Fam.: Ziphiidae Northern bottlenose whales are the largest species covered by the ASCOBANS Agreement, adult males reaching almost 10 m in length. They are named after their long tube-like snout, distinctly separated from the melon-shaped forehead. Mature bulls develop a very steep and bulging forehead with a squarish profile and a nearly white colour. As is characteristic for most beaked whale species (Ziphiidae), the teeth of bottlenose whales are reduced, and two conical teeth at the tip of the lower jaw erupt only in adult bulls.

The species is endemic in the cold temperate to sub-Arctic North Atlantic and prefers deep offshore waters, mostly seaward of the continental slope. Northern bottlenose whales are excellent deep divers and can stay submerged for more than an hour. They feed primarily on squid, but also take fish and bottom-living invertebrates.

At least three additional beaked whale species (Ziphiidae) have been occasionally reported from the North Sea. Cuvier's beaked whale Ziphius cavirostris, Sowerby's beaked whale Mesoplodon bidens and True's beaked whale Mesoplodon mirus are also oceanic, deep-diving species with reduced teeth that feed primarily on squid.

Illustrations: M. Camm