Lobster Anatomy: Understanding the Lingo and Parts of a Lobster

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Understanding the anatomy of a lobster is crucial for anyone interested in the biology of these fascinating crustaceans. Lobsters are known for their hard exoskeleton, which protects their soft internal organs. In this guide, you will learn about the different parts of a lobster’s body and how they function.

The External Anatomy of a Lobster

Maine Lobster Anatomy Dorsal View

Here is a little primer on the parts of the lobster so you know what you are cracking into! Speaking of eating lobster, learn how to crack and eat a whole lobster.

Shell: The shell is the lobster’s skeleton and cannot grow; it instead must be shed through a process called “molting.” Find out why molting is vital in buying an excellent hard-shell lobster.

Antennas: Lobsters have four long and thin antennas covered by tiny hairs, which allow them to smell.

Stalks: Lobsters have eyes on long, thin structures called stalks. Find out more about lobster’s compound eyes.

Lobster Anatomy Ventral View

Carapace: It is the armor-like body of the crustacean with the claws, knuckles, and tail removed. It houses the legs, the tomalley (see below), and, in the females, the roe (see below). In the State of Maine, legal lobsters are measured by shell length. Lobsters under 3 ¼ inches or over five inches must return to the water.

Legs: Lobsters have 10 legs. The four pairs of legs contain small strips of meat that take some work to remove. Lobsters use the eight back legs to walk. The front legs have claws called pincers.

Claws: Lobsters use their claws to catch food and battle predators and other lobsters. The larger of the two claws is called the crusher claw, and the smaller claw is called the pincer or cutter claw. The claws of hard-shell lobsters are full of tender, sweet meat.

Knuckles: The two joints connect the large claws to the carapace. Connoisseurs say the knuckle meat is the tastiest.

Tails: The tail holds the biggest piece of meat in the lobster.

The Internal Anatomy of a Lobster

Internal Anatomy Lobster

Digestive System: Lobsters have a three-part digestive system – foregut, midgut, and hindgut. The foregut breaks down food, the midgut absorbs nutrients, and the hindgut eliminates waste. They also have grinding teeth for breaking down hard-shelled prey.

Circulatory System: Lobsters have an open circulatory system, meaning their blood is not always contained within blood vessels. Instead, their blood flows through a series of sinuses and cavities. Lobsters have clear-colored blood that turns blue due to copper in their blood cells. Their circulatory system also includes a heart, which pumps blood throughout their body.

Nervous System: Lobsters have ganglia throughout their body, allowing them to react to stimuli and sense their surroundings. They also possess compound eyes and antennae to navigate their environment.

Respiratory System: Lobsters breathe through the gills in their abdomen. Water flows over the gills to extract oxygen. Swimmerets on their abdomen help move water over the gills.

Reproductive System: Male lobsters have a pair of reproductive organs called testes, while female lobsters have ovaries. During mating, the male transfers sperm to the female using specialized appendages called gonopods. Female lobsters carry fertilized eggs on their pleopods (swimmerets) until they hatch into larvae.

Lobster Sizing Names

  • Shorts or Snappers: A lobster under the legal size limit.
  • Canners: Small lobsters approximately 1/2 to 1 pound. They took their name in the 1880s because these size lobsters were “canned” and sold on shelves.
  • Market:  A size category for lobsters available for sale ranging from 1 to 3 pounds.
  • Chickens: A lobster weighing about 1 pound.
  • Culls: A lobster that has lost one or both claws. Generally sold at a lower price.
  • Quarters: A lobster weighing 1-1/4 pounds.
  • Selects: A lobster weighing from 1 ½ to 1 3/4 pounds. Buy select lobsters.
  • Deuces: A lobster weighing about 2 pounds. Buy deuces or 2 lb. lobsters.
  • Jumbos: A lobster weighing over 2-1/2 pounds. Order jumbo lobsters!

What Is the Best Part of the Lobster to Eat?

The tail is the most substantial part, while the claws are tender and succulent. The knuckles, legs, and body meat are also popular choices. Lobster is a healthy seafood, high in protein and low in fat. Enjoy a delicious and nutritious meal with any part of the lobster!

The Stuff Inside Your Lobster

What is the Red stuff inside a lobster?

The red stuff is the “coral” or tiny lobster eggs of the female lobster. The eggs are aso called spawn. It is found at the base of the body and along the tail. The roe is black uncooked, but the color can vary depending on the lobster’s diet. Lobster eggs were once considered a delicacy, like caviar. A fertile adult female lobster produce about 10,000 eggs, all about the size of a pin head. Only 1% of those eggs will make it into adulthood.

These lobster eggs are held toether with a natural pectin (orglue) which adds to the sweet flavor of the eggs (roe). After these eggs are fertizlized by the make, they are carried by the mother for almost a year on the outside of the female lobster, underneath her tail. They hatch in a few months as larva but look nothing like an adult lobster. Lobstermen will not interntionally catch females that are visibly carrying these fertilized eggs on the outside of her body.

What color is the blood of a Lobster?

