Dolphin Frequently Asked Questions
1) Why is a dolphin a mammal and not a fish?
A. They breathe air. Dolphins breathe air from their blowhole, which is the hole on top of their head. All of the sounds that they make come from the blowhole as well.
B. They are warm blooded.
C. They have hair. Dolphins have whiskers when they are first born. They are found on their rostrum (the top part of the jaw bone) and fall out a few days after they're born. If you look closely at a dolphin's rostrum you will see tiny black spots, this is where their whiskers once were.
D. They give live birth. Baby dolphins (called calves) are born live like human babies and most other mammals. Dolphins do not hatch from eggs like fish do.
E. They nurse their young. They have fringes on their tongues that help them make an airtight "straw." The dolphin calf would then swim underneath its mother and put the "straw" in one of its mother's mammary slits, then drink milk without ocean water entering the calf's mouth.
2) What are cetaceans?
Whales, dolphins, and porpoises all belong to the same scientific, taxonomic order called cetaceans.
3) What does each fin on a dolphin's body do?
The fin in the center of the back is called the dorsal fin. It is used as a stabilizer; it keeps the dolphin upright, straight and balanced when it swims through the water. The dorsal fin is also the dolphins fingerprint. There are no two dorsal fins that are identical. Each has its own unique shape, height, thickness, and notches. Scientists utilize the appearance of dorsal fins to identify individuals in the wild.
The fins on each side of its body are called the pectoral fins. They are used to stop and steer the dolphin. If you took an x ray of the pectoral fins they would look like our own human hand, with five digits inside.
The tail fin is also called its flukes. They are called flukes because there is a notch in the center that separates the right from the left side. A dolphin can lift 80% of its body out of the water by using its tail flukes; however the tail itself has no muscles in it. All of the muscles form at the base of the tail, called their peduncle. The tail is composed of cartilage.
4) How many teeth does a dolphin have?
Bottlenose dolphins have 80-100 very sharp conical-shaped teeth in their mouth. Unlike us, dolphins only have one set of teeth their entire lives. If they lose or break a tooth, they will just have an opening where the tooth was located, whereas we lose our “baby” teeth as young children and grow another set in their place.
5) Do dolphins have ears?
The ears of a dolphin are small pinholes on each side of its head.
6) How long can a dolphin hold its breath?
Dolphins can hold their breath for about 10 minutes on average. Typically, though, they breathe about 4-5 times each minute
7) Do dolphins sleep?
We, as humans, are involuntary breathers. This means that we do not have to think about every breath that we take. Dolphins on the other hand are voluntary breathers, and they do have to think about every breath that they take. Dolphins do not sleep like we do since they have to think about each breath and they live in the water. They could drown if they fall asleep. Basically, they shut down half of their brain at a time for rest, while the other half stays awake to breathe. They take “naps” throughout the day.
8) How deep can dolphins dive?
The deepest dive ever recorded for a bottlenose dolphin was 300 meters (990 feet) by Tuffy, a bottlenose dolphin trained by the US Navy. The average depth that dolphins dive during their natural behavior, without specific training depends on the species of the animal (and therefore the habitat in which they live, such as offshore, deeper waters versus inshore or coastal more shallow waters).
There is fairly limited data on this topic for toothed whales, also known as odontocetes (the taxonomic suborder to which dolphins and porpoises belong). Some research studies thus far have indicated that short-beaked common dolphins (Delphinus delphis) may forage at depths of "up to" 260 m for eight minutes or more, although most dives are around 90 m deep, last about three minutes and are mostly at night. Pantropical spotted dolphins (Stenella attenuata) dive to at least 170 m; most of their dives are to 50 – 100 m for two to four minutes and most feeding appears to occur at night. Atlantic bottlenose dolphins (Tursiops truncatus) near Grand Bahama Island off southeastern Florida often dive to the ocean bottom (seven – 13 m depth) and burrow into the sediment (“crater-feeding”) to catch fish dwelling or hiding there. Sperm whales (Physeter macrocephalus) dive to depths of up to 2000 m for 60 minutes or more. (Perrin, W. F., Würsig, B., Thewissen, J. G. M. (2002). “Encyclopedia of Marine Mammals.” Academic Press, CA.)
9) How fast can dolphins swim?
10) Do dolphins live shorter in captivity?
