At six centimetres adult length and over a gram in weight, most people comment on how big krill are. The constant underestimation of the size of krill is probably the result of a general lack of public awareness about them and their importance in the Antarctic ecosystem. The animals most commonly depicted in books and articles about the Antarctic are the whales, seals and penguins but seldom is much space given to the animals that are their prime food source. Most pictures of krill are either drawn or photographed from dead or dying specimens. Krill are difficult to keep in aquariums so most biologists have to be content with studying them pickled.
Dead krill are opaque and their bodies are usually curled up.
When they are alive, however, they present a much prettier picture. They are mostly transparent, although their shell is tinged a bright red by small pigment spots. They have large black eyes and a digestive system that is often vivid green from the pigments of the microscopic plants they have eaten. Their overall appearance is quite beautiful and very different to the evil-smelling specimens preserved in formalin in laboratory jars. Krill is a general term used to describe about 85 species of open-ocean crustaceans known as euphausiids.