Fin whale

Balaenoptera physalus

Fin whale Fin whale
The Fin whale is the second largest weighing animal that ever inhabited our planet (after the Blue whale).
As for all Mysticeti, females are larger than males.
Individuals in the Southern Hemisphere are larger than their northern relatives. While the former ones are known to reach the remarkable length of 27 metres, the latter are limited to a record of 24 metres, with an average length of 22 m. It has recently been proved by genetic analysis that what we reckoned to be a single species, Balaenoptera physalus, is actually two distinct species. The second type of "Fin whale" has been named Balaenoptera omurai (Omura's Whale).
The "real" Fin whale, whose scientific name is still Balaenoptera physalus is by far the most common among the two in all seas. The body of the Fin whale is slender and highly streamlined.
Not surprisingly, it is a fast swimmer, probably the fastest among Mysticeti, and it is able to reach the striking speed of 37 km/h (over 20 knots). A very good clue to the identification of this species is the unusual asymmetry of pigmentation on its head: indeed, the right side of its lower lip is white, while the left side is uniformly gray.
Moreover, the blazes and swirling chevron markings on the dorsal region often allow to tell individuals apart. The Fin whale very rarely shows its flukes when diving, and does not breach very often. When it does breach, it typically leaves the surface at an angle of about 45° and lands on its belly. The baleens in this species rarely reach the length of 1 metre, and show the same pigmentation asymmetry observed in the lower jaw: plates are gray on the left side and white-to-yellowish on the right side. Unlike most Mysticeti, the diet of the Fin Whale is quite wide, and includes krill, fish and small cephalopods.
In the Mediterranean, where the Fin Whale appears to be the only baleen whale inhabitant, its diet is predominantly based on the krill species Meganyctiphanes norvegica. It is worth mentioning that very accurate studies carried out by Tethys Research Institute have shown that the Mediterranean Fin whale population is genetically isolated from its Atlantic counterpart.
A third population is found in the North Pacific, while in Southern Hemisphere geographic isolation (and therefore genetic isolation) seems less likely. Migrations occur in general between warm waters and relatively high latitudes, though with less predictable patterns than in most baleen whales.
The individuals found in the Sea of Cortez (Mexico) seem to be year-round residents. The Fin whale is not an easy one to follow. It is hard to predict where and when it will surface again after a deep dive.
It typically blows 4 to 8 times before diving for 5-15 minutes.
The maximum depth reached by this species was long assumed to be in the range of 230-250 metres. Tethys Research Institute has recently recorded in the Ligurian Sea (Mediterranean) diving profiles with surprising maximum depths of over 400 metres. As with the Blue whale, Fin whales started to be hunted with the advent of the exploding harpoon gun and steam or diesel powered boats.
Its conservation status is still considered as Vulnerable.