Habits

The female American lobster carries fertilized eggs on the underside of its abdomen until the eggs are ready to hatch. The eggs are covered by a sticky cement that hardens and holds them in place. Eggs of the spiny lobster are released to float in the ocean shortly after they have been fertilized. The newly hatched lobsters do not resemble the adults for several weeks, during which time they go through various stages of development.

The lobster molts, or sheds its shell, frequently while young, less frequently as it grows. After molting it is helpless against predators and must hide until the new shell hardens. If it loses a claw or a leg, the lobster grows a new one. Lobsters mature at four or five years of age. Females, depending on their size, produce 3,000 to 100,000 eggs at one time.

It is hard for lobsters to grow. A lobster is, in a sense, trapped in its exoskeleton, because its shell cannot grow larger. For its body to grow larger, a lobster must discard its shell and replace it with a bigger one. This process is called molting.

Before a lobster molts, it forms a new, soft exoskeleton underneath its existing shell. When the lobster is ready to molt, it seeks out a protected place; it is vulnerable to attack until its new shell hardens.

To molt, the lobster shrinks the muscles and other tissues in its limbs by releasing fluid out of the tissues. This lets the lobster withdraw its appendages from the surrounding shell. Once the shell cracks, the lobster is able to withdraw its entire body from its old shell.

After it is out of its shell, the lobster takes in water to swell its body to a larger size. The new soft shell can withstand the pressure from the lobster’s swollen body without cracking. It takes several weeks for the new shell to harden around the swollen lobster. Once the new shell is hard, the lobster pushes the excess water out from its body. It now has a new, roomier shell to grow into.

On its antennae, legs, carapace, and tail, a lobster has tiny, hairlike receptors that can detect specific chemical molecules in the environment, which help the lobster to identify and locate food. The lobster crawls over the bottom of the sea, eating dead and living fish, starfish, clams, and other animals and seaweed. It grinds its food with six pairs of jaws. The food is then further ground and mixed with digestive juices in the stomach, which contains toothlike grinding organs.

A lobster does not smell with a nose, taste with a tongue, or hear with ears. Instead, the animal has special sense organs for collecting information about its marine environment.

Much of the information a lobster gets about its surroundings is gathered by millions of tiny hairlike sensors on its antennae, mouthparts, legs, and shell. Some of these sensors “sniff” chemicals that help lobsters locate and taste food.

Others warn lobsters of predators or alert them to potential mates.A lobster also has special organs located at the base of its antennules, as the shorter pair of antennae are called. These organs are pits that are lined with tiny bristles. As a lobster moves, particles that are floating within the pits bend the tiny bristles in different directions. Signals that are sent from these bristles through the lobster’s nervous system help the lobster determine its position in its surroundings and keep its balance.

In autumn some species of spiny lobsters take part in mass migrations in search of food and warmer waters for mating. As many as 100,000 individuals move south, by both day and night, in single files of about 60 individuals each. They cover about 10 miles (16 km) a day.

To protect themselves from predators, fish swim in schools. Birds fly in flocks. And lobsters “march.” Predators often have a difficult time capturing prey traveling in such groups.

During a lobster march, dozens of spiny lobsters walk together in long rows, like ants or soldiers. The lobsters walk so close together that the antennae of one lobster may touch the tail of the lobster in front of it.

In the Caribbean Sea, lobster marches are often observed after a storm. At these times, the lobsters are usually marching out to deeper water. Some people believe that storms trigger lobster marches. Scientists, however, are not sure why spiny lobsters march to other locations. Are they moving to deeper waters to protect themselves from winter storms? Are they looking for new breeding grounds? New feeding grounds? The answer remains a mystery.