North American Lobster Head
The American Lobster (Homarus americanus) is a marine invertebrate which inhabits our Atlantic coastal waters. As an invertebrate, it lacks bones, but it does have an external shell, or exoskeleton, making it an arthropod like spiders and insects. Its body is divided in two parts: the cephalothorax (its head and body) and its abdomen, or tail. On its head, the lobster has eyes that are very sensitive to movement and light, which help it to spot predators and prey, but are unable to see colours and clear images. It also has three pairs of antennae, a large one and two smaller ones, which are its main sensory organs and act a bit like our nose and fingers. These antennae are able to smell the water to locate prey and touch elements in the lobster’s environment so it can find its way. The lobster’s mouth is located just below its eyes. Around its mouth are small appendages called maxillipeds and mandibles which help direct food to the mouth and chew. Food is then brought to the first of the lobster’s two stomachs, which is just inside its mouth! The lobster’s respiratory system is made of gills, like fish, which are situated on each side of its cephalothorax.
North American Lobster Showing Its Different claws
The lobster’s legs are also found on the cephalothorax. Lobsters have ten legs, making them decapod (ten-legged) crustaceans, a group to which shrimp and crabs also belong (other arthropods have a different number of legs, like spiders, which have eight, and insects, which have six). Four pairs of these legs are used mainly to walk and are called pereiopods. The remaining pair, at the front of the cephalothorax, are called chelipeds and each of those limbs ends with a claw. These claws help the lobster defend itself, but also capture and consume its prey. Each claw serves a different purpose: the bigger, blunter one is used for crushing, and the smaller one with sharper edges, for cutting. The claw used for crushing can be on the lobster’s right or left side, making it “right-handed” or “left-handed”. When a lobster’s limb, claw or antennae becomes damaged or lost, it is regrown when the lobster moults, a process called autotomy or regeneration. Hairs on the lobster’s legs and claws also act as sensory organs and are able to smell.
North American Lobster Missing A Claw