Beaked whales are members of the sub-order odontoceti, or toothed whales, and the family Ziphiidae. There are currently 22 documented species of beaked whale, making it the largest family of toothed whales (Bianucci et al., 2008). Relatively little is known about beaked whales as majority of information on them was gained from beached carcasses, and it is only more recently that any other form of data has become available.
The Cuvier’s beaked whale (Ziphius cavirostris) is the most widely distributed and most commonly spotted of the beaked whale family, and holds the record for diving to the deepest depths of any known mammal (Schorr et al., 2014). They occur in groups of between 1 and 5 individuals, and are thought to dive in groups (Baumann-Pickering et al., 2014). It is a pelagic species, however they frequent depths in excess of 1000m, with the deepest dive recorded of 2992m and lasting 137.5 minutes, which is also the longest recorded mammalian dive length (Schorr et al., 2014). At this depth these whales are subject to pressure of approximately 300 atmospheres and, being air breathing animals, they must travel to and from the surface in order to breathe and so undergo humongous changes in pressure. This extreme life strategy requires highly specialised morphology and behaviour, and also makes study of these creatures highly challenging as they spend very little time at the surface, are capable of traveling vast distances and generally avoid boats (McSweeney et al., 2007; Schorr et al., 2014).
For a long time it was thought that the Cuvier’s beaked whale was an extinct species after naturalist Georges Cuvier examined a skull fragment found in 1804. In 1823 his paper “Recherches sur les ossemens fossiles” was published describing the fragment, however mistaking it to be petrified remains. It wasn’t until 1850, when the supposed fossilised bone was found to match the skull of a whale carcass found on shore, that it was discovered that Cuvier’s beaked whale was not only not extinct, but of relatively high abundance. It was named after and speculated to be the animal behind the Ziphius, a medieval sea monster of folklore that was said to have the body of a fish with the head of an owl, and large sword-like fins that pierced the hulls of ships.