Ziphiidaebeaked whales

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The Ziphiidae includes 19 species in 6 genera. It is the second largest family of cetaceans after the Delphinidae. Its members are found in all oceans.

Ziphiids are medium-sized whales, up to around 13 m in length and 11,500 kg wt. They have distinctive, long and narrow beaks. In some species, the snout is sharply set off from the rest of the head by a bulging forehead as in members of the Delphinidae; in others, however, the profile across the forehead is relatively flat. Their flippers are relatively small and oval to gently pointed in shape. Beaked whales have a small, falcate dorsal fin, which is set fairly far back on their bodies (well beyond the midpoint). The trailing edge of the fluke has no notch, unlike other cetaceans. Ziphiids have up to six short grooves on their throats. These converge anteriorly, forming a V pattern. The body color of these whales varies among species from uniform brown or gray to having contrasting white markings.

The skulls of ziphiids have an expanded facial depression like that of delphinids, but its posterior margin is very much raised. The zygomatic arch is small and hidden from dorsal view beneath the sides of the facial depression. The rostrum is very narrow, and the palate is strongly convex. The lower jaw is V-shaped and is as wide or slightly wider than the rostrum. The mandibular symphysis is relatively short, less than 1/3 the length of the ramus. The teeth vary greatly among species in number, from 19/27 in Tasmanian beaked whales to 0/1-2 in all other genera. Males of all species have 1 or 2 large functional teeth on the lower jaw; smaller, apparently non-functional teeth are sometimes seen on upper and lower jaws of several species. The teeth of females of most species remain buried in the gums, suggesting that ziphiid teeth are used mostly in social encounters.

The ziphiids are a diverse group, but the ecological and social habits of its members are not well known. They are capable of prolonged deep dives. All feed on squid; some also include fish in their diets. The social groups, insofar as is known, consist of 3-40 individuals.

Some ziphiids are pursued by whalers for their oil and spermaceti.

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