Bryde's Whale - Anatomy

Anatomy

The Bryde's whale is a baleen whale, more specifically a rorqual belonging to the same group as blue whales and humpback whales. It has twin blowholes with a low splashguard to the front. Like other rorquals, it has no teeth, but has two rows of baleen plates.

Bryde's whales closely resemble their close relative the sei whale. They are remarkably elongated (even more so than fin whales), with the greatest height of the body being 1/7 their total length – compared to 1/6.5 to 1/6.75 in fin whales and only 1/5.5 in sei whales. Bryde's are dark smoky gray dorsally and usually white ventrally, whereas sei whales are often a galvanized blue-gray dorsally and have a variably sized white patch on the throat, a posteriorly oriented white anchor-shaped marking between the pectoral fins, and are blue-gray beyond the anus – although Bryde's off South Africa can have a similar irregular white patch on the throat. Bryde's have a straight rostrum with three longitudinal ridges that extend from the blowholes, where the auxiliary ridges begin as depressions, to the tip of the rostrum. The sei whale, like other rorquals, has a single median ridge, as well as a slightly arched rostrum, which is accentuated at the tip. Bryde's usually have dark gray lower jaws, whereas sei whales are lighter gray. Bryde's have 250-370 pairs of short, slate gray baleen plates with long, coarse, lighter gray or white bristles that are 40 centimetres (16 in) long by 20 centimetres (7.9 in) wide, while sei whales have longer, black or dark gray baleen plates with short, curling, wool-like bristles.

The forty to seventy ventral pleats extend to or past the umbilicus, occupying about 58% and 57% of the total length, respectively – sei whales, on the other hand, have ventral pleats that extend only halfway between the pectoral fins and umbilicus, occupying only 45-47% of the total body length, whereas their umbilicus is usually 52% of the total body length. Both species are often covered with white or pink oval scars caused by bites from cookie-cutter sharks.

Bryde's have an upright, falcate dorsal fin that is up to 46.25 cm (18.5 in) in height, averages 34.4 cm (13.75 in), and is usually between 30 and 37.5 cm (12 and 15 in). It is often frayed or ragged along its rear margin and located about two-thirds the way along the back. The broad, centrally notched tail flukes never break the surface. The flippers are small and slender.