How deep can a dolphin dive?

The deepest dive ever recorded for a bottlenose dolphin was a 300 meters (990 feet). This was accomplished by Tuffy, a dolphin trained by the US Navy. Most likely dolphins do not dive very deep, though. Many bottlenose dolphins live in fairly shallow water. In the Sarasota Bay area, the dolphins spend a considarable time in waters that are less than 2 meters (7 feet) deep.

Other whale and dolphin species are able to dive to much greater depths even. The pilot whale (Globicephala melaena) can dive to at least 600 meters (2000 feet) and a sperm whale (Physeter macrocephalus) has been found entangled in a cable at more that 900 meters (500 fathoms) depth.

Recent studies on the behavior of belugas (Delphinapterus leucas) has revealed that they regularly dive to depths of 800 meters. The deepest dive recorded of a beluga was to 1250 meters. [1]

Do dolphins drink salt water?

Most dolphins live in the ocean and the ocean water is too salty for them to drink! If they would drink sea water, they would actually use more water trying to get rid of the salt than they drank in the first place. Most of their water comes from their food (fish and squid). Also, when they metabolize (burn) their fat, water is released in the process. Their kidneys are also adapted to retaining as much water as possible. Although they live in water, they live as desert animals with no direct source of drinkable water.

more (part 3) ...

Adapted from Dolphin FAQ maintained by Jaap van der Toorn (jaap@compuserve.com)

sources:
[1] F.G. Wood (1993) Marine mammals and man. R.B. Luce, Inc., Washington. E.J. Slijper (1979) Whales, 2nd edition. Cornell University Press, Ithaca, NY. (Revised re-issue of the 1958 publication: Walvissen, D.B. Centen, Amsterdam).

[1] R.S. Wells, A.B. Irvine and M.D. Scott (1980) The social ecology of inshore odontocetes. In: L.M. Herman (ed.): Cetacean Behavior. Mechanisms & functions, pp. 263-317. John Wiley & Sons, New York

[1] A.R. Martin (1996) Using satellite telemetry to aid the conservation and wise management of beluga (Delphinapterus leucas) populations subject to hunting. Paper presented at the 10th Annual Conference of the European Cetacean Society, March 11-13, 1996, Lisbon, Portugal.