What are cetaceans? PDF Print E-mail
Dolphin FAQ
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Friday, 20 March 2009 00:35
Cetaceans is a collective term for whales, dolphins and porpoises. The name is derived from the scientific (Latin) name of these animals: Cetacea.
Last Updated on Friday, 20 March 2009 00:38
 

How do dolphins sleep?

 Dolphins have to be conscious to breath (Williams et al, 1990). This means that they cannot go into a full deep sleep, because then they would suffocate. Dolphins have "solved" that by letting one half of their brain sleep at a time. This has been determined by doing EEG studies on dolphins. Dolphins sleep about 8 hours a day in this fashion. Recent research confirmed that dolphins have only one eye closed when sleeping. The state (open or closed) of one eye remains constant for on average an ...
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How intelligent are dolphins?

 The short answer to this is that we do not know. There is no reliable method to measure intelligence in humans across cultures, so it is not surprising that comparing humans, dolphins, apes, dogs, etc. is impossible. There are some indications of their potential: they are fast learners and can generalize (which is also true of pigs, apes). Also they can learn to understand complicated language-like commands (which is also true of the great apes). Suggested reading: R.P. Balda, I.M. Pepperber...
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How does the dolphin brain compare to the human brain?

 Whales and dolphins have quite large brains. Most authors agree that the size should be viewed in relation to the body size. In some comparisons, brain weight to body weight ratio is used, but it is now more common to use the so-called Encephalization Quotient (EQ), which is calculated as: EQ = brain weight / (0.12 * (body weight ^ (2/3))) (brain weight, divided by 0.12 time the body weight to the power (2/3)). In this formula, brain and body weight should be expressed in grammes. In bottlenos...
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How do dolphins communicate and do they have their own language?

 Dolphins communicate mainly by means of sounds. These sounds include whistles, but also so-called pulsed sounds, which are often described as squawks, barks, rasps, etc. But they also use breaching (jumping and falling back into the water with a loud splash) and pectoral fin (or flipper) and tail (or fluke) slaps (hitting the flipper or fluke on the water surface). Body posturing and jaw popping also have a role in communication. This list is not exhaustive. As for language, we do not know if...
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How does dolphin sonar work?

 Dolphins (and other toothed whales) can produce high pitched clicks. When these clicks hit an object, some of the sound will echo back to the "sender". By listening to the echo and interpreting the time it took before the echo came back, the dolphin estimate the distance of the object. (That's why sonar is also called echolocation: with information from the echoes, a dolphin can locate an object). Depending on the material the object is made of, part of the sound may penetrate into the object ...
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Can dolphins combine information from their sonar with their vision?

 The short answer is: yes, they can. Just like people can visualize an object by just touching it, dolphins can get an idea of what an object looks like by scanning it with their sonar. They can also identify objects with their sonar that they have only been able to see. If they form a visual picture from the sonar information (visualization) or form an acoustical picture from visual information is still unresolved. This capability is called cross-modal transfer and it has been demonstrated in ...
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Can dolphins see colors?

To able to see colors, the retina must have at least 2 different kinds of cones, with different sensitivities. Most mammals have 2 types of cones: L-cones (sensitive to long-wavelength light, red to green) and S-cones (sentitive to short-wavelength light, blue to violet or near UV). Humans and some other primates have 3 types of cones, giving them a better color vision. Only a few landmammals have only one type of cone, which means they are colorblind. All these landmammals are essentially noctu...
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What and how much do dolphins eat?

Bottlenose dolphins eat several kinds of fish (including mullet, mackerel, herring, cod) and squid. The compostion of the diet depends very much on what is available in the area they live in and also on the season. The amount of fish they eat depends on the fish species they are feeding on: mackerel and herring have a very high fat content and consequently have a high caloric value, whereas squid has a very low caloric value, so to get the same energy intake (calories) they will need to eat much...
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How old can they get?

