To see photographs of Sei Whale (Balaenoptera borealis) click here.
Whale (Balaenoptera borealis)
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© 2014 Kelvin Aitken.
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Taxonomic name: Balaenoptera borealis
Other Common Names: Lesser Fin Whale.
Sei Whales (pronounced
say) belong to the Balaenopteridae or Rorqual family of whales.
Sei Whales are born at 4.5-4.8 meters and grow to 21 meters.
This speedy species of Baleen whale can be found in all oceans in polar
to warm temperate waters, usually in oceanic areas though sometimes found
near shore in deep water.
The Sei Whale (Balaenoptera borealis) is dark grey on the back with this
colour extending well down over the flanks towards the ventral surface
which has pale grey/white markings from the chin to the genital area.
All fins are dark on the ventral surface with no white markings. The long
tapered body is covered in a spotted pattern of cookie cutter shark bites
and other scars. The snout is narrower and sharper than a Blue Whale but
less pointed than the Fin with a single ridge from the twin blowholes
to the tip of the snout which also has a distinctive downward curve at
the tip visible from above and from the side. The sharply pointed dorsal
fin is strongly curved, sometimes with a boomerang shape to the leading
edge, and situated well back on the body.
Being shallow feeders Sei Whales surface at a shallow angle so that the
blowholes and dorsal fin are visible together. When they dive they almost
never show their flukes but submerge in a similar manner as their ascent,
with their shallow immersion shown by a pattern of footprints
on the surface as they move along just below the surface. They feed in
small groups of 2-5 adults on krill, copepods, squid and small schooling
fish with a skimming technique; not lunge feeding like Humpback Whales.
They are regarded as the fastest of the Rorqual whales and may be easily
confused with Brydes Whales. The most
distinctive difference between these two species is the single rostral
ridge on the Sei and the triple set of rostral ridges on the Brydes