Lobster

This article is about clawed lobsters. For other uses, see lobster (disambiguation).
Lobster
Temporal range: Valanginian–Recent
European lobster
(Homarus gammarus)
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Infraorder: Astacidea
Family: Nephropidae
Dana, 1852
Genera[1]
Lobsters awaiting purchase in Trenton in Hancock County, Maine

Lobsters comprise a family (Nephropidae, sometimes also Homaridae) of large marine crustaceans.

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 coastal areas they populate.[2] Commercially important species include two species of Homarus from the northern Atlantic Ocean, and scampi – the Northern Hemisphere genus Nephrops and the Southern Hemisphere genus Metanephrops. Although several other groups of crustaceans have the word "lobster" in their names, the unqualified term "lobster" generally refers to the clawed lobsters of the family Nephropidae.[3] Clawed lobsters are not closely related to spiny lobsters or slipper lobsters, which have no claws (chelae), or to squat lobsters. The closest living relatives of clawed lobsters are the reef lobsters and the three families of freshwater crayfish.

Description

Lobsters are invertebrates with a hard protective exoskeleton. Like most arthropods, lobsters must moult to grow, which leaves them vulnerable. During the moulting process, several species change colour. Lobsters have 10 walking legs; the front three pairs bear claws, the first of which are larger than the others.[4] Although lobsters are largely bilaterally symmetrical like most other arthropods, some genera possess unequal, specialised claws.

Lobster anatomy includes the cephalothorax which fuses the head and the thorax, both of which are covered by a 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 murky environments 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.[5] 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 hemocyanin which contains copper.[6] In contrast, vertebrates and many other animals have red blood from iron-rich hemoglobin. Lobsters possess a green hepatopancreas, called the tomalley by chefs, which functions as the animal's liver and pancreas.[7]

Lobsters of the family Nephropidae are similar in overall form to a number of other related groups. They differ from freshwater crayfish in lacking the joint between the last two segments of the thorax,[8] and they differ from the reef lobsters of the family Enoplometopidae in having full claws on the first three pairs of legs, rather than just one.[8] The distinctions from fossil families such as the Chilenophoberidae are based on the pattern of grooves on the carapace.[8]

Longevity

Lobsters live up to an estimated 70 years,[9] although determining age is difficult.[10] In 2012, a report was published describing how growth bands in calcified regions of the eyestalk or gastric mill in shrimps, crabs, and lobsters could be used to measure growth and mortality in decapod crustaceans.[11] Without such a technique, a lobster's age is estimated by size and other variables; this new knowledge "could help scientists better understand the population and assist regulators of the lucrative industry".[12]

Research suggests that lobsters may not slow down, weaken, or lose fertility with age, and that older lobsters may be more fertile than younger lobsters. This longevity may be due to telomerase, an enzyme that repairs long repetitive sections of DNA sequences at the ends of chromosomes, referred to as telomeres. Telomerase is expressed by most vertebrates during embryonic stages, but is generally absent from adult stages of life.[13] However, unlike most vertebrates, lobsters express telomerase as adults through most tissue, which has been suggested to be related to their longevity.[14][15][16] Lobster longevity is limited by their size. Moulting requires metabolic energy, and the larger the lobster, the more energy is needed; 10 to 15% of lobsters die of exhaustion during moulting, while in older lobsters, moulting ceases and the exoskeleton degrades or collapses entirely leading to death.[17][18]

Lobsters, like many other decapod crustaceans, grow throughout life, and are able to add new muscle cells at each moult.[19] Lobster longevity allows them to reach impressive sizes. According to Guinness World Records, the largest lobster ever caught was in Nova Scotia, Canada, weighing 20.15 kilograms (44.4 lb).[20][21]

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 are known to resort to cannibalism in captivity. However, when lobster skin is found in lobster stomachs, this is not necessarily evidence of cannibalism – lobsters eat their shed skin after moulting.[22] While cannibalism was thought to be nonexistent among wild lobster populations, it was observed in 2012 by researchers studying wild lobsters in Maine. These first known instances of lobster cannibalism in the wild are theorized to be attributed to a local population explosion among lobsters caused by the disappearance of many of the Maine lobsters' natural predators.[23]

In general, lobsters are 25–50 cm (10–20 in) long, and move by slowly walking on the sea floor. However, when they flee, they swim backward quickly by curling and uncurling their abdomens. A speed of 5 m/s (11 mph) has been recorded.[24] This is known as the caridoid escape reaction.

