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Whales and dolphins can be found in almost every sea and ocean, from the Arctic ocean, through the tropics all the way to the Antarctic. Each species however has its own preferred type of habitat. Some live cold water only, others in tropical oceans only. There are also species that can be found in a large variety of environments, like the bottlenose dolphins, killer whales and sperm whales. source: P.G.H.Evans (1987) The Natural History of Whales and Dolphins. Christopher Helm Publishers, London.
There are a number of dolphin species that live in fresh water. They all belong to the river dolphin families. These are: the Platanistidae (Ganges and Indus river dolphins), the Iniidae (the boto or Amazon river dolphin) and the Pontoporiidae (the baiji and the franciscana). There is one species that can be found both in fresh water (the Amazon river) and in coastal sea waters: the tucuxi (Sotalia fluviatilis). In general, salt water species don't do well in fresh water. They can survive for some time, but they will be come exhausted (since they have less buoyancy in fresh water) and after a while their skin will start to slough (like our own skin after spending a long time in the bathtub). source: P.G.H.Evans (1987) The Natural History of Whales and Dolphins. Christopher Helm Publishers, London.
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 they get from their food (fish and squid). Also, when they metabolise (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 have live as desert animals, since they have no direct source of drinkable water.
How are whales classified?
Whales are mammals. They are warm blooded, breath air through lungs
and give birth to live young that are suckled on milk secreted from
the
mother's mammary glands. Many of the features we associate with other
mammals have been modified or lost during the long process of evolution
from land dwelling ancestors and they have become superbly adapted
to life in oceans, seas and rivers.
Whales, dolphins and porpoises, collectively known as 'cetaceans' (Order Cetacea) are divided into two groups, the toothed whales or odontocetes (suborder Odontoceti) and the baleen whales or mysticetes (suborder Mysteceti). The toothed whales (around 72 species worldwide at present) generally feed on larger food items such as fish or squid and include groups such as the river dolphins, dolphins, porpoises, beluga, narwhal, Sperm Whale, pygmy sperm whales and beaked whales. The baleen whales (around 13 species worldwide) feed by filtering seawater to trap food such as planktonic invertebrates (e.g. krill), copepods, amphipods and small fish in the baleen plates attached to their upper jaws. They differ from the toothed whales in generally being larger, having baleen instead of teeth and having paired nostrils. The mysteceti include species such as the Gray Whale, Right Whales, Pygmy Right Whale and the 'rorquals' (a group that includes the Blue, Fin, minkes, Sei, Bryde's and Humpback Whales).
What is the difference between a whale, dolphin and porpoise?
The terms dolphin, porpoise and whale are confusing and do not relate
well to the scientific classification of cetaceans. In general, whales
are the largest cetaceans followed by dolphins and then porpoises.
However, some 'whales' such as the Pilot Whale and Killer Whales
are classified in the same family as dolphins (Family Delphinidae).
The
term 'porpoise' is sometimes used to refer to dolphins although it
is now generally agreed that porpoise refers to toothed cetaceans
with spade-like teeth and no beak belonging to the Family Phocoenidae
(includes
six species, one of which occurs in Australia).
How many cetacean species are there in Australia and where can I get information about them?
At present there are around 44 species recorded from Australia, 35
of these are toothed whales and 9 are baleen whales. Of the toothed
whales,
19 species are from the family Delphinidae (including dolphins, pilot
whales and killer whales) and 12 are from the family Ziphiidae (beaked
whales). Also included are the Pygmy Sperm Whale, Dwarf Sperm Whale,
Sperm Whale and Spectacled Porpoise. The baleen whales include the
Southern Right Whale, Pygmy Right Whale and seven species of rorquals
(a group
characterised by the presence of long folds of skin behind and below
the mouth).The number of cetacean species recognised worldwide and
in Australia is constantly changing as the results of ongoing morphological
and molecular studies become available.
The most up to date account of cetaceans recorded from Australia is in A Field Guide to the Mammals of Australia by Peter Menkhorst. Other useful guides include Whales and Dolphins of New Zealand and Australia by Alan Baker and Dugongs, whales and seals, a guide to the sea mammals of Australasia by Bryden, Marsh and Shaugnessy. Guides covering species found in other parts of the world as well as Australia are the Eyewitness Handbook Whales, Dolphins and Porpoises, the visual guide to all the world's cetaceans by Mark Carwardine, the Reader's Digest Whales, Dolphins and Porpoises by Carwardine, Hoyt, Fordyce and Gill and National Audubon Society Guide to Marine Mammals of the World.
DO MARINE MAMMALS GET STRESSED?
Wild animals live daily with many challenges to their survival. Predators,
hunger, noise, parasites, and environmental pollution are just a
few of the challenges animals in the wild must contend with every
day.
Animals in Alliance member facilities live without the stress of
these considerable daily challenges.
The U.S. government reports that it “is unaware of any valid scientific research or other information that documents or supports that [shows or] performances...cause additional unnecessary stress for the animals."
Additionally, a recent scientific study of steroid hormones produced by the adrenal cortex, a common measure of stress in animals, demonstrates that stress is not an issue in marine mammals in in-water interactive programs. This Dolphin Quest/Sea World study was submitted to the U.S. government in September of 2000 and provides clear evidence that the animals are in a healthy environment.
The results of behavioral and medical evaluations of animals in public display facilities indicate the animals breed very successfully, form social groupings, eat well and exhibit the same behaviors they do in the wild. In addition, symptoms commonly referred to as stress indicators, such as ulcers, are more common in wild animals that have been found stranded than in animals in responsible public display facilities.
ARE PEOPLE LEARNING ABOUT MARINE MAMMALS FROM ZOOS AND AQUARIUMS?
In an online poll released in 2005 by the Alliance of Marine Mammal Parks
and Aquariums and conducted by Harris Interactive®, 97 percent of
respondents agree that marine life parks, aquariums and zoos play an
important role in educating the public about marine mammals they might
not otherwise have the chance to see. In addition, 96 percent agree that
marine life parks, aquariums and zoos provide people with valuable information
about the importance of oceans, waters and the animals that live there.
The poll also shows that if looking for educational information about
marine mammals, 75 percent of the survey participants would either visit
a marine life park, aquarium or zoo or go to their Web sites.
A 1998 Roper Starch poll also provides clear evidence that programs at Alliance member marine life parks, aquariums, and zoos are educational and provide the public with a heightened appreciation of the importance of conserving marine mammals. Ninety-four percent (94%) of the park visitors interviewed for the poll said, “I learned a great deal about marine mammals today.”
Responses to the poll indicate that seeing living marine mammals enhances the educational experience for the visitors to these zoological parks and aquariums. Almost everyone (97%) interviewed said their experience with living marine mammals had an impact on their appreciation and knowledge of the animals. The impact was greater for those visiting facilities where they actually had an opportunity to interact with marine mammals.
The Roper poll shows that Alliance member marine life parks, aquariums, and zoos successfully teach visitors about marine mammals and, additionally, serve to inform visitors about environmental issues that may have an impact on the animals.
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