Balaenopteridae: Rorqual Whales
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With the exception of the humpback whale, rorquals share some specific characteristics such as a small head, long, slender body with small flippers on the side and a small dorsal fin on the back of the body. The underside of the body is lighter than the gray or blue top side of the body and the throat area consists of a series of folded skin. The name rorqual refers to the folds, and they allow the throat to expand as the whales take in water to catch food.
Rorquals are the most abundant and widely distributed whale species, being found in all seas, except the extreme Arctic and Antarctic regions.
Generally Balaenopteridae divides into two genera, Balaenoptera (rorquals), which consist of:
- Blue Whale (Balaenoptera musculus): please use the link in the box for further information
- Byrde's Whale (Balaenoptera edeni): Scientists are currently using DNA analysis to determine the number of Bryde's species, perhaps as many as four. Balaenoptera edeni, the typical Bryde's measures around 40-50 feet in length, with populations in the Atlantic, Indian and Pacific Oceans. Their United States range is limited to the Gulf of Mexico and Southern California. The IUCN currently lists them under the least concern category (although it could change if species differentiation is recognized).
- Fin Whale (Balaenoptera physalus): Second only to the blue whale in size, the fin whale can grow to 70 feet in length. Scientists are currently unsure of the number of fin whale species, although they hypothesize there is a smaller or pygmy fin species. Population levels are considered in terms of geographical areas, with distinct populations identified in the North Atlantic, Mediterranean, North Pacific, Gulf of California, East China Sea and Southern Hemisphere. The IUCN lists them as endangered.
- Minke Whale (Balaenoptera acutorostrata) of the North and (Balaenoptera bonaerensis) of the South: Minkes are the smallest rorquals, measuring between 25-35 feet in length.
- Sei Whale (Balaenoptera borealis): The medium sized sei whale (reaching seventy feet in length) was the last of the larger whales to be hunted for commercial reasons. Like the Blue, Fin and Humpback Whales, their populations decreased dramatically in their Atlantic, Indian and Pacific Ocean ranges. While currently population estimates are uncertain, the IUCN lists them as endangered.
and Megaptera or Humpback Whale.
Japanese scientific whaling activities focus heavily on this family, hunting fin, minke whales, sei whales and Byrd's whales in both the Southern Ocean and the North Pacific Ocean.
© 2009. Patricia A. Michaels