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Lobster

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Title: Lobster  
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Subject: Acanthacaris, Dinochelus, Eunephrops, Thymopides, Nephropsis
Collection: Commercial Crustaceans, Edible Crustaceans, Negligibly Senescent Organisms, Seafood, True Lobsters, Valanginian First Appearances
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Lobster

Lobster
Temporal range: Valanginian–Recent
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Homarus gammarus, European lobster
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Infraorder: Astacidea
Family: Nephropidae
Dana, 1852
Genera[1]
Lobster x-ray
Lobster x-ray
Lobsters awaiting purchase in Trenton in Hancock County, Maine

Clawed lobsters comprise a chelae), or to squat lobsters. The closest living relatives of clawed lobsters are the reef lobsters and the three families of freshwater crayfish.

Contents

  • Description 1
  • Longevity 2
  • Ecology 3
  • As food 4
    • History 4.1
    • Grading 4.2
  • Welfare 5
  • Fishery and aquaculture 6
  • Species 7
  • See also 8
  • References 9
  • Further reading 10
  • External links 11

Description

Lobsters are invertebrates with a hard protective exoskeleton. Like most arthropods, lobsters must moult in order 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, like most other arthropods, lobsters are largely bilaterally symmetrical, 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 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.[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 haemocyanin which contains copper.[6] In contrast, vertebrates 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.[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 Chilenophoberidae are based on the pattern of grooves on the carapace.[8]

Longevity

Large lobsters are estimated to have aged up to 70 years old,[9] although determining age is difficult.[10]

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 chromsomes, referred to as telomeres. Telomerase is expressed by most vertebrates during embryonic stages but is generally absent from adult stages of life.[11] However, unlike most vertebrates, lobsters express telomerase as adults through most tissue, which has been suggested to be related to their longevity.[12][13][14]

Lobsters, like many other decapod crustaceans, grow throughout life, and are able to add new muscle cells at each molt.[15] 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).[16][17]

Ecology

Lobsters are found in all oceans and found on land. 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.[18] While cannibalism was thought to be nonexistent among wild lobster populations, it was observed in 2012 by researchers studying wild lobsters in Maine, where it is theorized that these first known instances of lobster cannibalism in the wild can be attributed to a local population explosion among lobsters caused by the disappearance of many of the Maine lobsters' natural predators.[19]

In general, lobsters are 25–50 centimetres (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 abdomen. A speed of 5 metres per second (11 mph) has been recorded.[20] 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.[21] 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.[21]

As food

American lobster, cooked
Steamed whole lobster, with claws cracked and tail split
Nutritional value per 100 g (3.5 oz)
Energy 372 kJ (89 kcal)
0 g
Sugars 0 g
Dietary fibre 0 g
Fat
0.86 g
Saturated 0.208 g
Monounsaturated 0.253 g
Polyunsaturated 0.340 g
19.0 g
Vitamins
Thiamine (B1)
(2%)
0.023 mg
Riboflavin (B2)
(1%)
0.017 mg
Niacin (B3)
(12%)
1.830 mg
(33%)
1.667 mg
Vitamin B6
(9%)
0.119 mg
Folate (B9)
(3%)
11 μg
Vitamin C
(0%)
0 mg
Trace metals
Calcium
(10%)
96 mg
Iron
(2%)
0.29 mg
Magnesium
(12%)
43 mg
Phosphorus
(26%)
185 mg
Potassium
(5%)
230 mg
Zinc
(43%)
4.05 mg
Percentages are roughly approximated using US recommendations for adults.

Cooks boil or steam live lobsters. The lobster cooks for seven minutes for the first pound and three minutes for each additional pound.[22]

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 sweetened flavour.

According to the United States Food and Drug Administration (FDA), the mean level of mercury in American lobster is 0.31 ppm.[23]

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,[24] a custom-made boat with open holding wells on the deck to keep the lobsters alive during transport.[25] 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.[26] Lobster was also commonly served in prisons, much to the displeasure of inmates.[27] 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.[28]

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, there is an inverse relationship 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 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 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 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".[28]

Welfare

The most common way of killing a lobster is by placing it 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 or unconsciousness.[14] The boiling method is illegal in some places, such as in Reggio Emilia, Italy, where offenders face fines of up to 495.[29]

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, 2–5 amp electrical charge to the animal. It is reported 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.[30][31]

Fishery and aquaculture

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 the year 2000, owing to overfishing and high demand, lobster aquaculture expanded.[32] 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.[33]

Species

The fossil record of clawed lobsters extends back at least to the Valanginian Age of the Cretaceous (140 million years ago).[34] This list contains all extant species in the family Nephropidae:[35]

