Geoscience Reference
In-Depth Information
lingly white bodies “porpoised” out of the water in unison, and their bulbous heads spy-hopped above the
river's blue waters. This pod of adults and accompanying young constituted a significant portion of the world's
most southerly population of belugas, which are primarily an Arctic species.
Belugas belong to the suborder of toothed whales, the Odontoceti, and their closest relative is the narwhal.
Beluga means “the white one” in Russian, and their whiteness marks them as an Arctic species, like many oth-
er northern mammals and birds, including greater snow geese. They are well suited to Arctic conditions, hav-
ing a thick skin and blubber layer to insulate them from the cold, and lacking a dorsal fin, which may be an ad-
aptation to swimming around and under ice.
Besides their creamy white coloring, belugas have other distinctive anatomical and behavioral characterist-
ics. They have a noticeable constriction behind the head, which can best be described as a “neck.” Because the
neck vertebrae are not fused together, belugas, alone among whales, have an unusual degree of lateral head
movement. They have a bulbous forehead— the “melon”—whose shape can be changed by muscular contrac-
tions and is thought to act as an acoustic lens, enabling belugas to focus their echolocation clicks directionally.
This sonar capability helps them navigate in shallow waters and find prey, especially in dark and turbid envir-
onments such as the St. Lawrence estuary. Belugas have a narrow transmitted-beam pattern that is useful for
navigating under ice and finding air pockets under an ice pack, which seem to be adaptations to an Arctic
acoustic environment.
Belugas have been described as the noisiest of whales, earning them the sobriquet “sea canaries.” Record-
ings of their vocalizations made in the Saguenay Fiord were described as “high pitched resonant whistles and
squeals, varied with ticking and clucking sounds, slightly reminiscent of a string orchestra tuning up, as well as
mewing and occasional chirps.” Finally, belugas have a pair of flexible lips that aid in the consumption of
bottom-dwelling organisms such as flounder, eels, and crustaceans, but, to the anthropocentric-minded, lend a
smiling expression to their faces. Mostly, however, they feed on small schooling fishes, such as sand lance,
capelin, herring, and smelt, that frequent the estuary.
