Life of the American Lobster - Anatomy & Biology
Lobsters are classified in the phyllum Arthropoda (which also includes shrimp, crabs, barnacles, and insects.) The word Arthropoda comes from the Latin word “arthro”, meaning jointed, and the Greek word “poda”, foot. Hence, you will note the lobster has jointed appendages…and since lobsters are also decapods (“deca” being Greek for ten) it has ten legs (five pairs).
As invertebrate crustaceans, lobsters also have a hard outer shell or exoskeleton, and no inner skeleton or bones.
The lobsters nervous system is very primitive. In fact it is most similar to the nervous system of an insect. Neither insects nor lobsters have brains. Further, lobsters and other invertebrates have only approximately 100,000 neurons while humans have over 100 billion.
A lobster’s blood is usually greyish/clear in color. It is circulated by a heart located just behind the stomach, through a few large blood vessels. It picks up oxygen from the water through the gills, found in the lobsters’ thorax section.
Here are the basic parts of a lobster:
- Abdomen — the section commonly referred to as the “tail”.
- Antennae — tactile organs, having a sense of touch.
- Antennules — chemosensors, having a sense of smell – with a function similar to a human nose.
- Carapace — the outer shell of the cephalothrax
- Cephalothorax — contains the head and thorax sections — together they are commonly called the “body”
- Chelipod (crusher claw) — the larger of the claws, with a rounded surface suitable for crushing prey such as shellfish.
- Chelipod (ripper or pincher claw) — the smaller of the claws, which is more pointed and sharp, is used for tearing food apart.
- Eye — compound eyes provide sense of sight
- Mandible — jawlike structure for crushing and ingesting food
- Maxillipeds — the mouthparts of the lobster, flat platelike parts used to pass food to the mandible
- Pereiopods (walking legs) — The two sets of walking legs immediately behind the claws are also used for catching and eating food and have many “taste” sensors; the last two sets of legs are used primarily for walking.
- Pleopods — commonly known as “swimmerets”. with tiny hairs. In females the hairs are somewhat longer and are the attachment point for eggs.
- Telson — the central tail fin
- Uropods — the outer pairs of tail fins
There are many informative Web sites dealing with lobster anatomy and biology that provide more detailed information. We have provided you with several links (in alphabetical order) that should give you most information you are looking for. We at the Lobster Institute are happy to answer any questions you may have as a follow up to your online research.
Lobster Biology Links
- Gulf of Maine Aquarium
- Lobster Conservancy
- Rhode Island Lobstermen’s Association