 The maximum age for bottlenose dolphins is between 40 and 50 years. The average age a dolphin can get (the life expectancy) can be calculated from the Annual Survival Rate (the percentage of animals alive at a certain point, that is still alive one year later). For the dolphin population in Sarasota Bay, the ASR has been measured to be about 0.961. This yields a life expectancy of about 25 years. For the population in the Indian/Banana River area, the ASR is between 0.908 and 0.931. This yield...
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Do dolphins live shorter in captivity?

 There is no evidence to support that statement. A recent study, comparing the survival of dolphins in captivity from 1940 through 1992 showed no significant difference in ASR between the "captive population" and the Sarasota Bay population. The ASR for the captive population was 0.944 (life expectancy: 17.4 years). Also in captivity dolphins have reached ages over 40 years. source: R.J.Small & D.P.DeMaster (1995) Survival of five species of captive marine mammals. Marine Mammal Science 11(2)...
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How did dolphins evolve?

 The earliest recognizable cetaceans lived about 50 million years ago. These evolved from the Mesonychids: large land mammals, some of which were carnivorous, some herbivorous. The earliest cetaceans were members of the now extinct family Archaeoceti (the best known of which are Zeuglodon and Basilosaurus). 38-25 million years ago the Archaeoceti disappeared and were replaced by the early Odontocetes (toothed whales) and Mysticetes (baleen whales). The earliest dolphins appeared in the late Mio...
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How can you interact with wild dolphins?

 When swimming, boating or snorkling in certain areas you can encounter wild dolphins. Keep in mind that in the US it is illegal to directly approach dolphins. If dolphins come towards you and choose to interact, that is allowed. Always check the local regulations for interactions with wildlife! In several areas there are boat operators that can take you to areas where there is a good chance to encounter dolphins (Florida, Bahamas, Hawaii, but also Norway and Iceland). A note of warning: there...
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Why do whales and dolphins beach themselves?

If a single whale or dolphin strands, it usually is a very sick (and exhausted) animal. Such an animal often has some infections (pneumonia is almost always one of them) and a lot of parasites (worms in the nasal passages are very common). Sometimes these animals can be rehabilitated, but often they are so sick they won't make it. Some species of whales and dolphins occassionally strand in groups. A stranding of 2 or more animals is usually called a mass stranding. There are a ...
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How deep can dolphins 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 (Globicephal...
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How fast can dolphins swim?

 The dolphin's fast cruising speed (a travelling speed they can maintain for quite a while) is about 3-3.5 m/s (6-7 knots, 11-12.5 km/hr). They can reach speeds of up to 4.6 m/s (9.3 knots, 16.5 km/hr) while travelling in this fashion. When they move faster, they will start jumping clear of the water (porpoising). They are actually saving energy by jumping. When chased by a speedboat, dolphins have been clocked at speeds of 7.3 m/s (14.6 knots, 26.3 km/hr), which they maintained for about 1500 ...
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Where can you find dolphins?

 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 prefered 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. Christoper Helm Publishers, Lond...
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Can dolphins live in fresh water?

 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 f...
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How do dolphins get their 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 they get 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 have live as desert animals, since th...
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Where can you find out more about books, videos etc. about dolphins?

 There is an excellent list of books, videos and CDs on dolphins, which is put together by Trisha Lamb-Feuerstein. This list is updated on a regular basis. You can find that on the Web at the following URL: http://www.physics.helsinki.fi/whale/literature/biblio.html There is a searchable database at the site of the Dolphin Study Group of the National University of Singapore at: http://dsg.sbs.nus.edu.sg/combib.html. They also have a picture database at: http://dsg.sbs.nus.edu.sg/pictures/...
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How many species of dolphins are there?

The taxonomy of whales and dolphins is still subject to change. But in the most common view, the family of dolphins (Delphinidae) consists of 32 different species. Closely related families (the white whales (Monodontidae) and river dolphins (Platanistidae) have 2 resp. 5 species)....
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How can I find dolphin related Web sites?

