San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide

Balaenoptera physalus
Finback Whale, Razorback Whale, Common Rorqual

BALAENOPTERIDAE (Rorqual Family)

Description

The finback whale is probably the most common baleen whale seen in summer off the Pacific coast. Its V-shaped head is small, compared with other whales, and the top of the head is flat with paired blowholes. The whale is either dark gray or brownish gray above, and white underneath, including the lower surface of the tail and flukes. The pigmentation of the head is unique in its asymmetry: the left lips are dark while the right lower lip, including the right baleen plates and tongue, and occasionally the right upper lip are yellowish white. A small sickle-shaped dorsal fin is present, usually far down the back. This fin is one of the whale's most obvious characteristics and is easily seen at sea. There are ridges along the back, between the dorsal fin and the tail. The baleen plates are relatively short, purple and white or lead-colored. There are 50-86 deep throat grooves.

Size: Finback whales average 21 meters (70 feet) in length, with some reaching up to 24.3 meters (80 feet). The average weight is 45,000 kg (40-50 tons).

Range and Habitat

In the Pacific, the finback whale is found from the Bering Sea to Cabo San Lucas, Baja California Sur. In the Atlantic, its range extends from the Arctic Circle to the Greater Antilles, including the Gulf of Mexico. Finback whales frequent inshore and offshore waters.

Natural History

Behavior: Finback whales travel in groups of a few individuals to several hundred whales. When it spouts, the spray is shaped like an inverted cone, and can shoot up 4.5-6 meters (15-20 feet) high. The spout is accompanied by a loud whistling sound. When diving, the whale arches its back slightly, but doesn't expose its flukes.

Diet: The finback whale feeds on small schooling fishes, pelagic crustaceans, and squids.

Conservation Status

The finback whale was listed as endangered in 1970. The current status of this species is unknown, following severe depletion by commercial whaling in the last century. The present world population is about 120,000 individuals.


Text: Linda West in consultation with Dr. Thomas Deméré

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