Lobsters have three pairs of antennas: a large pair and two small pairs. They are sensory organs. The large antennas are used particularly for touching, and allow lobsters to find their way in their environment. The small antennas allow them to recognize various chemical signals in water. They are very sensitive to odors and help them locate food. They have two eyes located at the base of the antennas. They do not distinguish colors and do not see clear images; however, their eyes are very sensitive to light, and they are able to detect movement and shadows even though there is very little light. They find their way around mostly through touching and detecting odors. Their first pair of legs are very large claws. There is a claw to crush and a claw to cut. The crusher claw is bigger and has large "teeth" that enable the lobster to break their preys shell. The cutter claw is slightly smaller and has several little "teeth" that enable the lobster to tear or cut their preys flesh. It also allows lobsters to quickly grab their prey.The four other pairs of legs are used for locomotion. The two pairs located just after the chelae have small claws and are also used for eating. The lobster's head and thorax are welded together and form the cephalothorax. The cephalothorax ends in a tip located between the two eyes, called the rostrum. The rostrum protects the eyes when lobsters clash. The telson is at the end of the abdomen. It is the segment in the middle of the spread tail. Under the abdomen, there are appendages resembling small fins. Those are the swimmerets. There are 5 pairs. The first pair, closest to the cephalothorax, can be used to differentiate males from females. For males, the first swimmerets are large, hard, white, and are used for mating. They are called gonopods. For females, they are small and soft, as you can see in the bottom right picture. They are also used to carry and ventilate eggs.The other pairs of swimmerets help lobsters move. The mouth is just below the rostrum, under the eyes and between the antennas. It includes the maxillipeds and mandibles. Lobsters use the maxillipeds to bring food to the opening of the mouth and the mandibles act as teeth.