Symbiotic animals of the genus Symbion, the only member of the phylum Cycliophora, live exclusively on lobster gills and mouthparts.[25] Different species of Symbion have been found on the three commercially important lobsters of the North Atlantic Ocean – Nephrops norvegicus, Homarus gammarus, and Homarus americanus.[25]

As food

"Lobster claw" redirects here. For the species of flowering plants, see Lobster-claw.
Lobster served at the Fisherman's Wharf in Boston
Lobster served in Stokkseyri, Iceland

Lobster recipes include lobster Newberg and lobster Thermidor. Lobster is used in soup, bisque, lobster rolls, and cappon magro. Lobster meat may be dipped in clarified butter, resulting in a heightened flavour. Cooks boil or steam live lobsters. When a lobster is cooked, its shell's colour changes from blue to orange because the heat from cooking breaks down a protein called crustacyanin, which suppresses the orange hue of the chemical astaxanthin, which is also found in the shell.[26]

According to the United States Food and Drug Administration (FDA), the mean level of mercury in American lobster between 2005 and 2007 was 0.107 ppm.[27]

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, and commercial lobster fisheries only flourished after the development of the lobster smack,[28] a custom-made boat with open holding wells on the deck to keep the lobsters alive during transport.[29] 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.[30] Lobster was also commonly served in prisons, much to the displeasure of inmates.[31] American lobster was initially deemed worthy only of being used as fertilizer or fish bait, and until well into the 20th century, it was not viewed as more than a low-priced canned staple food.[32]

Grading

See also: Food grading

Caught lobsters are graded as new-shell, hard-shell, or old-shell, and because lobsters which have recently shed their shells are the most delicate, an inverse relationship exists between the price of American lobster and its flavour. New-shell lobsters have paper-thin shells and a worse meat-to-shell ratio, but the meat is very sweet. However, the lobsters are so delicate, 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 they command a higher price than new-shell lobsters. Meanwhile, old-shell lobsters, which have not shed since the previous season and have a coarser flavour, can be air-shipped anywhere in the world and arrive alive, making them the most expensive. One seafood guide notes that an $8 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".[32]

Welfare

Further information: Pain in crustaceans
Lobsters in a tank at a fish market

Several methods are used for killing lobsters. The most common way of killing lobsters is by placing them live in boiling water, sometimes after having been placed in a freezer for a period of time. Another method is to split the lobster or sever the body in half lengthwise. Lobsters may also be killed or rendered insensate immediately before boiling by a stab into the brain (pithing), 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.[33] The boiling method is illegal in some places, such as in Reggio Emilia, Italy, where offenders face fines up to €495.[34]

The killing methods most likely to cause pain and distress are:[33]

A device called the CrustaStun has been invented to electrocute shellfish such as lobsters, crabs, and crayfish before cooking. The device works by applying a 110-volt, 2 to 5 amp electrical charge to the animal. The CrustaStun renders the shellfish unconscious in 0.3 seconds and kills the animal in 5 to 10 seconds, compared to 3 minutes to kill a lobster by boiling.[35][36]

Fishery and aquaculture

Main article: Lobster fishing

Lobsters are caught using baited, one-way traps with a colour-coded marker buoy to mark cages. Lobster is fished in water between 2 and 900 metres (1 and 500 fathoms), although some lobsters live at 3,700 metres (2,000 fathoms). Cages are of plastic-coated galvanised steel or wood. A lobster fisher may tend as many as 2,000 traps. Around 2000, owing to overfishing and high demand, lobster aquaculture expanded.[37] As of 2008, no lobster aquaculture operation had achieved commercial success, mainly because lobsters eat each other (cannibalism) and the growth of the species is slow.[38]

Species

The fossil record of clawed lobsters extends back at least to the Valanginian age of the Cretaceous (140 million years ago).[39] This list contains all extant species in the family Nephropidae:[40]

