The American lobster (Homarus americanus) 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.
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NocturnalNocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal",...
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ScavengerScavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While sc...
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MolluscivoreA molluscivore is a carnivorous animal that specializes in feeding on molluscs such as gastropods, bivalves, brachiopods, and cephalopods. Known mo...
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OmnivoreAn omnivore is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and ani...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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PiscivoresA piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withHomarus americanus commonly reaches 200–610 millimetres (8–24 in) long and weighs 0.45–4.08 kilograms (1–9 lb) in weight, but has been known to weigh as much as 20 kg (44 lb), making this the heaviest crustacean in the world. Together with Sagmariasus verreauxi, it is also the longest decapod crustacean in the world; an average adult is about 230 mm (9 in) long and weighs 680 to 910 g (1.5 to 2 lb). The longest American lobsters have a body (excluding claws) 64 cm (25 in) long. According to Guinness World Records, the heaviest crustacean ever recorded was an American lobster caught off Nova Scotia, Canada, weighing 20.1 kg (44.4 lb).
The closest relative of H. americanus is the European lobster, Homarus gammarus. The two species are very similar, and can be crossed artificially, although hybrids are unlikely to occur in the wild since their ranges do not overlap. The two species can be distinguished by several characteristics:
The normal coloration of Homarus americanus is bluish green to brown with red spines due to a mixture of yellow, blue, and red pigments that occur naturally in the shell. On rare occasions these colors are distorted due to genetic mutations or conditions creating a spectacle for those who catch them. In 2012 it was reported that there has been an increase in these "rare" catches due to unclear reasons. Social media influence making reporting and sharing more accessible to a drop in predator populations have been suggested as possible reasons. The lobsters mentioned below thus usually receive media coverage due to their rarity and eye appeal.
Homarus americanus is distributed along the Atlantic coast of North America, from Labrador in the north to Cape Hatteras, North Carolina, in the south. South of New Jersey, the species is uncommon, and landings in Delaware, Maryland, Virginia and North Carolina usually make up less than 0.1% of all landings. A fossil claw assigned to Homarus americanus was found at Nantucket, dating from the Pleistocene. In 2013, an American lobster was caught at the Farallon Islands off the coast of California. It has been introduced to Norway and potentially Iceland.
The American lobster thrives in cold, shallow waters where there are many rocks and other places to hide from predators. It typically lives at a depth of 4–50 m (13–164 ft), but can be found up to 480 m (1,570 ft) below the surface.
The natural diet of H. americanus is relatively consistent across different habitats. It is dominated by mollusks (especially mussels, clams and snails), echinoderms and polychaetes, although a wide range of other prey items may be eaten, including other crustaceans (such as crabs), brittle stars, cnidarians and small fish. It will also feed on dead animals, as well as algae and eelgrass. Since lobsters sometimes eat their own molted shell, they were thought to be cannabalistic, but this has never been recorded in the wild. Lobsters in Maine have been shown to gain 35–55% of their calories from herring, which is used as bait for lobster traps. Only 6% of lobsters entering lobster traps to feed are caught.
Mating only takes place shortly after the female has molted and her exoskeleton is still soft. The female releases a pheromone which causes the males to become less aggressive and to begin courtship, which involves a courtship dance with claws closed. Eventually, the male inserts spermatophores (sperm packets) into the female's seminal receptacle using his first pleopods; the female may store the sperm for up to 15 months.
The female releases eggs through her oviducts, and they pass the seminal receptacle and are fertilized by the stored sperm. They are then attached to the female's pleopods (swimmerets) using an adhesive, where they are cared for until they are ready to hatch. The female cleans the eggs regularly and fans them with water to keep them oxygenated. The large telolecithal eggs may resemble the segments of a raspberry, and a female carrying eggs is said to be "in berry". Since this period lasts 10–11 months, berried females can be found at any time of year. In the waters off New England, the eggs are typically laid in July or August, and hatch the following May or June. The developing embryo passes through several molts within the egg, before hatching as a metanauplius larva. When the eggs hatch, the female releases them by waving her tail in the water, setting batches of larvae free.
The metanauplius of H. americanus is.mw-parser-output.frac{white-space:nowrap}.mw-parser-output.frac.num,.mw-parser-output.frac.den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output.frac.den{vertical-align:sub}.mw-parser-output.sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}8.5 mm (1⁄3 in) long, transparent, with large eyes and a long spine projecting from its head. It quickly molts, and the next three stages are similar, but larger. These molts take 10–20 days, during which the planktonic larvae are vulnerable to predation; only 1 in 1,000 is thought to survive to the juvenile stage. To reach the fourth stage – the post-larva – the larva undergoes metamorphosis, and subsequently shows a much greater resemblance to the adult lobster, is around 13 mm (1⁄2 in) long, and swims with its pleopods. At this stage, the lobster's claws are still relatively small so they rely primarily on tail-flip escapes if threatened.
After the next molt, the lobster sinks to the ocean floor and adopts a benthic lifestyle. It molts more and more infrequently, from an initial rate of ten times per year to once every few years. After one year it is around 25–38 mm (1–1.5 in) long, and after six years it may weigh 0.45 kilograms (1 lb). By the time it reaches the minimum landing size, an individual may have molted 25–27 times, and thereafter each molt may signal a 40%–50% increase in weight, and a 14% increase in carapace length. If threatened, adult lobsters will generally choose to fight unless they have lost their claws.
