Balaenidaebowhead whales and right whales
This is a mysticete family of two genera and three species. They are found near in most waters of the temperate and polar regions.
Right and bowhead whales are large whales, reaching up to 18 m in length and over 100,000 kg weight. Their heads are huge, nearly 1/3 of their total length. The dorsal fin is either lacking. Flippers are short and rounded. The throats of balaenids are smooth, lacking the furrows or grooves of some other mysticetes.
The skull of balaenids has reduced nasals, and the frontals are barely exposed on the dorsal surface. The posterior border of the nasals and premaxillae lie anterior to the supraorbital processes of the frontals. The rostrum is high, narrow, and arched. Baleen plates are long and narrow, and they number more than 350 on each side of the upper jaw. The right and left baleen rows are separated in the front of the mouth.
Right whales feed largely on copepods, which they catch by swimming slowly, with their mouths open, through concentrations of these crustaceans. Water flows into the huge mouth and out between the baleen plates. Food is trapped on the fringes of the plates and scraped off with the tongue. They normally feed at or near the surface.
These whales live singly or in small groups of up to 3 or 4 individuals. Their stocks were severely depleted by whaling, and they remain low. The name "right whale" is said to have originated because these were the "right" whales for whalers to kill.
References and literature cited:
Nowak, R.M. and J.L. Paradiso. 1983. Walker's Mammals of the World, 4th edition . John Hopkins University Press, Baltimore, MD.
Savage, R. J. G. and M. R. Long. 1986. Mammal Evolution: An Illustrated Guide. Facts on File Publications, UK. 251 pp.
Rice, D. W. 1984. Cetaceans. Pp. 447-490 in Anderson, S. and J. K. Jones, Jr. (eds). Orders and Families of Recent Mammals of the World. John Wiley and Sons, N.Y. xii+686 pp.
Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, N.Y. vii+576 pp.
Wilson, D. E., and D. M. Reeder. 1993. Mammal Species of the World, A Taxonomic and Geographic Reference. 2nd edition. Smithsonian Institution Press, Washington. xviii+1206 pp.
Contributors
Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.
Glossary
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- chemical
-
uses smells or other chemicals to communicate
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- motile
-
having the capacity to move from one place to another.
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- tactile
-
uses touch to communicate