biology of lobsters

8/7/2019 BIOLOGY OF LOBSTERS

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BIOLOGY OF LOBSTERS

Sany Mary Benjamin

II M.Sc Zoology


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Lobsters are crustaceans and members ofthe Arthropod phylum. Crustaceans are

characterized by hard shells and jointedappendages


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SCIENTIFIC CLASSIFICATION

Kingdom:Animalia

Phylum:Arthropoda

Subphylum:Crustacea

Class:Malacostraca

Order:Decapoda

Infraorder:Astacidea

Family:Nephropidae


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Lobsters are economically importantas seafood, forming the basis of a global

industry that nets more than US $1 billionannually.

Though several groups of crustaceans areknown as "lobsters," the clawed lobsters

are most often associated with the name.

Revered for their flavor and texture.


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DISTRIBUTION

All lobsters are aquatic.

The rock lobsters and their non-clawed

relatives are marine . The clawed types, such as the Maine

lobster and scampi, live in the sea .

Yabbies and freshwater crayfish live inrivers, lakes or burrow in swampy areas.


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IMPORTANT SPECIES

The northern or East Coast lobster (Homarusamericanus)

Abundant and widespread species of the

Atlantic coast of ,North America ranging as farnorth as Labrador to as far south as Virginia.

Some animals caught in relatively deep places

on the continental slope have exceeded 3 ft (1m) in length and 44 lb (20 kg) in weight.

Probably more than 100 years old.


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The European lobster (Homarus vulgaris)is a closely related species, occurring intemperate waters of western Europ.

The Norwegian lobster or scampi(Nephrops norvegicus) is an even smallerlobster that ranges from the Norwegian

coast to the Adriatic coast in the easternMediterranean Sea.


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There are two species of spiny lobsters inNorth America. The West Coast spinylobster (Panulirus interruptus) occurs onthe Pacific coast.

The Caribbeanspiny lobster (P. argus)occurs in the Caribbean Sea, off the

Florida Coast, and in the Gulf of Mexico.

These are devoid of typical claws.


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ECOLOGY AND FISHERIES

They inhabit shallow near shore rocky orreef environments, rarely to 1000 metresdepth.

Cryptic, hiding in rock crevices during theday and coming out at night to feed

Analyses of stomach contents tell us thatthey usually feed on small invertebratesand occasionally on algae.


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Typical male lobsters will deposit packets of sperm on the undersideof the female.

External fertilization The female can store the sperm for several months, waiting for the

egg-laying season, which typically occurs during July and August.

Females breed every two years. Female lobsters carry their eggs (known as berries) beneath their

abdomen, attached to structures called spinnerets. The number of eggs is related to the size of the female, and is

typically about 5,000 eggs for a 10 in (25 cm) long female, and40,000 for a 14 in (36 cm) long animal.

One 17 in (43 cm) long female had 63,000 eggs, and anotherslightly larger one had 97,000.


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The egg masses are periodically waved on theirspinnerets to ensure their access to clean, well-oxygenated water.

Female lobsters carry their eggs for 10-11 months.

Hatchling lobsters are planktonic and commonlydisperse quite widely with water currents.

After their fifth molt, when they are about 1 in (2.5 cm)long, the young lobsters go to the bottom and begin the

relatively sedentary existence that they have for the restof their lives.


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Lobsters are extremely vulnerable to thevagaries of drift and predation when theyare in their planktonic stage, and whenthey are benthic but small. This is thereason for the enormous reproductiveoutput of these animals.


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LARVAL CYCLE

When first hatched, a lobster doesn't lookat all like an adult lobster (which may bewhy lobstermen call it a "bug").


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Feathery hairs on its legs help it swim inthe water for the first month or so.

Most lobster larva are found within the topmeter of the sea's surface.

Here the lobster will molt, or shed itsshell, three times before it begins to look

like a miniature adult.


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By that time, as a "fourth-stage" lobster, it is between 15 days and a monthold. At this stage, the lobster is a very good swimmer, although it appears tobe helplessly bobbing up and down in the water column

After the lobster settles to the bottom, it molts to the fifth stage

At this point, a small lobster still has many enemies. It spends the first yearor so in a small tunnel which it can excavate, or in a natural crevice beneathcobble or other hard bottom material.

During the first year, the lobster captures small prey which are carried inwater which the lobster pumps through its living space using its abdominalpleopods (small appendages called swimmerrets under the flexibleabdomen, which is commonly called the "tail.")

The tiny lobster spends the next few years, until almost age four, hidingunder seaweed and small rocks, catching food that drifts down to it. At thissize it may also stalk and eat little shrimp-like creatures, amphipods andisopods, called "sand fleas," even though they may be twice its size.


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DIET

Consists of crabs, clams, mussels, worms,and an occasional sea urchin or slow-witted flounder.

A lobster may eat up to 100 differentkinds of animals, and occasionally eatssome plants as well.

Captive lobsters become cannibalistic


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LOBSTER FISHING

Lobster fishing is part of thelarger fishing industry. It uses tools such asboats, navigation, and other fishing technology.

Fishing technology specific to the lobsterindustry generally includes traps, eitherrectangular-shaped or half-cylinders, once madefrom oak (coated with tar)

Now the traps are primarily made from wire

mesh covered with a thick layer of plastic toreduce oxidation of the metal. Lobster traps, or pot warp, are connected to

each other and to a buoy with rope.


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LOBSTER TRAWLER-MASSACHUSETTS


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TRADITIONAL MAINE BOAT


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LOBSTER POTS


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LOBSTER POTS

An opening permits the lobster to enter atunnel of netting.

Pots are usually constructed in two parts,called the "chamber" or kitchen, where

there is bait

The pot exits into the parlour, where it istrapped from escape.


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LOBSTER RANCHING

Lobster "ranching" would likely involve capturing pregnant females and growing theiryoung offspring in captivity, to be harvested when they reach a marketable size.

Domestication of lobsters is more complex

It involve keeping carefully selected breeding stock, and periodically spawning thesemature animals to produce progeny that could be reared under conditions optimizedfor their growth.

Controlled breeding could lead to the development of breeding stock that wasgenetically optimized for docility, growth rate, ease of spawning, resistance todisease, and other desirable traits.

Cultivation systems for lobsters are not well developed, and virtually all harvesting isdone from wild stocks of these animals.


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ECONOMIC IMPORTANCE

Lobster meat is eaten world wide

Lobster recipes include Lobster

Newberg and Lobster Thermidor. Lobster is used variously, for example in

soup, bisque, lobster rolls, and capponmagro.

Lobster meat may be dipped in clarifiedbutter, resulting in a sweetened flavour.


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The cooked lobster is called 'coral',referring to its red color when cooked.


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LOBSTER IN BUTTER SAUCE


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COOKED EUROPEAN LOBSTER


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biology of lobsters

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