The Eucarida form a super order of the Malacostraca.
There are three orders, of which the decapods or Decapoda is the best known, including the most animals that seem like crustaceans, including the lobsters, crabs, shrimps.
The second order, Euphausiacea, contains species of crustaceans called krill, which often remain smaller but form an important source of food for much larger sea creatures. The numbers are sometimes so large that the krill masses can be seen from space.
The third order, Amphionidacea, is special because there is only one type of crustacean that belongs to it; Amphionides reynaudii. This species mainly deviates because certain parts of the body, such as the mouth parts, are strongly reduced or even missing. Order
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