Blainville's beaked whale

Mesoplodon densirostris
Other names: 
  • Dense-beaked whale
Maximum length: 
  • Male: 4.7m
  • Female: 4.7m
  • Calf: 2m
Maximum weight: 
  • Male: Unknown
  • Female: 1,033 kg's
  • Calf: Unknown
Diet: 
  • Fish (Gadidae and Myctophidae)
  • Squid
Estimated population: 
Unknown
IUCN Listing: 
DD
CITES Appendix: 
II
CMS Appendix: 
Not Listed
Classification: 

Blainville's beaked whale is a comparatively easy to recognise member of the Mesoplodon genus of beaked whales due to the heavily arched posterior half of the lower jaw. Even females and calves have this distinctive 'arching' and in males, two large curved tusks erupt and extend past the upper jaw. The jawbone itself is denser than elephant ivory and for this reason the species is also known by some as the 'dense-beaked whale'.

Appearance: 

Blainville's beaked whale has a long, spindle-shaped body with a triangular dorsal fin set well back on the body. The back of both sexes is dark blue-grey and may darken further with age. The underside is paler and there are tan or grey-white blotches all over the body. They often carry scars, some of which are circular, believed to be made by the cookie-cutter shark. They also have particularly small flippers for such a large animal. Other features include a flat forehead and a long, thick beak. Their "blow" is small and projects forwards.

Behaviour: 

More information is known about Blainville's beaked whales than any other mesoplodont. They perform short dive sequences at 15 to 20 second intervals, followed by long dives of up to 54 minutes duration. On surfacing, the beak points skyward. After taking a breath, the beak is sometimes slapped on the surface and the animal may roll slightly before disappearing. Where this species is studied in the Bahamas, photographic re-sightings suggest a high level of site fidelity. Differences in occupancy patterns have also been reported within this study area, with a higher turnover of males than females in coastal waters. Blainville's beaked whales are also known to demonstrate female defence polygamy (‘harems') and sub-adults have been found in deeper, offshore waters, suggesting a dominance hierarchy.

Distribution: 

Blainville's beaked whales are widely distributed. They inhabit temperate and tropical waters of all three major oceans and like all beaked whales, Blainville's prefer the deeper waters. Around some oceanic islands however, they are found in shallower, more inshore waters than other beaked whales. They are not found in polar areas. The population size is unknown and threats to this species include naval sonar exercises, pollution, bycatch and hunting. They are classified by the IUCN as Data Deficient.

Distribution map: