Spinner dolphins average six ft. in length and have a slender body, a long thin head and large flippers. Their typical behavior is to appear in large collections unless they feel wary and shy of the boats. But most of them are still sparked into a running frenzy by the approach of the motor. Normally the entire school explodes into action, towards or away from the vessel, churning the water up into boiling foam with their rapid leaping movements. Most dolphins make a series of very long jumps, but every few seconds one or more schools hurls itself high into the air, twisting their bodies or simply spinning over.
Spinner dolphins feed on small fish and squid, often several hundred feet down.
These foods may be what draws this dolphin together with yellowfin tuna. In contrast to Spinner, the Common dolphin averages about seven ft. in length and is sleek, streamlined and spindle shaped, with a long beak, a moderately pointed fin and pointed flippers. The color is deep Grey above and light Grey below, but is complicated by the most elaborate flank markings to be found on any cetacean. Common dolphins are usually found in large active schools, often churning up a wide area of water. There seems to be more variety, more individuality, in their swimming style than in any other species.