Boschung, Herbert T. Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama.
Last reviewed:July 2015
Show previous versions
- Chlamydoselachidae (frill sharks)
- Hexanchidae (cow sharks)
- Related Primary Literature
- Additional Reading
An order of squalomorph sharks commonly known as the six- or seven-gill sharks. The order Hexanchiformes comprises two extant families (Chlamydoselachidae, the frill sharks; and Hexanchidae, the cow sharks), four genera, and six species. These sharks are distinguished by a combination of the following characters: six or seven gill slits, all anterior to the pectoral fins; a single dorsal fin without a spine; anal fin present (the only order of squalomorphs with an anal fin); the dorsal, anal, and pelvic fins placed far posteriorly; eyes lacking a nictitating fold or membrane (at the inner angle of the eye or below the eyelid and capable of extending over the eyeball); spiracles present, but small and well behind the eyes; and ovoviviparous development. See also: Elasmobranchii; Selachii
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 45 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information