Arnoux's beaked whale (Berardius arnuxii) and Baird's beaked whale (B. bairdii) are commonly called giant bottlenose whales. These are the largest of all the beaked whales, measuring about 13 metres long. The two species are very closely related, differing only slightly in anatomy. Both have two pairs of large triangular teeth at the tip of the lower jaw, earning them the additional common name of four-toothed beaked whales. Each tooth projects upward about 10 cm (4 inches).

Arnoux's beaked whale is found at middle and high latitudes of the southern oceans from Argentina, the Falkland Islands, Australia, and New Zealand southward. There is only one recorded stranding from as far north as South Africa. This species has been hunted infrequently. Baird's beaked whale inhabits a corresponding section of the northern Pacific from Japan and the Baja peninsula northward into the Sea of Okhotsk and the Bering Sea. It is still hunted off the coast of Japan.

The two species of bottlenose whale in the genus Hyperoodon have only one pair of small, conical teeth. The northern bottlenose (H. ampullatus) has an accentuated pair of crests on the skull (maxillary crests—a common feature among beaked whales, especially males). The maxillary crests of the southern bottlenose whale (H. planifrons) are more modestly developed.

The range of the southern bottlenose whale extends slightly farther north than Arnoux's beaked whale. It has often been observed near South Africa, Argentina, Uruguay, the Falkland Islands, Sri Lanka, Australia, and New Zealand and sometimes strays as far north as southern Brazil. Occasionally, whalers have taken this species.

The northern bottlenose inhabits the Atlantic Ocean from New England, Nova Scotia, northern Europe, the British Isles, and Norway northward to Greenland, Iceland, Jan Mayen island (Jan Mayen), and the limit of the pack ice in the Davis Strait. It migrates southward from the pack ice in winter, following the cuttlefish it preys upon. Usually traveling in pods of 2 to 10 or more, northern bottlenose whales will not abandon a disabled member, which makes the pod extremely vulnerable to hunters. Bottlenose oil is very similar to spermaceti and was known as “Arctic sperm oil.” It sold for a lower price and gummed more easily than sperm oil. The bottlenose whale fishery peaked in the 1890s and again in the 1960s.

Bottlenose whales belong to the beaked whale family, Ziphiidae, of the toothed whale suborder, Odontoceti. The scientific names of the giant bottlenose whales honour specific individuals. The genus name Hyperoodon, on the other hand, was based on the misidentification of rough projections on the palate as teeth (from the Greek hyperoon, referring to the roof of the mouth as an “upper room,” and odon, meaning “tooth.” The specific name ampullatus comes from the Latin ampulla (“bottle”); planifrons refers to the flat front portion of the skull.