Lobsters are invertebrates, members of the Class Crustacea of
the Phylum Arthropoda. This class includes animals without backbones and
with hard shells like crab, shrimp, crayfish, water fleas and wood lice.
A male lobster is called a cock and a female a hen or
chicken (when she weighs about 1 pound).
There are two kinds of lobsters, the "true" lobster
(also called American lobster) and the spiny lobster. The true lobster
has claws on the first four legs, lacking in the spiny lobster. The
spiny lobster has a pair of horns above the eyes, lacking in the true
lobster. Spiny lobsters also have two large cream-colored spots on the
top of the second segment of the tail.
Small lobsters, less than 1.5 inches carapace (carapace
length is measured from the rear of the eye socket to the rear of the
main body shell), hide in and about sea weeds and rocky habitat that
provide enough food and shelter from predators. Adolescent lobsters, 1.5
to 3.5 inches carapace, are found in coastal habitats and offshore
areas. Adult lobsters inhabit deeper waters, but return seasonally to
shallow warmer waters. Spiny lobsters inhabit tropical and subtropical
waters of the Atlantic Ocean, Caribbean Sea and Gulf of Mexico.
Lobster can have many different colors, including
blue-green, blue, red, yellow, red-orange and white. Some lobsters come
in two colors, having half of their shell one color and the other half
Lobsters grow by molting, or shedding their shells. Before
they shed the old shell, they will form a thin one underneath. When molting,
they secrete enzymes that soften the shell and connective joints. The
lobster will then struggle out of its old shell while simultaneously
absorbing water which expands their body size. This process takes about 15
minutes. Each time they molt, they will increase their size about 20%.
After molting, lobsters will eat voraciously. They often
eat their old shell which will replenish the lost calcium and speed up
the hardening of the new shell. It takes about 6 to 8 weeks before their
new shell is hard enough for lobsters to be able to protect themselves
against their natural enemies. While they are soft and fragile, lobsters
will bury themselves in the mud or hide under rocks.
A young, immature lobster (first 5-7 years) will molt
about 25 times a year. An adult male lobster molts twice a year and an
adult female lobster once a year, usually in the summer. When lobsters
get older, they will molt only once every 3-4 years.
The only way to gauge the exact age of a lobster would
be by their shell. However, since lobsters shed their shells so often,
it is impossible to determine their age. Knowledge of body size at age
makes scientists believe that lobsters can attain a maximum age of 100
years. The normal life span is about 15 years. Lobsters can grow to be 3
feet long in overall body length.
To determine the gender of a lobster, you have to look
at the swimmerets, the small feathery appendages on the underside of the
tail. The first pair of swimmerets closest to the body are hard and bony
on a male and soft and feathery on a female. Only the female has a small
shield between the second pair of walking legs, which is the sperm
receptacle where she stores the sperm after mating until she lays her
eggs. The female also has a wider tail, needed to be able to carry all
Female lobsters mate primarily when they are in the
soft-shell state, right after molting. They can carry live sperm for up to
two years until they decide to fertilize their eggs. A 1 pound female will
carry about 8,000 eggs. A 9 pound female may carry more than 100,000 eggs.
Freshly laid eggs are the size of the head of a pin and are attached to the
swimmerets under their mothers tail for almost a year with a glue-like
substance. During that year the larvae will molt about six times while still
in the egg.
When the eggs are ready to hatch, the mother will shake
them out of their shell, releasing them as larvae. The larvae will float
to the surface for 4 to 6 weeks. At the surface, they are easy prey for
sea birds, fish and other enemies. Less than 0.1% of the larvae will
survive, settle to the bottom and develop as baby lobsters.
Like dolphins, lobsters use complicated signals to
establish social relationships. They sometimes walk hand-in-hand, the
old leading the young.
Lobsters usually hunt for food at night. They eat fish,
crabs, clams, snails, sea stars, mussels and sea urchins. By nature,
lobsters are not cannibalistic, except when held in crowded conditions.
Lobsters chew their food in their stomach, which is very
close to their mouth, between three grinding surfaces that look like
molar teeth called the "gastric mill".
To escape from enemies, lobsters swim backwards by
flipping their tail.
The lobster's body has 19 parts, each covered by a section of
the shell. The shell is thin and soft where the parts join, so
lobsters can bend their body and move about.
Lobsters breathe through gills located beneath the shell on both
sides of their thorax (center part).
Lobsters eyes are compound eyes, consisting of hundreds of
lenses joined together on the ends of pair of jointed organs called
stalks. The four small antennae on the front of their heads are used
to "smell" their food or chemicals in the water. The tiny
sensory hairs along their legs are used to "taste" their
food. Lobsters keep their antennae and eye stalks moving constantly to
search for food and to watch for enemies.
True lobsters have two very powerful claws. One claw is sharp
and used for cutting, the other is bony and used for crushing.
Lobsters that have their heavy ("crusher") claw on the right
are considered "right-handed" and the others are
"left-handed". Some lobsters are ambidextrous, they usually
favor the claw that is the largest.
Lobsters can lose claws, legs, eyes and antennae through
accident or self-defense, but are able to regenerate them. Lobsters
often fight with other lobsters for territory. If another lobster
seizes their claw, they may drop their claw to escape. Sometimes, the
more aggressive lobster will tear the claw of the opponent off. A
lobster with a claw missing is called a cull It takes about 3 to 4
molt cycles for the claw to grow back to full size.
Lobsters have a sophisticated nervous system that allows it to
sense actions that will cause it harm and feel pain. Lobsters don't
have an autonomic nervous system that puts it into a state of shock
when it is harmed. For this reason, they will feel pain until their
nervous system is completely destroyed.