Lobster is the name of a number of animals that live on the bottom of the ocean. They are crustaceans, hard-shelled animals with segmented bodies and jointed legs. People around the world prize lobsters for their tasty white meat. Great quantities of these animals are harvested from the Atlantic Ocean and Pacific Ocean each year.
This article will focus on the American lobster. The American lobster is commercially important for the delicious meat in its claws and tail. This species belongs to a group of lobsters known as clawed lobsters. There are several other lobster groups. Spiny lobsters get their name from the sharp spines on their shells. These lobsters are also important as seafood. They lack claws and their large tail contains much meat. Slipper lobsters, named for their flattened shape, are found mostly in warm waters. Deep-sea lobsters live buried in the ocean bottom at great depths. Most are blind.
The American lobster
Body.
American lobsters are the largest species of lobster. They can measure as long as 42 inches (107 centimeters) and weigh nearly 45 pounds (20 kilograms). However, most lobsters are caught before they reach full size. Captured lobsters generally measure about 8 inches (30 centimeters) long and weigh only about 1 pound (0.45 kilogram) or less.
Like other crustaceans, American lobsters are invertebrates–that is, they lack a backbone. A strong shell called an exoskeleton protects the lobster’s soft body parts. The shell is usually brownish-green with spots. Lobster shells turn bright red-orange when boiled.
The American lobster’s body has 21 segments. The head has 6 segments; the thorax–the center part–has 8; and the abdomen–the tail part–has 7. Where the segments meet, the exoskeleton is thinner, so the lobster can bend its body and move. A lobster breathes through gills beneath the shell on both sides of its thorax.
An American lobster has two pairs of antennae on its head. The animal’s eyes are on the ends of a pair of slender, jointed organs called stalks. Lobsters have compound eyes that consist of hundreds of lenses joined together. The lobster keeps its antennae and eye stalks moving constantly to search for food and to watch for enemies. Its antennae, legs, and shell are covered with millions of tiny hairlike sensors that can detect chemicals. The sensors help the animal locate food.
American lobsters have five pairs of jointed legs attached to the thorax. Four pairs are thin, and the lobster uses them for walking. The fifth pair, which extend in front of the head, are thick and end in large claws. The larger of these two claws has thick teeth to crush prey. The smaller claw has sharp teeth to tear food apart. All lobsters do not have the heavy claw on the same side. Some are “right-handed,” and others are “left-handed.” Leglike structures called swimmerets are located under the abdomen and help the lobsters swim. Female lobsters also use swimmerets to hold eggs.
Life.
American lobsters live on sandy, muddy, or rocky bottom areas. They usually hide in holes or under rocks at depths of 10 to 180 feet (3 to 55 meters). A lobster sits in its burrow all day, waving its feelers outside the entrance. It holds its claws ready and pounces on any prey that comes near. A lobster eats clams, crab, snails, small fish, and, occasionally, other lobsters. They also feed on algae and on plants called eelgrass. At night, it walks along the ocean bottom looking for food. If an enemy such as a large fish or an octopus comes near, the lobster scoots back into its burrow with powerful flips of its tail.
Young.
A female lobster usually produces eggs only once every two years. She may produce 3,000 to nearly 100,000 eggs at a time. The number varies with her size and age. The eggs are covered with a sticky, gluelike substance and are attached to the swimmerets. The female carries the eggs for 10 to 11 months. When the eggs are ready to hatch, the lobster shakes the young out of the eggshells. Newborn lobsters are about 1/3 inch (8 millimeters) long. They rise up in the water and drift and swim about for two to three weeks. At this time, they are easy prey for sea birds, fish, and other enemies. Then the lobsters sink to the ocean bottom where they spend the rest of their lives. Lobsters can live about 15 years or longer. But most never reach this age because they are captured by a variety of predators, including human beings.
Growth.
Lobsters molt (cast off their shells) as they grow. The animal loses its first shell within one week after hatching and molts three more times during the first month. When molting, the lobster’s body gives off a substance that softens the shell. Then, by expanding its muscles, the lobster splits the shell and steps out of it. The new shell, which had formed under the old one, is soft and gives the lobster no protection. The animal hides from its enemies until the new shell hardens.
Lobster fishing
Lobster fishing is an important industry in many areas. Each year, millions of American lobsters are caught off the coast of Maine and farther north in Canadian waters. Spiny lobsters, which live in warm tropical seas, are caught off the coasts of California and Florida and in various parts of the Southern Hemisphere.
At one time, people caught so many American lobsters that the animals were in danger of dying out. Today, fishing laws protect lobster populations.
Lobsters are caught in traps called pots (cages made of narrow pieces of wood or metal). A lobster can enter the pot but cannot find the opening to get out.
The trap is baited with fish and lowered to the ocean floor. A float tied to a cord fastened to the trap shows the pot’s location. The trap is usually raised and emptied every day or so. If two or more lobsters get in, they may fight and injure or kill one another. When a lobster is taken from a pot, each claw must be secured using special rubber bands or wooden or plastic plugs (nails). These tools keep the claws from opening.
