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
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Here is a little primer on the lobster parts so you know what you are cracking into! Speaking of eating lobster, learn how to crack and eat a whole lobster.
Primarily the lobster’s body is composed of twenty-one segments. Seven segments comprise the abdomen (commonly known as the tail), six comprise the head region, and the remaining eight comprise the thorax. The lobsters belong to the family of decapods (meaning ten feet). They have ten legs, and two legs near the head region have claws at the end. Other important parts of the lobsters include:
Antennae: The lobsters possess three pairs of antennae covered by tiny hairs, two pairs of smaller antennas, and one pair of larger antennae. The lobsters use their large antennae to find their way around and touch. The smaller antennae allow them to identify various chemical signals in water. Moreover, they help lobsters to smell odors and thus identify the food.
Eyes: Lobsters have compound eyes held in thin and long structures called stalks. The eyes are located beneath the antennae. The eyes are extremely sensitive to light, cannot differentiate between colors, and cannot see images. Nonetheless, they can detect shadows and movements.
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.
Stalks: Lobsters have eyes on long, thin structures called stalks. Find out more about lobster’s compound eyes.
Carapace: The carapace (hard shell) covers the lobster from head to tail. 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.
Pleopods: Lobster’s swimmers, or swimmerets, are located along the tail and can be seen when the lobster is lying on its back. Commonly known as “swimmerets”. with tiny hairs. swimmerets or “pleopeds” are the appendages just behind the legs at the base of the tail.
Claws: Lobsters use their claws to catch food and battle predators and other lobsters. There are two claws; the larger one, having a round surface, is known as the crusher claw or cheliped. It is used to fight against predators or crush the prey. The smaller one, sharp and pointed, known as cheliped is used to break apart food. 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. Females have smaller claws than their male counterparts.
Knuckles: The two joints connect the large claws to the carapace. Connoisseurs say the knuckle meat is the tastiest.
Tail: The tail helps them to move around in water. When the lobster needs to escape, it contracts its tail forcefully and rushes backward. Females have larger tails than males. Tails have the largest proportion of meat in a lobster.
The Internal Anatomy of a 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. Lobsters 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 also 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 produces about 10,000 eggs, all about the size of a pinhead. Only 1% of those eggs will make it into adulthood.
These lobster eggs are held together with natural pectin (or glue), which adds to the sweet flavor of the eggs (roe). After these eggs are fertilized by the maker, 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 larvae but look nothing like an adult lobster. Lobstermen will not intentionally catch females visibly carrying these fertilized eggs on the outside of their bodies.
What color is the blood of a Lobster?
Before it is cooked, lobster blood is not red but clear. Most of it is in and around the claws. The lobster blood looks like uncooked and transparent egg whites. After cooking, it turns into a white, chalky gel substance. It is tasteless, odorless, and okay 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 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 has a perfect three-dimensional resolution and can be seen from all angles.
Do lobsters have teeth?
If you look for the lobster’s teeth, you may look in the wrong place. The lobster 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?
No part of a lobster is poisonous, but there are some interesting things to note about the internal parts.
Intestinal Vein: The dark intestinal vein should always be removed before eating. It is okay to eat it, but sometimes it can give you a bitter taste. This dark bluish-gray vein runs from the center body to the tail on the underneath portion of the lobster.
The stomach: The lobster’s stomach is called the “sac” (grain sac or sand sac). It is located behind the lobster’s eyes. According to most recipes, the sac should be removed. It sometimes contains small shell or bone fragments from food or bait that the lobster has eaten.
To remove the head sac, use a sharp chef’s knife to split the lobster’s head open lengthwise and remove it.
Lobster Anatomy Quick FAQS
A Maine lobster has 19 body parts!
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.
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 appear gelatin-like if your lobster is undercooked. It is edible but can also be rinsed out.
The greenish-gray substance inside the lobster is the liver, also known as tomalley. The tomalley functions as a combination of the liver and pancreas of the lobster. It can be rinsed out of the cooked lobster.
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.
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.
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.
It will not hurt you, but it should be removed because it is the intestine and part of the digestive system and does not taste good.
Not at all. Crayfish are related to lobsters but live in fresh or brackish water, while Maine lobsters only live in cold saltwater.
No, they have a jaw-like structure known as a mandible which is used to crush and pass the food allowing them to consume a variety of prey with ease
Yes, they have the central tail fin known as telson, which aids in locomotion and balance, and outer pairs of tail fins known as uropods, which help smooth underwater movement.
In total, there are 10 legs. Two legs near the head are the claws, which are used for both defense and capturing prey, and the remaining eight legs are primarily dedicated to walking.
Yes, when raw, lobster roe tends to be dark, almost black in color. However, once cooked, it transforms into a bright red hue making it more appealing for consumption.
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!
Their claws grow back 🙂
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.
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).
Thanks for spotting the typo and the etymology information. While some lobster lovers love the tomally, I would rather have a chicken tamale!