DIVERSITY OF SIZE IN DELPHINIDAE FAMILY “ With 32 species placed in 17 genera, this is by far the largest family of cetaceans. Delphinids are small to medium-sized cetaceans, ranging from about 1.5 m in length and 50 kg weight to almost 10 m in...

DIVERSITY OF SIZE IN DELPHINIDAE FAMILY

With 32 species placed in 17 genera, this is by far the largest family of cetaceans. Delphinids are small to medium-sized cetaceans, ranging from about 1.5 m in length and 50 kg weight to almost 10 m in length and 7000 kg.

the shape of the head of many delphinids is distinctive; the forehead appears to bulge over the beak-like rostrum due to the presence of a lens-shaped fatty deposit called a “melon.” This structure may help focus the sound emitted by these animals in echolocation and feeding. Other delphinids possess a melon, but their rostrum is short and the bulging forehead merely gives the head a squared-off appearance. The bodies of most species are sleek and streamlined. Most have dorsal fins, which are usually curved (falcate), but much variation exists. Some species have striking color patterns over their bodies; others are more or less uniform. The group includes bottlenose dolphins, killer whales, pilot whales, Pacific striped dolphins, and many more.

The orca (killer whale) is the largest dolphin, and the Hector’s dolphin is the smallest.