Lobsters

Clawed lobsters comprise a family (Nephropidae, sometimes also Homaridae) of large marine crustaceans. Lobsters are economically important as seafood, forming the basis of a global industry that nets more than US$1 billion annually.

Though several groups of crustaceans are known as "lobsters," the clawed lobsters are most often associated with the name. They are also revered for their flavor and texture. Clawed lobsters are not closely related to spiny lobsters or slipper lobsters, which have no claws (chelae), or squat lobsters. The closest relatives of clawed lobsters are the reef lobsters and the three families of freshwater crayfish.

The fossil record of clawed lobsters extends back at least to the Valanginian Age of the Cretaceous.

Evolution
Lobsters were more diverse in the Cretaceous period (53 species) than in the Tertiary (16 or 18 species), which has been postulated to have been caused by mass extinction at the K–T boundary. However, diversity rebounded in the Eocene, and it may be that the lower Tertiary diversity was mainly due to lobsters abandoning shelf depths in the late Eocene/early Oligocene, as fossils of deep-dwelling lobsters are rare. It is nevertheless clear that shelf-dwelling lobsters were more diverse during the Cretaceous.

Description
Lobsters are invertebrates, with a hard protective exoskeleton. Like most arthropods, lobsters must molt in order to grow, which leaves them vulnerable. During the molting process, several species change color. Lobsters have 10 walking legs; the front three pairs bear claws, the first of which are larger than the others. Although, like most other arthropods, lobsters are largely bilaterally symmetrical, they often possess unequal, specialized claws, like the king crab.

Lobster anatomy includes the cephalothorax which fuses the head and the thorax, both of which are covered by the chitinous carapace and the abdomen. The lobster's head bears antennae, antennules, mandibles, the first and second maxillae, and the first, second, and third maxillipeds. Because lobsters live in a murky environment at the bottom of the ocean, they mostly use their antennae as sensors. The lobster eye has a reflective structure above a convex retina. In contrast, most complex eyes use refractive ray concentrators (lenses) and a concave retina. The abdomen includes swimmerets and its tail is composed of uropods and the telson.

Lobsters, like snails and spiders, have blue blood due to the presence of haemocyanin, which contains copper. (In contrast, mammals and many other animals have red blood from iron-rich haemoglobin.) Lobsters possess a green hepatopancreas, called the tomalley by chefs, which functions as the animal's liver and pancreas.

In general, lobsters are 25 - 50 cm long and move by slowly walking on the sea floor. However, when they flee, they swim backwards quickly by curling and uncurling their abdomen. A speed of 5 m/s has been recorded. This is known as the caridoid escape reaction.

Longevity
Recent research suggests that lobsters may not slow down, weaken, or lose fertility with age. In fact, older lobsters are more fertile than younger lobsters. This longevity may be due to telomerase, an enzyme that repairs DNA sequences of the form "TTAGGG". This sequence is often referred to as the telomeres of the DNA. It has been argued that lobsters may exhibit negligible senescence and some scientists have claimed that they could effectively live indefinitely, barring injury, disease, capture, etc. ; however, this claim is highly speculative. Their undoubted longevity allows them to reach impressive sizes. According to the Guinness World Records, the largest lobster was caught in Nova Scotia, Canada, and weighed 20.15 kg.

Symbion
Animals of the genus Symbion, the only member of the animal phylum Cycliophora, live exclusively on lobster gills and mouthparts.

Ecology
Lobsters are found in all oceans. They live on rocky, sandy, or muddy bottoms from the shoreline to beyond the edge of the continental shelf. They generally live singly in crevices or in burrows under rocks.

Lobsters are omnivores, and typically eat live prey such as fish, mollusks, other crustaceans, worms, and some plant life. They scavenge if necessary, and may resort to cannibalism in captivity; however, this has not been observed in the wild. Although lobster skin has been found in lobster stomachs, this is because lobsters eat their shed skin after molting.

Gastronomy
Lobster recipes include Lobster Newberg and Lobster Thermidor. Lobster is used variously, for example in soup, bisque, lobster rolls, and cappon magro. Lobster meat may be dipped in clarified butter, resulting in a sweetened flavour.

Cooks boil live lobsters in water or steam. The lobster simmers for seven minutes for the first pound and three minutes for each additional pound.

According to the United States Food and Drug Administration (FDA), the mean level of mercury in American lobster is 0.31 ppm.

