Species fact file
Common names: Blainville’s beaked whale, dense-beaked whale
Icelandic name: króksnjáldri
Scientific name: Mesoplodon densirostris
Family: Ziphiidae (beaked whales)
Max length: 4.7m (females typically larger than males)
Distribution: tropical and temperate waters globally
Blainville’s beaked whale is the most widely distributed species of its genus, the mesoplodont whales. They are found in tropical and temperate seas around the world. Although there are a few records of Blainville’s beaked whale in Iceland, it is very rare for this species to come so far north, and all of these records are of stranded whales.
As a deep diver, Blainville’s beaked whale is found mainly in the open ocean over the continental slope in waters between 200 and 1000m deep. However, they can be seen close to shore around oceanic archipelagos such as the Canary Islands, Bahamas, and Hawai’i.
This species was first described in 1817 by French zoologist Henri de Blainville from a small piece of jawbone. The bones of the beak and jaw are the densest of any animal, which is where the name ‘dense-beaked whale’ comes from. They have a very distinctive arched lower jaw which is especially pronounced in males. Like all beaked whales, females don’t have any teeth and males have just one pair: at the apex of the arch, jutting up above the top of their head. These tusks often become a home for purple stalked barnacles.
Blainville’s beaked whales do not need their teeth for hunting as they are suction feeders, like other beaked whales – males only use their tusks in competitions with other males for access to females. They are able to create a pocket of low pressure in their mouth by retracting their tongue and expanding special grooves in their throats. This vacuum sucks their prey straight into their mouth, bypassing the need for teeth to grab it with.
Studying the diet of Blainville’s beaked whale is difficult since they feed deep underwater, but stomach contents from stranded whales can give us some idea of what they eat. Typical of beaked whales, it seems this species feeds mainly on deep-water squids and fishes as well as some crustaceans.
Blainville’s beaked whales have strong site fidelity and return to the same regions regularly. This has allowed some long-term photo ID studies in the archipelagos where they can be encountered close to shore. Social groups can consist of between 3 and 7 individuals, but 4 is the average group size. There are some differences in how males and females socialise. Males tend to be found alone or in small groups, whereas females and calves prefer larger groups with several adult females. These large groups may occasionally include a male, but only one.
Killer whales are one of the most significant predators of Blainville’s beaked whales. It is likely that females prefer to stay in large groups as this provides some kind of protection for their smaller calves, which would be vulnerable to attack from killer whales.
Blainville’s beaked whales stay silent up to 80% of the time – this is most likely another defense against killer whales. They communicate with one another while hunting in deep water but stop vocalising once they start their ascent. Killer whales are relatively shallow divers compared to beaked whales, so they are only at risk in the first 100-200m of water: staying silent at these depths means they can avoid being overheard by these deadly predators.
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