Template:Small | Atlantic lobster, Canadian lobster, true lobster, northern lobster, Canadian Reds, or Maine lobster. | commonly ranges from Template:Convert in length and Template:Convert in weight, but have been known to reach lengths of Template:Convert<ref name="MLW_gammarus58">Template:Cite book In Holthuis (1991).</ref> and weigh as much as Template:Convert or more, making this the heaviest marine crustacean in the world.<ref name="Guinness">{{#invoke:citation/CS1|citation | CitationClass=web
}}</ref> An average adult is about Template:Convert long and weighs Template:Convert.<ref name="MLW_gammarus58"/>||Atlantic coast of North America, from Labrador in the north to Cape Hatteras, North Carolina in the south |
Fossil speciesEdit
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.<ref name="Tschudy">Template:Cite journal</ref> They are:<ref>Template:Cite book</ref><ref group="Note">Stratigraphic ranges are from Tschudy (2003)<ref name="Tschudy"/> and Polkowsky (2004).<ref>Template:Cite journal</ref></ref><ref>Template:Cite journal</ref>
- Homarus brittonestris Stenzel, 1945 – lower Turonian
- Homarus davisi Stenzel, 1945 – lower Turonian
- Homarus fami Garassino, Pasini, Nyborg, Haggart, 2021 – Albian
- Homarus lehmanni Haas, 1889 – Rupelian
- Homarus mickelsoni (Bishop, 1985) – lower Campanian
- Homarus morrisi Quayle, 1987 – Eocene
- Homarus neptunianus Polkowsky, 2004 – Oligocene
- Homarus travisensis Stenzel, 1945 – middle Albian
DistributionEdit
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,<ref name="Cobb">Template:Cite book</ref><ref name="NOBANIS">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> while H. gammarus is found from Arctic Norway to Morocco, including the British Isles and the Mediterranean Sea.<ref name="MLW_gammarus">Template:Cite book</ref><ref name="Cobb"/>
Life cycleEdit
Mating in Homarus is complex and is accompanied by a number of courtship behaviours.<ref name="Cobb"/> Males build mating shelters or burrows, and larger males can attract more females, producing a polygynous mating system.<ref name="Cobb"/> 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.<ref name="Cobb"/> 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.<ref name="Cobb"/>
The eggs generally hatch in the spring as a pre-larva, which rapidly develops into the first larval phase.<ref name="Cobb"/> This is followed by three zoeal phases, the total duration of which can vary from two weeks to two months, depending on the temperature.<ref name="Cobb"/> At the following moult, the young animal becomes a post-larva, with a gross form resembling the adult lobster.<ref name="Cobb"/> Although it can swim, using its pleopods, the post-larva soon settles to the bottom and lives as a juvenile for 3–5 years.<ref name="Cobb"/>
As adults, Homarus species moult increasingly infrequently. The size at sexual maturity varies with temperature; it is around Template:Convert for female H. americanus in southern New England, but Template:Convert around the Bay of Fundy.<ref name="Cobb"/> In H. gammarus, the size at sexual maturity is less well defined, but is in the range Template:Convert.<ref name="Cobb"/>