Northern Lobster - Homarus americanus

Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Nephropidae
Genus: Sterna

Description

Lobsters are part of the Arthropoda phylum. They are related to insects! Like insects, they have an exoskeleton. Like most arthropods, the lobster is bilateral. That means that if you cut a lobster in half from head to tail, the two halves would be exactly the same!

The lobster has two distinct sections of its body. The cephalothorax includes the lobster's head and thorax, or mid-section.

The cephalothorax is covered by a hard shell called the carapace. The carapace is what is measured to determine whether a lobster is large enough to keep. The lobster sheds its shell or molts as it grows. The second part of the lobster is the abdomen. The abdomen is often called the tail. The lobster has five pairs of legs. It has pinchers on the first three sets of legs. The front pair of legs have very large pinchers or claws. One of these claws is called the pincher claw and the other one is called the crusher claw. The crusher claw is the larger claw and is used to crush prey. The pincher claw is used to rip into the prey. Lobsters can be right or left handed, depending on which side the crusher and pincher claws are found!

The lobster has compound eyes on movable eye stalks. Its eyes have up to 14,000 little lens, but the lobster doesn't have very good eyesight! It mostly uses its eyes to detect movement. It relies on its antennae to locate food! It has two sets of antennae. One set, called the antennules, are short. The lobster uses the chemical receptors on these antennules to locate and identify food by its odor!

The lobster is greenish-brown or brown in color. It is only red when it is cooked! The red comes from a pigment in the lobsters shell called astaxanthin. Astaxanthin is chemically bound to proteins in the lobster's shell. When a lobster is cooked, the heat breaks down the chemical bond and the astaxanthin is freed, turning the lobster red!

Range

The northern lobster is found from from the coast of Labrador, Canada south to Virginia.

Habitat

The northern lobster is found on the rocky bottoms of cold, shallow waters from the shoreline to the continental shelf. It prefers rocky areas where is can find places to hide from predators!

Diet

Many people think the lobster is a scavenger and eats only dead animals. The lobster is not a picky eater, but it does eat mostly live food! It eats a wide variety of live food including crabs, mussels, starfish, marine worms, shrimp, and even some plants. It may also eat some dead meat or carrion.

Life Cycle

The female lobster can only mate right after molting. She uses chemical communication to attract a mate and releases a pheromone or chemical that lets the male know she is ready to mate. The male deposits his sperm in the female. The female can carry the sperm in a seminal receptacle for up to 15 months. When she releases her eggs, they pass by the seminal receptacle and are fertilized by the sperm. The female can carry tens of thousands of eggs at a time.

Lobster larvae molts four times in the first 10 to 20 days. In these first days, the larvae are found near the surface of the water. Eventually, the young lobster is large enough to sink to the ocean floor. The young lobster molts 10 more times in its first year. At the end of its first year, it is about an inch in length. It takes a lobster up to six years to grow to a weight of one pound! Lobsters can live as long as 50 years!

Behavior

The lobster is a solitary creature. It can also be very aggressive with other lobsters! Lobsters may threaten and shove at each other with their claws.