
One of the most abundant organisms in Antarctic waters, the Antarctic krill (Euphausia superba) is a keystone species of the Southern Ocean ecosystem, playing a crucial role within the food chain as the main prey for a wide variety of predators, including fish, penguins, seals and whales. A small crustacean which is relatively shrimp-like in appearance, the Antarctic krill has a hard, calcified exoskeleton which is divided into three sections: the head and the thorax (which are fused into what is known as the cephalothorax), and the abdomen. Each section is further divided up into individual segments, with many of the segments having a pair of appendages. At the end of the abdomen, the appendages are flattened and form the tail fin, or telson.