The young pelagic fishes look different enough from their adult form that they were classified at one time as a separate subfamily.
And sharks that range across the open ocean, known as oceanic or pelagic sharks, have been an even bigger mystery.
Aquatic ecologists have many models for size distributions of pelagic communities.
However, aside from anecdotal reports of color changes in various pelagic fish, particularly billfish, little else is known.
Among coastal river otters in this region, sociality could be explained by the benefits obtained from cooperative foraging on high-quality schooling pelagic fishes.
Of the fishes, several pelagic species were found in many of the habitats sampled.
Farmed salmon eat two to five pounds of protein for every pound of weight gained - protein that comes from small pelagic fish like anchovies, mackerel, herring, and sardines.
These sites provide the most exciting diving, with shoaling barracuda and other pelagic fish, but sadly they tend to be few and far between.
The silvery sheen displayed by many pelagic fishes is an example of structural color.
While blue whales may occasionally feed on pelagic crabs and small fishes, their diet is almost exclusively euphausiid shrimps commonly called krill.