American lobster

American lobsters live in the cold Atlantic Ocean.

They live near Canada and the United States. They like rocky places with lots of hiding spots.

American lobsters live in the northwest Atlantic Ocean, from Labrador in Canada south to Cape Hatteras in North Carolina. They are most common close to the coast from Maine to New Jersey, but some live far offshore in water about 700 meters deep.

Lobsters live on the ocean floor. Near the coast they like rocky bottoms, where they can tuck into cracks and holes. They can also dig burrows in mud. Young lobsters seem to prefer settling where the bottom is covered with loose stones called cobble.

NOAA Fisheries gives a range in the northwest Atlantic from Labrador to Cape Hatteras, most abundant in coastal waters from Maine through New Jersey and common offshore to about 2,300 feet (roughly 700 meters) from Maine through North Carolina. The IUCN assessment lists Canada and the United States as the native range, with depths from about 1 to 700 meters.

This is a benthic animal. Inshore lobsters favor rocky bottoms with shelter, though they also burrow in mud; Animal Diversity Web notes that young lobsters seem to prefer settling on cobble. Small inshore lobsters stay put, while large ones may travel widely, and NOAA reports offshore lobsters migrating 50 to 190 miles in spring. The IUCN also lists Norway, where American lobsters have been introduced.

Lobsters look for food at night.

They eat clams, crabs, snails and little fish. They eat dead animals they find on the sea floor too.

Lobsters do most of their eating at night. They are often scavengers, which means they eat dead animals they find, but they can also catch live food. Their meals include clams, crabs, snails, small fish, algae and eelgrass.

What a lobster eats depends on what is around, so diets differ from place to place. Lobsters are food for other animals too. Fish, sharks, skates, octopuses and crabs all eat them, and young lobsters are in the most danger.

NOAA Fisheries calls lobsters opportunistic feeders whose diet varies by region with whatever prey is most available. Animal Diversity Web describes mostly nocturnal feeding, usually scavenging but also active capture, on clams, crabs, snails, small fish, algae and eelgrass. Food is ground up in a forestomach lined with grinding teeth before digestion.

The young eat differently. NOAA notes that larvae and postlarvae are carnivores that eat zooplankton during their first year. Lobsters are prey for many bottom-dwelling animals, including fish, sharks, rays, skates, octopuses and crabs. Juveniles are most at risk; NOAA notes that large, hard-shelled adults may have no predators except people.

A lobster hides in a rocky home in the daytime.

To grow, it wiggles out of its old shell. Then it eats the old shell!

American lobsters mostly live alone. In the daytime they hide among rocks or in burrows, and at night they come out to find food. If a predator comes near, a lobster darts back into its shelter.

Growing is hard work. A lobster's shell cannot stretch, so it must molt: it climbs out of its old shell and takes in water to swell up before the new soft shell hardens. Afterward it often eats its old shell. That gives back calcium, which helps the new shell harden.

Animal Diversity Web describes lobsters as solitary and nocturnal, sheltering among rocks by day and recognizing each other by chemical cues; in groups they form dominance hierarchies, and high-ranking males hold the best shelters.

Before a molt, the lobster reabsorbs minerals from its old exoskeleton so it can break free; it then takes up water and swells before the new shell, already formed underneath, hardens over a few days. Animal Diversity Web reports a 10 to 15 percent size increase per molt. NOAA Fisheries notes that lobsters eat voraciously after molting, often consuming their own cast shells, which replaces lost calcium. Because the old shell is shed, molting also erases any record of age, which is why lobsters are hard to age.

Many people catch lobsters to eat.

There are rules about which lobsters can be caught. The rules help keep enough lobsters in the sea.

The IUCN Red List lists the American lobster as Least Concern, but that check was done back in 2009. In the United States, lobsters are fished from Maine to North Carolina, mostly with traps called pots.

In the United States, the states and NOAA Fisheries make the rules together. Lobsters in southern New England are in trouble: NOAA says that group is overfished. Scientists think warmer water and low oxygen have harmed lobsters there and may be pushing them to cooler water farther from shore.

The IUCN Red List assessed Homarus americanus as Least Concern with a stable population (assessed 2009, published 2011, and flagged as needing an update). In US waters NOAA Fisheries recognizes two stocks, Gulf of Maine/Georges Bank and Southern New England, and reports that the Southern New England stock is overfished, with management measures in place to promote growth.

NOAA links lobster die-offs in western Long Island Sound in late 1999 and 2002 to a combination of warmer water, hypoxia and other stresses, and researchers think warming in Southern New England may be driving lobsters offshore and disrupting larval settlement near the coast. Scientists believe some lobsters may live to about 100 years, but because molting leaves no record of age, this is hard to confirm.