Perrin's beaked whale
This species has only been found off the coast of California between San Diego and Monterey. It likely lives offshore the Pacific coast of North America - and possibly elsewhere in the North Pacific.
Perrin's beaked whales cannot be identified with absolute certainty at sea. However, the combination of small size, appearance and presumed range makes a confusion unlikely. Stranded specimens can be identified as this species by either DNA sequence data and/or anatomical details of the skull.(Dalebout et al. 2002)
This species has a fairly typical body shape for a mesoplodont, with a small head, long body, and deep tail. The rostrum of this whale is shorter than every other mesoplodont other than Hector's and the pygmy beaked whales, especially in young individuals. The mouthline of this species is straight, and the melon forms a small bulge with a crescent-shaped blowholewith forward-pointing tips. The teeth on this species are fairly large and towards the tip of the mouth. Throat grooves are present on this species.
The coloration is dark gray above and white below in the holotype male, with a lighter gray underside of the tail fluke. A white patch is present near the navel. The colouration of females is not known, since the only specimen was rather decomposed.
The mature male specimen was 3.9 metres in length (13 feet) and the female was 4.4 metres (14 feet 8 inches) in length; the immature males measured between 2.1 and 2.45 metres (7-7.5 ft).
Few stomach contents were available for analysis. Presumably, this species eats pelagic squid (such as Octopoteuthis deletron, remains of which were found in the female's stomach) and possibly small fish like other beaked whales.
The largest immature LACM 088901, at 2.45 metres of length, was apparently independent from its mother. On the other hand, the smallest known specimen, USNM 504259, had a fringed tongue which indicated it was still suckling. Teeth were not present in the immatures, but they are not needed for feeding. The dates when the specimens were found suggest the young start to feed independently in summer; considering most whales suckle until around one year of age, this suggests the young are born during the summer half of the year. Consequently, as they are all of somewhat similar size, the immatures were probably around one year old. The adults were both an estimated 9 years old when they died.
Nothing is known of this species' behavior in life. However, as this is apparently quite similar in all Mesoplodon, a number of well-founded assumptions can be made.
The males of this species seem to engage in fights like most other mesoplodonts. Scars from fighting are present on this species, although the precise mechanism of combat is enigmatic: given the teeth's position near the lower jaw tips, it can be expected that the scars consist of two parallel lines; only single scar lines were present on the adult male, however, suggesting glancing blows rather than direct attacks created them.