Sperm whale diving.
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.
Their angled, bushy blows make them easy to spot even though they rarely show much more above the surface.
These animals are widespread around the world, but have a patchy distribution. They prefer deep water (>200m) and so are usually found offshore and in areas with submarine canyons, such as Kaikoura, where sperm whales are present all year round.
They generally move towards the poles in summer, males more so than females and juveniles. Females usually inhabit water deeper than 1000 m at latitudes less than 40-50°. Male distribution extends to more temperate latitudes.
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. Original public domain image from Flickr