The finback whale, Balaenoptera physalus, also known as the fin whale, is a member of the baleen whale family. The fin whale is the world's second largest whale species after the blue whale. The fin whale is also the fastest whale in the world, and can move at speeds up to 23 mph (approximately 37 km/hr).
There are two distinct families of fin whale; one lives in the Northern Hemisphere, and one lives in the Southern Hemisphere. While females throughout the species are slightly larger than the males, there also is a size difference between the two families. Generally, the fin whale averages from 75 feet to 78 feet (23 m to 24 m) in the Northern Hemisphere and from 85 feet to 88 feet (26 m to 27 m) in the Southern Hemisphere. The fin whale can weigh anywhere from 50 tons to 70 tons (43 tonnes to 63.5 tonnes), and eats nearly 2 tons (1.8 tonnes) of food daily. Fin whales consume krill, a shrimp-like creature, along with other small fish and squid.
The commonality among species in the baleen whale family is that the whales don't have teeth. Instead, they have what are known as plates. These plates are made of the same substance as human fingernails.
Unique to the fin whale is its asymmetrically colored head. One side is a cream color, while the other is black, and the pattern is reversed on the whale's tongue. It is thought that the reason for the unique head coloration could have something to do with their feeding habits. Fin whales generally use their speed to circle their prey, essentially squeezing the schools of fish and krill into a ball. The whale then opens its baleen plates, ingests its prey along with a large amount of water, and filters out — using little hairs in the plates — the food from the water.
Fin whales generally live in groups of three to seven, and prefer living in cooler oceans over tropical areas, though they migrate to warmer regions in the winter months. This is often so a female can give birth before migrating back to cooler waters after carrying her baby for about a year. Fin whales can live anywhere from 80 to 90 years.
While fin whales were once too fast for whalers to catch and kill, technology has made them easy prey for whalers. After the blue whale population started to thin out, whalers began hunting fin whales. This has resulted in their listing as an endangered species.