The Blue Whale has a long tapering body that appears stretched
in comparison with the stockier build of other whales.
The head is flat and U-shaped and has a prominent ridge running
from the blowhole to the top of the upper lip.The front part of the mouth
is thick with baleen plates; around 300 plates hang from the upper jaw, running
back into the mouth. Between 60 and 90 grooves (called ventral pleats)
run along the throat parallel to the body. These pleats assist with evacuating
water from the mouth after lunge feeding (see feeding below).

The dorsal fin is small, visible only briefly during the dive sequence.
Located around three-quarters of the way along the length of the body,
it varies in shape from one individual to another; some only have a barely
perceptible lump, but others may have prominent and falcate dorsals.
When surfacing to breathe, the Blue Whale raises its shoulder and blowhole
out of the water to a greater extent than other large whales such as the Fin
or Sei. This trait may be used by observers to differentiate between species at
sea. Some Blue Whales in the North Atlantic and North Pacific raise their tail
fluke when diving. When breathing, the whale emits a spectacular vertical
single-column blow that can be seen from a great distance on a calm day.

Facts