1.5 Common names English: Sperm whale

P. catodon is the largest of the toothed whales, and the only great whale in the suborder Odontoceti. It is a dark, wrinkled marine mammal featuring a massive blunt head, a round or triangular hump, a blowhole on the front left side, a keel-like white belly and large triangular flukes, with a straight trailing edge and a deep central notch. P. catodon lives to 60 or 70 years. It exhibits the highest degree of sexual dimorphism of any cetacean: males, noticeably larger in the head, attain physical maturity at 35-60 years and average 15.2-16.1m in length, while females attain sexual maturity at 25-45 years and average 10.4-11.0m in lenth. The maximum recorded weight is 57.1 tonnes (male) and 24.0 tonnes (female); the maximum recorded length is 18.3m (male) and 12.5m (female) (Bannister 1968, 1969; Rice 1989). Females are believed to remain in the same nursery groups for life – comprising 10 to 25 females, juveniles and small males. Aggregations of such groups have been reported, sometimes into the thousands (eg. in the Tasman Sea, February 1978: Paterson 1986). Medium-sized males form smaller bachelor schools of 15-21 year-olds, and remain in temperate waters. Large males, on the other hand, are solitary, and can penetrate polar seas. P. catodon are seasonal breeders, mating from late winter through early summer. The normal breedin