  • Homarinus Kornfield, Williams & Steneck, 1995
  • Metanephrops andamanicus (Wood-Mason, 1892) – Andaman lobster
  • Metanephrops arafurensis (De Man, 1905)
  • Metanephrops armatus Chan & Yu, 1991
  • Metanephrops australiensis (Bruce, 1966) – Australian scampi
  • Metanephrops binghami (Boone, 1927) – Caribbean lobster
  • Metanephrops boschmai (Holthuis, 1964) – bight lobster
  • Metanephrops challengeri (Balss, 1914) – New Zealand scampi
  • Metanephrops formosanus Chan & Yu, 1987
  • Metanephrops japonicus (Tapparone-Canefri, 1873) – Japanese lobster
  • Metanephrops mozambicus Macpherson, 1990
  • Metanephrops neptunus (Bruce, 1965)
  • Metanephrops rubellus (Moreira, 1903)
  • Metanephrops sagamiensis (Parisi, 1917)
  • Metanephrops sibogae (De Man, 1916)
  • Metanephrops sinensis (Bruce, 1966) – China lobster
  • Metanephrops taiwanicus (Hu, 1983)
  • Metanephrops thomsoni (Bate, 1888)
  • Metanephrops velutinus Chan & Yu, 1991
  • Nephropsis acanthura Macpherson, 1990
  • Nephropsis aculeata Smith, 1881 – Florida lobsterette
  • Nephropsis agassizii A. Milne-Edwards, 1880
  • Nephropsis atlantica Norman, 1882
  • Nephropsis carpenteri Wood-Mason, 1885
  • Nephropsis ensirostris Alcock, 1901
  • Nephropsis holthuisii Macpherson, 1993
  • Nephropsis malhaensis Borradaile, 1910
  • Nephropsis neglecta Holthuis, 1974
  • Nephropsis occidentalis Faxon, 1893
  • Nephropsis rosea Bate, 1888
  • Nephropsis serrata Macpherson, 1993
  • Nephropsis stewarti Wood-Mason, 1872
  • Nephropsis suhmi Bate, 1888
  • Nephropsis sulcata Macpherson, 1990