History
In North America, the American lobster did not achieve popularity until the mid-19th century, when New Yorkers and Bostonians developed a taste for it; not until the invention of a special boat, the lobster smack, did a commercial fishery flourish. Prior to this time, lobster was considered a mark of poverty or as a food for indentured servants or lower members of society in Maine, Massachusetts and the Canadian Maritimes, and servants specified in employment agreements that they would not eat lobster more than twice per week. American lobster was initially deemed worthy only of being used as fertilizer or fish bait, and it was not until well into the twentieth century that it was viewed as more than a low-priced canned staple food.

Caught lobsters are graded as new-shell, hard-shell and old-shell and, because lobsters that have recently shed their shells are the most delicate, there is an inverse relationship between the price of American lobster and its flavor. New-shell lobsters have paper-thin shells and a worse meat-to-shell ratio, but what meat exists is very sweet. However, the lobsters are so delicate that even transport to Boston almost kills them, making the market for new-shell lobsters strictly local to the fishing towns where they are offloaded. Hard-shell lobsters with firm shells but with less sweet meat can survive shipping to Boston, New York and even Los Angeles so command a higher price than new-shell lobsters. Meanwhile, old-shell lobsters, which have not shed since the previous season and have a coarser flavor, can be air-shipped anywhere in the world and arrive alive, making them the most expensive. One seafood guide notes that an eight dollar lobster dinner at a restaurant overlooking fishing piers in Maine is consistently delicious, while "the eighty-dollar lobster in a three-star Paris restaurant is apt to be as much about presentation as flavor."

Animal welfare issues
The most common way of killing a lobster is by placing it, live, in boiling water, or by splitting: severing the body in half, lengthwise. Lobsters may also be killed or rendered insensate immediately before boiling through a stab into the brain, in the belief that this will stop suffering. However, a lobster's brain operates from not one but several ganglia and disabling only the frontal ganglion does not usually result in death or unconsciousness. The boiling method is illegal in some places, such as in Reggio Emilia, Italy, where offenders face fines of up to €495.

Fishery and aquaculture
Lobsters are caught using baited, one-way traps with a color-coded marker buoy to mark cages. Lobster is fished in water between 1 and 500 fathom, although some lobsters live at 2000 fathom. Cages are of plastic-coated galvanized steel or wood. A lobster fisher may tend as many as 2,000 traps. Around the year 2000, due to overfishing and high demand, lobster aquaculture expanded. As of 2008, no lobster aquaculture operation had achieved commercial success.

Species
This list contains all extant species in the family Nephropidae:


 * Acanthacaris caeca
 * Acanthacaris tenuimana
 * Eunephrops bairdii
 * Eunephrops cadenasi
 * Eunephrops luckhursti
 * Eunephrops manningi
 * Homarinus capensis — Cape lobster
 * Homarus americanus — American lobster
 * Homarus gammarus — European lobster
 * Metanephrops andamanicus — Andaman lobster
 * Metanephrops arafurensis
 * Metanephrops armatus
 * Metanephrops australiensis — Australian scampi
 * Metanephrops binghami — Caribbean lobster
 * Metanephrops boschmai — bight lobster
 * Metanephrops challengeri — New Zealand scampi
 * Metanephrops formosanus
 * Metanephrops japonicus — Japanese lobster
 * Metanephrops mozambicus
 * Metanephrops neptunus
 * Metanephrops rubellus
 * Metanephrops sagamiensis
 * Metanephrops sibogae
 * Metanephrops sinensis — China lobster
 * Metanephrops thomsoni
 * Metanephrops velutinus
 * Nephropides caribaeus
 * Nephrops norvegicus — Norway lobster
 * Nephropsis acanthura
 * Nephropsis aculeata — Florida lobsterette
 * Nephropsis agassizii
 * Nephropsis atlantica
 * Nephropsis carpenteri
 * Nephropsis ensirostris
 * Nephropsis hamadai
 * Nephropsis holthuisii
 * Nephropsis macphersoni
 * Nephropsis malhaensis
 * Nephropsis neglecta
 * Nephropsis occidentalis
 * Nephropsis rosea
 * Nephropsis serrata
 * Nephropsis stewarti
 * Nephropsis suhmi
 * Nephropsis sulcata
 * Thymopides grobovi
 * Thymops birsteini
 * Thymopsis nilenta