Lobsters

The exoskeleton of living lobsters is greenish black in color, but turns red if the animals are boiled in water An American lobster. JLM Visuals. Reproduced by permission.

or steamed, as when prepared as a meal for humans. Like many crustaceans, lobsters do not have a terminal molt—they appear to keep growing until they die an accidental death, are predated, or develop a fatal disease. The largest of the typical lobsters can exceed 44 lb (20 kg) in weight, more than half of which is made up of their enormous foreclaws.

Both groups of lobsters are scavengers of all types of dead animals, detecting the presence of food using their well-developed sense of smell. Both types of lobsters, but particularly the typical lobsters, are also predators of a diverse range of other invertebrates, including cannibalism of other lobsters. The typical lobsters are very effective predators, because their large, powerful claws can crush and cut even seemingly well-protected prey.

Lobsters are most active at night. During the day they typically hide in burrows or cavities in rock piles, which they enter by backing in. Lobsters can crawl in all directions, but when they are foraging they mostly proceed in a forward direction. Smaller lobsters can swim jerkily, by rapidly back-flipping their tail fan.