Grampus (St. Vincent) (see also p. [96]).
Description
In addition to the northern bottlenosed whale (p. [67]) and the goosebeaked whale (p. [70]), four other species of beaked whales have been reported from the western North Atlantic. All four species are known primarily from stranded specimens and have been rarely encountered at sea. Therefore statements of range are usually limited to inferences from locations of strandings, and information on appearance and habits of the species in the wild is almost totally lacking.
The infrequent encounters with beaked whales at sea may result from such factors as 1) a low inconspicuous blow, 2) avoidance of ships, and/or 3) distribution in small groups in offshore areas well outside the normal boating lanes.
The following descriptions will aid primarily in identifying stranded specimens. Though subtle differences in ranges, color patterns, and dorsal fin shapes and positions may be helpful in narrowing the choices of living animals, the species will continue to be extremely difficult to distinguish from one another in the brief encounters typical at sea until additional data are collected.
The beaked whales have the following characteristics in common: 1) two small creases forming a V-shape on the throat, 2) the absence of a conspicuous notch on the rear margin of the tail flukes (some specimens have a slight indentation), and 3) the absence of functional teeth in all except adult males. Adult males have a single pair of teeth in the lower jaw, the position and description of which help to identify the species. The teeth of females are not functional and only rarely emerge from the gums. Therefore, if a stranded animal is an adult male, its species can be determined by the position and description of the teeth. For example, in Mesoplodon mirus, the teeth are located near the tip of the lower jaw; in M. europaeus, they are located about a third of the way from the tip of the snout to the corner of the mouth; in M. bidens, they are nearly half way from the tip of the snout to corner of the mouth; and in M. densirostris, they are located in large prominences near the back of the mouth.
If the animal is a female or an immature male, however, museum preparation and examination might be required before the species can be positively determined. The following four sections summarize characters of western North Atlantic beaked whales.
