The fin whale is the second largest living animal, second in size only to the blue whale. This large baleen whale belongs to the rorqual family, also called balaenopterid family.
Fin whales sighted during an aerial survey off West Greenland. Photo: L. Witting
19-21 m long, 45-75 tonnes in the Northern Hemisphere. Females are larger.
One calf every 2-3 years from 7-12 years of age.
Up to 85-90 years.
Between high-latitude feeding grounds in summer and lower-latitude breeding grounds in winter (most populations).
Lunge-gulping' on copepods, krill and small pelagic fish.
Latin: Balaenoptera physalus (Linnaeus, 1758)
English: Common rorqual, finback, fin-backed whale, finner, herring whale, razorback
French: Rorqual commun, baleine à nageoires, baleine fine, baleinoptère commune
Spanish: Ballena aleta, ballena boba, rorcual común
Fin whales are the most streamlined in appearance of all the rorquals and the distinct ridge along the back behind the dorsal fin gives them the nickname "razorback" (Leatherwood and Reeves 1983).
Fin whale off Greenland. Photo: F. Ugarte
Fin whale blows are tall and impressive and can often be seen at a great distance. They reach six metres in height, shaped like a slim inverse cone. Fin whales are sleek, fast swimmers. Their exceptionally large size, streamlined appearance and the small falcate dorsal fin appearing just after the blow are probably the best identifying feature.
The ultimate identification is the asymmetrical head coloration, in particular for distinguishing a fin from a sei whale.
Fin whale head with asymmetrical coloration. Photo: Marine Research Institute, Iceland
Click here to see fin whales swimming off Svalbard, Norway, and Youghal, Ireland.
Males and females are very similar in their general appearance, but females are slightly longer than males. Adult males average 19 m and adult females 20.5 m in the Northern Hemisphere, while they are slightly longer in the south, averaging about 21 and 22.3 m respectively. Adult fin whales weigh between 45 and 75 tonnes, depending on the time of year and their individual body condition.
Fin whales have a falcate dorsal fin, about 60 cm high, set about two-thirds back along the body. The jaw is large and when the mouth is closed the lower jaw protrudes slightly beyond the tip of the snout. The flukes show a slightly concave trailing edges, but they are rarely raised out of the water.
Fin whales are dark grey to brownish black in colour along the top of the body, while the throat, belly and undersides of the flippers and tail flukes are white. Some fin whales have a pale grey chevron on each side behind the head and there may be a dark stripe running up and back from the eye, and a light stripe arching down to where the flipper joins the body.
The head has a single medial ridge and is asymmetrically pigmented, with the ventral white colouration extending up over the right lower lip and inside the mouth cavity and the baleen plate. The left side of the jaw is quite dark in contrast. The asymmetrical coloration pattern on the head is reversed on the tongue. Why fin whales have this asymmetrical pigmentation, rare among mammals, is not known, although it has been speculated that it may have something to do with their feeding strategy.
As other rorquals, the fin whale bears ventral grooves along the ventral side of the body. In this species there are 55 to 100 running from the underside of the lower jaw to beyond the navel.
A series of 260-475 baleen plates hang on each side of the upper jaw. They measure up to 90 cm in length and 30 cm in width at the base. The baleens on the left side of the mouth have alternating bands of creamy-yellow and blue-grey colour. On the right side, the forward 1/3 section of the plates is all creamy-yellow.
Fin whale off Norway during a sightings survey in 2014. Photo: K.A. Fagerheim, Institute of Marine Research, Norway