The Hyperiidea are a suborder of amphipods, small aquatic crustaceans. Unlike the other suborders of Amphipoda, hyperiids are exclusively marine and do not occur in fresh water. Hyperiids are distinguished by their large eyes and planktonic habitat. Most species of hyperiids are parasites or predators of salps and jellyfish in the plankton, although Themisto gaudichaudii and a few relatives are free-swimming predators of copepods and other small planktonic animals.
Taxonomy
According to Vinogradov et al., 233 species of Hyperiidea are known.
Some controversy exists as to the number of families in the Hyperiidea, being given as between 20 and 23 depending on whether groups like the Thaumatopsidae are considered distinct or not. Here is the conservative list of 20 families:
Distribution
Hyperiidea are known from many oceans of the world, including 69 species in the Southern Ocean.
