Within the crustaceans, the Amphipoda rank as one of the most speciose extant orders. Amphipods have successfully invaded and become major constituents of a variety of ecosystems. The hyperiid amphipods are classically defined as an exclusively pelagic

Collection of live planktonic animals by divers has confirmed that hyperiid amphipods in the genera Vibilia and Lycaea are specific and obligate symbionts of salps. Species in the genera Brachyscelus, Parathemisto, Oxycephalus and Phronima are also sometimes

Hyperiid amphipod species from the Gulf of Ulloa, Baja California, and the adjacent region (from the shelf break to 200 km offshore) were analyzed to evaluate diversity and abundances. This productive area supports small-scale commercial fisheries, including