The American Lobster – The World’s Heaviest Arthropod

Information About the American Lobster

The American Lobster, which scientists call Homarus Americanusis found on the Atlantic Coast of North America. It lives well in cold, shallow waters where there are many rocks and other places to hide from its predators. It eats fish, small crustaceans, and mollusks. It is active during the night and sleeps in the day time. Generally they  have a body size measuring from 20cm to 60cm in length and 1/2 kg to 4kg in weight. However, some American Lobster have been caught which are more than 1 m long and as heavy as 22kg or more. This makes the American Lobster the heaviest crustacean – indeed, the heaviest Arthropod – in the world!

American Lobsters are crustaceans. Crustaceans belong to a huge collection of animals, called the Arthropods, which include the millions of different species of insects, as well as spiders, millipedes, and crustaceans – so the American Lobster is the heaviest among a field of millions of contestants! The American Lobster belongs to a group of Crustaceans called Decapods, meaning “having 10 feet”, which also includes most of the crustaceans we are familiar with – including crabs and shrimp. Within the Decapods, the 400 or so types of lobster and crayfish are placed in a group of their own – scientists call them Astacidae – to distinguish them from crabs and shrimp. So, the American Lobster, as well as being the world’s heaviest Arthropod, is

  • The world’s heaviest Crustacean
  • The world’s heaviest Decapod
  • The world’s biggest and heaviest Lobster

The biggest Decapod and Crustacean is a crab, the Japanese Spider Crab. It is lighter than the American Lobster, but its long spindly legs make it truly enormous!

How Lobsters Moult


American Lobster
The American Lobster is the Heaviest Arthropod in the World!

The lobster can’t grow its hard shell, so it has to replace it when it wants to grow bigger. This is called moulting. They moult two to three times per year while they still young and only once a year or less when they are older. They are considered adult when they are four to seven years old. The way they moult is this – first they grow a new, soft shell underneath the old one. Then the old one becomes very hard and gets darker, finally splitting and falling away. The Lobster then pulls its claws and tail out of the old shell. The new shell expands, and then goes hard.

The American Lobster’s Eyes, Mouth and Legs

They have long powerful antennae which helps them to feel what is happening around them. They have a special sensory organ helps the lobster to locate the direction of a smell. They can also judge water speed. They have amazing eyes and a multi-purpose mouth. The mouth is not only used for eating and burrowing, it can be transformed into a wedge to push gravel and sand or to transport small rocks away. Their mouth can even help them to move around when they have lost their claws and all their legs during a fight!

The first pair of a lobster’s ten legs are called the claws and are usually used for hunting and fighting. They are not used for moving around. The other eight legs are used for walking.  They prefer to live alone. If two lobsters meet, they will size each other up. Normally the weaker and smaller one will retreat. If both lobsters are equally strong and big, they will fight until one of them decides to surrender. What a fighting spirit!

The American Lobster lays eggs and can live for up to 50 years.

Eating Lobsters

Codfish love to eat this kind of lobster, but the creature that eats the most lobster is people. American Lobsters are a popular food. They can be boiled or steamed – but they should be kept alive until they are cooked, so they’ll be fresher. However, they can be safely frozen and refrigerated before eating. Lobsters are usually cooked alive. Some people find this too cruel, so they refuse to eat them.

One thought on “The American Lobster – The World’s Heaviest Arthropod”

  1. This is so cool. I did not know some lobsters could weigh 44 pounds. That is so much. The heaviest arthropod in the world. Amazing.

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