Pygmy Sperm Whale

The Pygmy Sperm Whale is a small robust whale.

Identification

The head of the Pygmy Sperm Whale is short and supports a bulbous snout that becomes blunter with age. The snout contains the spermaceti organ. The short narrow underslung mouth is characteristic of the Family Kogiidae group and in this species contains 12 to 16 pairs of teeth in the lower jaw. The overall upper body colour is a bluish steel grey, which fades to a dull white below the head, body, flippers and flukes.

Similar species

At sea it is often difficult to separate the Pygmy Sperm Whale from the Dwarf Sperm Whale. Externally the only real difference is that the latter has a larger more prominent dorsal fin.

Distribution

Pygmy Sperm Whales are found throughout the temperate and tropical zones both in the open ocean and the continental shelf edge and slope. These are not social animals so the rare sightings at sea usually only involve single animals or a small group. They appear to be slow moving and inactive especially on the surface, a behaviour trait that probably makes them vulnerable to shark attack and collision with boats.

Feeding and diet

The Pygmy Sperm Whale's diet largely consists of a variety of squid and cuttlefish however they are also known to take shrimp, crabs and some fish. They are thought to forage over a range of ocean depths, which includes some time feeding on or near the ocean bottom.

Life history cycle

The lack of information about the Pygmy Sperm Whale's social structure makes life history data difficult to gather. Most of what is known is obtained from the many single animals or occasionally mothers with calves that strand. The gestation period is thought to be about 12 months and it appears likely that females give birth on a yearly basis.

Conservation status

Generally regarded more as a common species rather than abundant, the threat the Pygmy Sperm Whale faces is not direct hunting, although this does occur. Rather, the increasing incidence of entanglement in nets and ingestion of marine pollution such as plastic bags is the main threat.

References

• Baker, A. N. 1999. Whales and Dolphins of Australia and New Zealand: an identification guide. Allen & Unwin, St Leonards, Australia.
• Bryden, M., Marsh, H. and Shaughnessy, P. 1998. Dugongs, Whales, Dolphins and Seals. A guide to the sea mammals of Australasia. Allen & Unwin, St Leonards, Australia.
• Menkhorst, P. 2001. A Field Guide to Mammals of Australia. Oxford University Press, Melbourne, Australia.
• Reeves, R. R., Stewart, B. S., Clapham, P. J. and Powell, J. A. 2002. National Audubon Society Guide to Marine Mammals of the World. Chanticleer Press, Inc New York, USA.