Adult Male © Phil Coles

Quick Facts
Length 5.5-6.2m Distribution Circumpolar in the temperate waters of the southern hemisphere.
Weight 1.3 tons Identification Bold black and white markings are distinctive. Long beak. Teeth very exaggerated in adult males, swept back and rising over the top of the upper jaw.
Diet Mostly small squid. Threats ?
Group size 1-3+  

This is one of the most distinctive beaked whales, with bold black and white markings that almost rival those of the killer whale. Although the contrast between light and dark seems to vary from one individual to another they typical show the reverse of cetacean body markings being dark below and lighter above. A white cape covers the fore part of the animal, from the tip of the beak across the back as far as the dorsal fin, uninterrupted apart from a dark cap across the eyes and forehead. The markings can be clearly visible at sea.

The strap-toothed whale has one of the most unusual sets of teeth of any mammal. As with many beaked whales the teeth only erupt in adult males, but in these individuals they grow up from the lower jaw and around the upper until it is completely encircled and is prevented from opening fully. In fact mature male strap-toothed whales cannot open their jaws more than 11-13cm – not much for an animal up to which can grow to 6m in length. Maladaptive as they seam, these teeth do not appear to lead to starvation, though the diet of this species does appear to be restricted to mainly small fish and squid with an average mantle length of 13-16cm. This is one of a number of species apparently restricted to the southern ocean with most strandings being recorded from New Zealand, South Africa, Australia and South America. Sub-Antarctic prey species have been recorded from whales stranded in South Africa suggesting that some individuals at least are migratory within their Southern Ocean range.

Key references:

Sekiquchi et al (1996) The diet of the strap-toothed whale (Mesoplodon layardii) Journal of the Zoological Society of London. 239 pp 453-463

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