Risso's Dolphin

Risso's dolphin has a blunt, square-shaped head without the prominent beak typical of many dolphins. Its robust front body narrows toward the tailstock, while the dorsal fin is tall and curved and the flippers are long, pointed, and recurved. A shallow groove along the melon is distinctive. Young dolphins are dark gray to brown, but accumulated scars and fading pigmentation can make older adults appear almost white. Adults measure 2.6–5 m and generally weigh 300–500 kg. (Animal Diversity Web)

This dolphin inhabits temperate, subtropical, and tropical oceans worldwide, favoring deep water along continental-shelf edges, submarine canyons, seamounts, and steep slopes. Social groups are organized partly by age and sex and commonly contain three to twelve dolphins, although far larger aggregations occur. Risso's dolphins use echolocation and varied whistles, clicks, grunts, and barks. They feed mainly at night on cephalopods, especially paper nautiluses, while also taking fish, krill, and other crustaceans, often hunting 600–800 m below the surface. (Animal Diversity Web)