See also

References

  1. ↑ Sammy De Grave; N. Dean Pentcheff; Shane T. Ahyong; et al. (2009). "A classification of living and fossil genera of decapod crustaceans" (PDF). Raffles Bulletin of Zoology. Suppl. 21: 1–109.
  2. ↑ "Homarus americanus, American lobster" (PDF). McGill University. 27 June 2007.
  3. ↑ Thomas Scott (1996). "Lobster". ABC Biologie. Walter de Gruyter. p. 703. ISBN 978-3-11-010661-9.
  4. ↑ Carlos Robles (2007). "Lobsters". In Mark W. Denny; Steven Dean Gaines. Encyclopedia of tidepools and rocky shores. University of California Press. pp. 333–335. ISBN 978-0-520-25118-2. Retrieved 2013-07-27.
  5. ↑ M. F. Land (1976). "Superposition images are formed by reflection in the eyes of some oceanic decapod Crustacea". Nature. 263 (5580): 764–765. doi:10.1038/263764a0. PMID 995187.
  6. ↑ "Copper for life – Vital copper". Association for Science Education.
  7. ↑ Shona Mcsheehy & Zoltán Mester (2004). "Arsenic speciation in marine certified reference materials". Journal of Analytical Atomic Spectrometry. 19 (3): 373–380. doi:10.1039/b314101b.
  8. 1 2 3 Dale Tshudy & Loren E. Babcock (1997). "Morphology-based phylogenetic analysis of the clawed lobsters (family Nephropidae and the new family Chilenophoberidae)". Journal of Crustacean Biology. 17 (2): 253–263. doi:10.2307/1549275. JSTOR 1549275.
  9. ↑ "Giant lobster 'aged 70' caught off Californian coast". http://www.telegraph.co.uk/. Retrieved 4 December 2014. External link in |website= (help)
  10. ↑ T. Wolff (1978). "Maximum size of lobsters (Homarus) (Decapoda, Nephropidae)". Crustaceana. 34: 1–14. doi:10.1163/156854078X00510.
  11. ↑ Kilada, Raouf; Bernard Sainte-Marie; Rémy Rochette; Neill Davis; Caroline Vanier; Steven Campana. "Direct determination of age in shrimps, crabs, and lobsters". Canadian Journal of Fisheries and Aquatic Sciences. NRC Research Press, a division of Canadian Science Publishing. Retrieved 22 December 2014.
  12. ↑ Canfield, Clarke (30 November 2012). "Lobster age shown by counting its rings like a tree, study reveals". The Huffington Post. TheHuffingtonPost.com, Inc. Retrieved 22 December 2014.
  13. ↑ Cong YS (2002). "Human Telomerase and Its Regulation". Microbiology and Molecular Biology Reviews. 66 (3): 407–425. doi:10.1128/MMBR.66.3.407-425.2002. PMC 120798Freely accessible. PMID 12208997.
  14. ↑ Wolfram Klapper, Karen Kühne, Kumud K. Singh, Klaus Heidorn, Reza Parwaresch & Guido Krupp (1998). "Longevity of lobsters is linked to ubiquitous telomerase expression". FEBS Letters. 439 (1–2): 143–146. doi:10.1016/S0014-5793(98)01357-X.
  15. ↑ Jacob Silverman. "Is there a 400 pound lobster out there?". howstuffworks.
  16. ↑ David Foster Wallace (2005). "Consider the Lobster". Consider the Lobster and Other Essays. Little, Brown & Company. ISBN 0-316-15611-6.
  17. ↑ Koren, Marina (June 3, 2013). "Don't Listen to the Buzz: Lobsters Aren't Actually Immortal". Smithsonian.
  18. ↑ http://www.lobsters.org/tlcbio/biology3.html
  19. ↑ C. K. Govind (1995). "Muscles and their innervation". In Jan Robert Factor. Biology of the Lobster Homarus americanus. San Diego, CA: Academic Press. pp. 291–312. ISBN 978-0-12-247570-2.
  20. ↑ "Heaviest marine crustacean". Guinness World Records. Archived from the original on May 28, 2006. Retrieved August 3, 2006.
  21. ↑ "Giant lobster landed by boy, 16". BBC News. June 26, 2006.
  22. ↑ "Homarus americanus, Atlantic lobster". MarineBio.org. Retrieved December 27, 2006.
  23. ↑ Jason McLure (December 3, 2012). "Cruel new fact of crustacean life: lobster cannibalism". Reuters. Retrieved December 5, 2012.
  24. ↑ "The American lobster – frequently asked questions". St. Lawrence Observatory, Fisheries and Oceans Canada. October 19, 2005. Archived from the original on March 10, 2010.
  25. 1 2 M. Obst, P. Funch & G. Giribet (2005). "Hidden diversity and host specificity in cycliophorans: a phylogeographic analysis along the North Atlantic and Mediterranean Sea". Molecular Ecology. 14 (14): 4427–4440. doi:10.1111/j.1365-294X.2005.02752.x. PMID 16313603.
  26. ↑ http://www.howitworksdaily.com
  27. ↑ "Mercury Levels in Commercial Fish and Shellfish". Food and Drug Administration. Retrieved 20 November 2015.
  28. ↑ Colin Woodard (2004). The Lobster Coast. New York: Viking/Penguin. pp. 170–180. ISBN 0-670-03324-3.
  29. ↑ "The Lobster Institute: History". The Lobster Institute at the University of Maine. Retrieved 2012-06-11.
  30. ↑ Mark Henderson (October 24, 2005). "How lobster went up in the world". London: The Times. Retrieved May 11, 2010.
  31. ↑ "Lobster". All About Maine. Secretary of State of Maine. Retrieved July 29, 2013.
  32. 1 2 Johnson, Paul (2007). "Lobster". Fish Forever: The Definitive Guide to Understanding, Selecting, and Preparing Healthy, Delicious, and Environmentally Sustainable Seafood. John Wiley & Sons. pp. 163–175. ISBN 978-0-7645-8779-5.
  33. 1 2 Yue, S. (2008). "The welfare of crustaceans at slaughter". Humane Society of the United States.
  34. ↑ Bruce Johnston (March 6, 2004). "Italian animal rights law puts lobster off the menu". London: The Daily Telegraph.
  35. ↑ McSmith, A. (2009). "I'll have my lobster electrocuted, please". The Independent (Newspaper). Retrieved June 14, 2013.
  36. ↑ Anon. (2010). "CrustaStun: The 'humane' gadget that kills lobsters with a single jolt of electricity". MailOnline (Newspaper). Retrieved June 14, 2013.
  37. ↑ Asbjørn Drengstig, Tormod Drengstig & Tore S. Kristiansen. "Recent development on lobster farming in Norway – prospects and possibilities". UWPhoto ANS.
  38. ↑ "Riddles, Trivia and More". Gulf of Maine Research Institute. February 24, 2012. Retrieved July 23, 2012.
  39. ↑ Dale Tshudy, W. Steven Donaldson, Christopher Collom, Rodney M. Feldmann & Carrie E. Schweitzer (2005). "Hoploparia albertaensis, a new species of clawed lobster (Nephropidae) from the Late Coniacean, shallow-marine Bad Heart Formation of northwestern Alberta, Canada". Journal of Paleontology. 79 (5): 961–968. doi:10.1666/0022-3360(2005)079[0961:HAANSO]2.0.CO;2.
  40. ↑ Tin-Yam Chan (2010). "Annotated checklist of the world's marine lobsters (Crustacea: Decapoda: Astacidea, Glypheidea, Achelata, Polychelida)" (PDF). The Raffles Bulletin of Zoology. Suppl. 23: 153–181.

Further reading

External links

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