Sperm Whale: factfile

Size: Up to 20m (males); 12m (females)

Maximum weight: 57 tonnes (males); 24 tonnes (females)

Colouring: Grey to grey-brown, white lips, flecked with white blotches from naval

Blow type: medium height, angled forward at about 40 degrees from tip of snout

Distribution: Worldwide, common throughout western south Pacific, Tasman Sea and New Zealand waters.

Seasonal movements: In winter, females move into warm temperate and tropical waters to calve and suckle their young. Into the summer, large males continue south to Antarctic feeding grounds before turning north again in autumn.

Feeding: major food sources are oceanic squids and occasionally giant squid taken at great depths. They also eat fish such as groper and conger eels when close inshore.

Sounds: Produce clicks or sharp, broad-band pulses which can carry up to 10km under water. Can sometimes be heard by humans through the hulls of boats as a "cracking" sound similar to the noise of a dry rope chafing around a mooring bollard.

Predators: Killer whales, large sharks and man.