Facts about sperm whale
Sperm whale tail with Kaikoura
Mountains
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.
- Newborn: length 3.5-4.5 m
- Adult: length 11-18 m
Range
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.
Population
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 (Dawson et al., 1996). In any one season there are around 85 sperm whales present here, most of which are likely to be male (Dawson et al., 1996).
Diet and foraging
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.
Life history
Females reach sexual maturity at around 9 years old and give birth roughly once every 5 years to one calf. Gestation lasts for approximately 14-16 months. Males appear to not reach full sexual maturity until their late twenties. Sperm whales are long lived and do not reach physical maturity until about 30 years old (females) and 50 years old (males).
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