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. Original public domain image from Flickr