The blood of a lobster is not red, but clear before it is cooked. You will find most of it in and around the claws. The lobster blood looks like egg whites, uncooked and transparent. Aftercooking, the lobster blood turns to a white chalky-gel substance. It is tastelss and odorless and ok to eat. Try it in sauces.

What is the green stuff inside a lobster?

The liver and pancreas are the light-green tomalley (hepatopancreas) in the lobster’s carapace. Although lobster lovers adore the rich as butter tomalley, it should be eaten sparingly. As with other animals, contaminants may settle in the liver, so it’s best to be safe.

Does a lobster have a brain?

The lobster’s brain is part of a primitive central nervous system and is located inside the head. If you split open the head of a lobster, you will see an interesting part of New England folklore. It resembles the figure of the Virgin Mary with two angels praying on each side. This image is in perfect 3 dimensional resolution and ca be seen from all angles.

Do lobsters have teeth?

If you are looking for teeth of the lobster, you may be looking in the wrong place. It does in fact have teeth, but they are located in its stomach.

Interested in ordering live lobster online, but unsure of what size to buy? Here are some tips on what size lobster to order.

What part of the lobster can’t you eat?

There is no part of a lobster that is poisonous. There are some intresting things to note about the internal lobster parts.

Instestinal Vein: The dark instestinal vein should always be removed before eating. It is ok to eat but sometimes can give you a bitter taste. THis vein is a dark bluish-gray and runs from the center body to the tail on the underneath portion of the lobster.

The stomach: The stomach of the lobster is caled the “sac”, (also called the grain sac or sand sac). It is located behind the eyes of the lobster. The sac should be removed according to most recipes. It sometimes contains small shell or bone fragments from food or bait that the lobster has eaten.

To remove the head sac just take a sharp chef knife to split the head of the lobster open lenghthwise and remove.

Lobster Anatomy Quick FAQS

A Maine lobster has how many body parts?

A Maine lobster has 19 body parts!

What color is the lobster’s blood?

Lobster’s blood is colorless and, when exposed to oxygen, turns to a blue tint. The blue hue is due to the iron the lobster’s body uses to transport oxygen. Human red-colored blood is due to iron being the oxygen carrier.

When lobsters are cooked, the blood turns to a white, opaque color with a gel-like consistency. It is safe to eat.

What is the red stuff in the lobster?

The hard red substance is the roe or the eggs of the female lobster. It is also called coral because of its deep red color. The roe will be black and will appear gelatin-like if your lobster is undercooked. It is edible but can also be rinsed out.

What’s that green stuff in the lobster?

The greenish gray substance inside the lobster is the liver, also known as tomalley. The tomalley functions as a combination of a liver and pancreas of the lobster. It can be rinsed out of the cooked lobster.

Why is my lobster is missing a claw?

On occasion, a lobster will drop its claw as a defense mechanism. This can happen in shipping and the wild. Lobsters will battle other lobsters over territorial rites.

A lobster with only one claw is called a Cull and is often a good deal at the local lobster pound.
It can take several molts for a lobster to grow back its claw. Cooking your lobster with its dropped or broken-off claws is fine if it arrives alive.

What color is a Maine lobster?

The American lobsters are usually bluish-green to brown with red spines when uncooked. However, an estimated one in 2 million lobsters are blue. Lobsters only turn ‘red’ when cooked.

Does a lobster have a nose?

A lobster does not have a nose, but can “smell” with tiny hairs that cover the front of the lobster and its two small antennae.

Is it necessary to remove the black vein inside the tail before eating?

It will not hurt you, but it should be removed because it is the instenine and part of the diggestive system and does not taste good.

Is a crayfish a baby lobster?

Not at all. Crayfish are related to lobsters, but they live in fresh or bracking water, while Maine lobsters onlky live in cold saltwater.


  1. This was fascinating information, thank you! And I enjoyed the humor. I bear no ill will to anyone who farms, fishes or eats lobster, but this all confirms that I could never eat one, although I’m sure they’re delicious. (For 40 years I was veg, then sadly, for health reasons, began to eat birds and fish.) Lobsters are just to amazing to eat. And remember the one that became a news story a few decades back? 150 years old and walked the ocean floor to the US East Coast from Asia! Incredible accomplishment! More than I’ve ever done. Couldn’t eat ’em.

    If you have time for a Q, can a lobster survive in the wild if it has lost both its claws? Can it even eat, if has only one? Seems like killing and eating would be a two-claw job. Anyway, thanks so much for the history and anatomy lesson!

      1. True, although it takes about 5 years for the new claw to get to the size of the one they previously had.
        As far as the original question, they are still technically able to eat somewhat using their pincers. The biggest risk to being clawless would be predators and other lobsters, but yes some do live without them.

  2. Since this is lobster lingo, the correct terminology is tomalley (from the Carib word tumale, meaning a sauce of lobster liver), not tamale, (from the Spanish word tamal, plural tamales, in Mesoamerican cuisine, a small steamed cake of dough made from corn).

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