Sperm whales (Physeter macrocephalus) have wrinkly skin and a large rather square
head that makes up around one third of their body length. Females are smaller than
males and have a proportionately smaller head. They are purplish-brown or dark grey
in colour, with white underneath. The dorsal fin has been reduced to a low hump and
there is only one, slit-like blowhole, situated on the top left side of the snout.
Adult Sperm whales grow up to 18 m in length.
Kaikoura is home to the main New Zealand population of sperm whales, including both
resident and transient individuals. It appears that there is no other area in the
world where this species is routinely found so close to the coast. Sperm whales are
toothed whales and dive to great depths to feed. They eat large organisms, mainly
squids, but males are also likely to eat demersal fish including sharks and rays.
They are thought to feed using clicks, which can both locate and possibly stun their
prey. Dives have been known to last for over one hour and can be deeper than 1000
m. Most dives tend to last around 35 minutes however, extending down to 400 m.