 Most marine mammal Web sites are listed on the Marine Mammal Links page: http://whale.wheelock.edu/whalenet-stuff/interwhale.html Similar information (grouped by category) can be found at Wesley Elsberry's site: http://www.rtis.com/nat/user/elsberry/marspec.html. Another good starting point is the Aquatic Resources section at the New England Aquarium site at: http://www.neaq.org/....
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Are there dolphin-related mailing lists?

Yes, there are a few e-mail discussion lists, some dealing with marine mammals in general, others with dolphins only. The following are discussion lists. You can participate in the discussions, if you play by the rules set for the group (you will receive instructions once you join). MARMAM - scientific marine mammal discussion list To join send an e-mail     To:     listserv@uvvm.uvic.ca     Subj:     Body:   subscribe marmam Yourfirstname Yourlastnamename You can...
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What is the dolphin species seen in most oceanaria?

The bottlenose dolphin (Tursiops truncatus) ...
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What is the largest dolphin?

The killer whale (Orcinus orca). Male killer whales can grow up to 9.6 m (31.5 ft)....
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What is the smallest dolphin species?

 There is not really one smallest species. The smallest species include: True dolphins (Delphinidae): Tucuxi (Sotalia fluviatilis) - 1.3 to 1.8 m Hector's dolphin (Cephalorhynchus hectori) - 1.2 to 1.5 m Black dolphin (Cephalorhynchus eutropia) - 1.2 to 1.7 m Commerson's dolphin (Cephalorhynchus commersonii) - 1.3 to 1.7 m River dolphins (Platanistidae): Franciscana (Pontoporia blainvillei) - 1.3 to 1.7 m Porpoises (Phocoenidae): Vaquita (Phocoena sinus) - 1.2 to 1.5 m Finless porpois...
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What is the difference between dolphins and porpoises?

 Dolphins and porpoises belong to different whale families. The most obvious differences are: - dolphins have a falcate (hook-shaped) dorsal fin, whereas porpoises have a triangular dorsal fin. - dolphins have conical teeth; the teeth of of porpoises are spatula shaped. - most dolphin species have a distinct beak. Porpoises don't, giving their head a more rounded, blunt shape. ...
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What is a dolphin fish?

 Dolphins are marine mammals, but there is also a fish species that's often called "dolphin" or "dolphin fish". Its scientific name is Coryphaena hippurus. To avoid confusion with the mammal species its Spanish name "dorado" or its Hawaiian name "mahi mahi" is often used. Because of the confusion between the mammal and the fish species dolphins have in the past erroneously been called porpoises, especially in some US regions, where the fish species is common. In older books you can encounter t...
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What are cetaceans?

Cetaceans is a collective term for whales, dolphins and porpoises. The name is derived from the scientific (Latin) name of these animals: Cetacea....
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Are whales and dolphins endangered?

 For most species, the answer is probably "No", although it is very difficult to get a good estimate of the size of populations on these water living creatures. A number of species are endangered: the Indus river dolphin, the baiji (there are only about 100 left), the vaquita, the northern right whale and the blue whale. Another group of species is listed as "vulnerable" (which means that they are not in immediate danger of extinction, but also far from safe). These are: the Ganges river dolphi...
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An overview of the species of whales and dolphins (the order Cetacea)

order CETACEA (WHALES AND DOLPHINS) suborder MYSTICETI (BALEEN WHALES) family BALAENIDAE (RIGHT WHALES) Eubalaena glacialis northern right whale Eubalaena australis southern right whale Balaena mysticetus bowhead whale Caperea marginata pygmy right whale family BALAENOPTERIDAE (FIN WHALES or RORQUAL WHALES) Balaenoptera musculus blue whale Balaenoptera physalus fin whale Bal...
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Where can you see whales and dolphins in the wild?

There are quite a number of whale watching tour operators in many parts of the world. A comprehensive list is available on the Helsinki Whale Watching Web site at: http://www.physics.helsinki.fi/whale/...
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