  • Homarinus Kornfield, Williams & Steneck, 1995

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" ( 
  2. ^ , American lobster"Homarus americanus" ( 
  3. ^ Thomas Scott (1996). "Lobster". ABC Biologie.  
  4. ^ Carlos Robles (2007). "Lobsters". In Mark W. Denny & Steven Dean Gaines. Encyclopedia of tidepools and rocky shores.  
  5. ^ M. F. Land (1976). "Superposition images are formed by reflection in the eyes of some oceanic decapod Crustacea".  
  6. ^ "Copper for life – Vital copper".  
  7. ^ Shona Mcsheehy & Zoltán Mester (2004). "Arsenic speciation in marine certified reference materials".  
  8. ^ a b c Dale Tshudy & Loren E. Babcock (1997). "Morphology-based phylogenetic analysis of the clawed lobsters (family Nephropidae and the new family Chilenophoberidae)".  
  9. ^ "Giant lobster 'aged 70' caught off Californian coast". http://www.telegraph.co.uk/. Retrieved 4 December 2014. 
  10. ^ T. Wolff (1978). "Maximum size of lobsters (Homarus) (Decapoda, Nephropidae)".  
  11. ^ Cong YS (2002). "Human Telomerase and It's Regulation". Microbiology and Molecular Biology Reviews 66 (3): 407–425.  
  12. ^ Wolfram Klapper, Karen Kühne, Kumud K. Singh, Klaus Heidorn, Reza Parwaresch & Guido Krupp (1998). "Longevity of lobsters is linked to ubiquitous telomerase expression".  
  13. ^ Jacob Silverman. "Is there a 400 pound lobster out there?".  
  14. ^ a b  
  15. ^ C. K. Govind (1995). "Muscles and their innervation". In Jan Robert Factor. Biology of the Lobster Homarus americanus. San Diego, CA:  
  16. ^ "Heaviest marine crustacean".  
  17. ^ "Giant lobster landed by boy, 16".  
  18. ^ , Atlantic lobster"Homarus americanus". MarineBio.org. Retrieved December 27, 2006. 
  19. ^ Jason McLure (December 3, 2012). "Cruel new fact of crustacean life: lobster cannibalism".  
  20. ^ "The American lobster – frequently asked questions". St. Lawrence Observatory,  
  21. ^ a b M. Obst, P. Funch & G. Giribet (2005). "Hidden diversity and host specificity in cycliophorans: a phylogeographic analysis along the North Atlantic and Mediterranean Sea".  
  22. ^ "Cooking lobsters". Atwood Lobster Company. Archived from the original on June 7, 2007. Retrieved June 30, 2007. 
  23. ^ "Mercury Levels in Commercial Fish and Shellfish".  
  24. ^ Colin Woodard (2004). The Lobster Coast. New York: Viking/Penguin. pp. 170–180.  
  25. ^ "The Lobster Institute: History". The Lobster Institute at the University of Maine. Retrieved 2012-06-11. 
  26. ^ Mark Henderson (October 24, 2005). "How lobster went up in the world". London: The Times. Retrieved May 11, 2010. 
  27. ^ "Lobster". All About Maine.  
  28. ^ a b Johnson, Paul (2007). "Lobster". Fish Forever: The Definitive Guide to Understanding, Selecting, and Preparing Healthy, Delicious, and Environmentally Sustainable Seafood.  
  29. ^ Bruce Johnston (March 6, 2004). "Italian animal rights law puts lobster off the menu". London:  
  30. ^ McSmith, A. (2009). "I'll have my lobster electrocuted, please". The Independent (Newspaper). Retrieved June 14, 2013. 
  31. ^ Anon. (2010). "CrustaStun: The 'humane' gadget that kills lobsters with a single jolt of electricity". MailOnline (Newspaper). Retrieved June 14, 2013. 
  32. ^ Asbjørn Drengstig, Tormod Drengstig & Tore S. Kristiansen. "Recent development on lobster farming in Norway – prospects and possibilities". UWPhoto ANS. 
  33. ^ "Riddles, Trivia and More".  
  34. ^ 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".  
  35. ^ Tin-Yam Chan (2010). "Annotated checklist of the world's marine lobsters (Crustacea: Decapoda: Astacidea, Glypheidea, Achelata, Polychelida)" ( 

Further reading

  • Corson, Trevor (2005). The Secret Life of Lobsters: How Fishermen and Scientists Are Unraveling the Mysteries of Our Favorite Crustacean (1st Harper Perennial ed.). New York: HarperCollins.  
  • Bruce F. Phillips, ed. (2006). Lobsters: Biology, Management, Aquaculture and Fisheries. Wiley.  
  • Townsend, Elisabeth (2012). Lobster: A Global History. London: Reaktion Books.  

External links

  •  
  • Atlantic Veterinary College Lobster Science Centre
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