Snubfin dolphin

Snubfin Dolphin Illustration by E. Hawkins

Scientific name: Orcaella heinsohni

Physical Features

  • Length: Adult male: 2.7m; female: 2.3m (males are generally larger- sexual dimorphism)
  • Weight: Adult male: 133kg; female: 114kg
  • Colouration: Australian snubfin dolphins have three-tone colouration. They have a dark brown dorsal cape, light brown lateral sides and a white underbelly.
  • Teeth: peg-like, conical, less than 20 on each side
  • Dorsal fin: small ‘snubby’ dorsal fin, on the latter half of the body
  • Distinct feature: rounded head with no beak, mobile neck, pectoral fins (flippers) are broad and paddle-like

Biology & Ecology

 Formally known as Irrawaddy dolphin the Australian snubfin dolphins were recognized as a genetically separate species in 2005. Little information is known about them.

  • Eat: generalist feeders, diet primarily consists of fish, squid, cuttlefish, octopus and shrimp
  • Submerged: they can hold their breath for up to 12 minutes
  • Maturity: Still unknown
  • Life expectancy: Still unknown
  • Breeding season: Calves are seen all year round
  • Habitat: found in Broome (Western Australia) to Fitzroy River (Queensland); primarily in coastal and shallow waters, often near river mouths; generally have small home ranges

Behaviour & Social Organisation

  • Group size: live in small populations, maximum of 15 animals
  • Social:
  • Behaviour: can be seen partially jumping, never observed leaping clear of the water; Low surface profile; shy, inconspicuous and generally unpredictable
  • Unique behaviour: individuals have been seen spitting jets of water ahead of its prey, possibly to disorientate.

Acoustic Communication

A study conducted by Van Parijs et al (2000)  on the coastal waters of Northern Australia recorded various noises, with sounds similar to broadband clicks, pulses and whistles. During foraging the dolphins were described to make creaking and buzzing noises as well as broadband clicks. Whistling was recorded during socialization and foraging.

Conservation Status

  • ‘Near threatened’ in the Queensland Nature Conservation Act 1992
  • ‘Migratory’ under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999

 

References

Van Parijs, Sofie M., Guido J. Parra, and Peter J. Corkeron. “Sounds Produced By Australian Irrawaddy Dolphins, Orcaella Brevirostris”. The Journal of the Acoustical Society of America 108.4 (2000): 1938-1940. Web.