Earthsky FAQs
Private: Shark Electroreception
Some sharks migrate across thousand of kilometers of open ocean. Scientists think they map their journey using a sense humans don't have -- guided by Earth's magnetic field. Learn more about electroreception -- on today's Earth and Sky.
04-10-2002 - Biodiversity
_DB:_ One shark sense – called “electroreception” – is the ability to detect weak electric fields. Sharks do this by means of special, very sensitive electroreceptor cells – found in clusters on a shark’s head and snout.
_JB:_ Bottom feeding sharks can detect the faint electrical fields surrounding living animals – even when the prey is buried in the sand. The unusual shape of the hammerhead shark’s head may be an adaptation to spread their electroreceptors over a wider area for better searching.
_DB:_ Electroreception might help sharks migrate hundreds, sometimes thousands, of kilometers of open ocean. In other words, while migrating, sharks might use this sense to orient themselves to Earth’s magnetic field. Scientists don’t completely understand how this works. It’s possible that – though sharks can’t detect the magnetic field directly – they can detect its effect on themselves and objects around them.
_JB:_ By the way, if you want more about shark conservation, we’ve got web links for you. Come to today’s show at our website at earthsky.org. Special thanks today to the “National Fish and Wildlife Foundation”:http://www.nfwf.org/ and to the “U.S. Forest Service”:http://www.fs.fed.us/. I’m Joel Block with Deborah Byrd for Earth and Sky.
The following individuals were interviewed for today’s show. Our thanks to:
Lisa Jones
Research Fisheries Biologist
NOAA NMFS Research Surveys
Southeast Fisheries Science Center
Pascagoula Laboratory
Pascagoula, MS
Robert Hueter
director of the Center of Shark Research Mote Marine Laboratory
Sarasota, FL
Stephen M. Kajiura
Hawaii Institute of Marine Biology
University of Hawaii at Manoa
Diane R. Nelson
Department of Biological Sciences
East Tennessee State University
Johnson City, TN
Web sites with information on sharks and shark conservation:
“The Center for Shark Research at Mote Marine Laboratory”:www.mote.org – dedicated to the scientific study of sharks, skates and rays.
“Pelagic Shark Research Foundation”:http://www.pelagic.org/ – provides information about sharks, including images, a guide to the evolution and biology of sharks, conservation information, videos of shark encounters, and other resources.
“Discovery Online – Shark Realities”:http://www.encarta.msn.com/teleport/partners/discovery.asp?URL=http%3A%2F%2Fww. The Discovery Channel presents this site about sharks, including a 360-degree view of the inside of a shark tank, profiles of different species, a discussion forum, and many other resources.
“Australian Museum Online: Sharks”:http://www.austmus.gov.au/is/sand/sharks.htm – provides information about the life cycle, habits, and conservation of sharks.
“Nature: The Secret World of Sharks and Rays”:http://www.wnet.org/nature/sharks/ – The Public Broadcasting Service presents a feature on sharks and rays, including links to related Web resources, and a list of recommended books.
NOVA Online presents an “exhibit about sharks”:http://www.pbs.org/wgbh/nova/sharkattack/, including information about the shark’s sensory system, an overview of the natural history and life cycle of the shark, and links to related Web resources.
“The Florida Museum of Natural History”:http://www.flmnh.ufl.edu
Author’s Notes:
As a shark moves through Earth’s magnetic field, it’s thought to induce an electric field around itself that its electroreceptors may be able to detect. When the shark swims from west to east, the electric field flows in one direction through its body, when it swims east to west it flows the opposite way. Sharks may use this same mechanism to detect and orient to local “landmarks” on the seafloor.