No. This is likely due in large part to the medical attention and the consistent, high quality supply of food they receive. A study comparing the survival of dolphins in captivity from 1940 through 1992 showed no significant difference in annual survival rates (ASR) between the "captive population" and the Sarasota Bay wild population. The ASR for the captive population was 0.944 (life expectancy: 17.4 years). In captivity dolphins have also reached ages over 40 years and one is even over 50 years old.
11) What is the difference between dolphins and porpoises?
Although dolphins and porpoises belong to the same whale family, there are differences between them. The most obvious differences are:
- Porpoises have spade-shaped teeth, whereas dolphins have conical teeth.
- Porpoises have a rounded, blunt-shaped head, whereas most dolphin species have a distinct beak or rostrum.
- Porpoises though generally smaller in size, tend to have a robust, broader and fuller body, whereas dolphins tend to have a longer, streamlined shape.
- Porpoises have a triangular dorsal fin, whereas dolphins have a falcate (hook-shaped) dorsal fin.
12) How many different species of dolphins are there?
13) What and how much do dolphins eat?
Bottlenose dolphins eat several kinds of fish including mullet, mackerel, herring, cod, capelin and squid. 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 therefore a high caloric value, whereas squid has a very low caloric value. On average an adult dolphin will eat four to nine percent of its body weight in fish daily, so a 550 lb dolphin will eat 22-50 lb of fish per day.
14) How do dolphins get their water?
Dolphins cannot drink the salt water in which they live. They get most of their water from the food they eat. Also when they metabolize (burn) their fat, water is released in the process. Their kidneys are also adapted to retaining (conserving) as much water as possible.
15) How long can they live?
Life expectancy for dolphins differs per geographic region and species. Bottlenose dolphins can live into their 40’s. However, this appears to be a maximum age comparable to a human living to be about 100 years old. Dr. Randy Wells’ studies of the Sarasota Bay, Florida dolphins, have found that only one to two percent will reach that age at sea. The average age that these animals live until is between 15-16 years old. The oldest, scientifically aged dolphin in the wild was 48 years old. The oldest in an aquarium is over 50, and that dolphin is captive-born.
16) Why is their body a lighter color on the underside?
The color of a dolphin actually protects it in its environment. This phenomenon is called counter-shading. If a predator such as a shark was swimming above a dolphin and looked down at it, the grey color that the shark would see would help it to blend in with the bottom of the ocean floor. If that same predator was underneath the dolphin looking up at it, its pinkish-white belly would blend in with the sky; therefore this counter-shading camouflages them.
17) Can dolphins beat up sharks?
If there was a fight between a healthy shark and a healthy dolphin both have a 50/ 50 chance at winning. For the most part sharks and dolphins avoid each other, though sharks may prey on ill or very young dolphins.
18) Where do bottlenose dolphins live?
Bottlenose dolphins are distributed all over the world in both temperate and tropical waters. They occupy a variety of habitats, ranging from near shore, coastal areas to deep offshore waters. There are also five species of fresh water dolphins.
19) Can dolphins live in fresh water?
River dolphins such as the Platanistidae (Ganges and Indus river dolphins), the Iniidae (the Boto or Amazon River dolphin) and the Pontoporiidae (the Baiji and the Franciscana) all live in fresh water. One species that can be found both in fresh water (the Amazon River) and in coastal sea waters is the Tucuxi (Sotalia fluviatilis
Salt water species don't do well in fresh water. Although they can survive for some time, they will be exhausted by the lack of buoyancy in fresh water. Also, after a while their skin will start to slough as the fresh water does not support their skin or eyes and they can develop serious infections.
20) How can you observe or interact with wild dolphins?
Anytime you are in ocean water, there is a small chance that you will have an encounter with a curious wild dolphin. Understand however that it is illegal in the U.S. to approach a wild dolphin. NOAA Fisheries, the US federal government agency that oversees and manages marine mammals, recommends that they be observed from a distance of at least 50 yards. In order for you to interact in any way with the animal legally, the dolphin must approach you. Be aware however, that it is not a wise idea to allow any wild animal to get close to you as it could present a real danger to the people and animals involved.
A boat captain in your local marina may offer to take you to an area where you have a good chance of seeing dolphins. Be aware that if the boat operator tries to lure the dolphins with food, he is committing a crime. This behavior is illegal and has a very negative effect on wild dolphins for the following reasons:
***Remember, it is illegal to feed or harass wild dolphins and all other marine mammals***
- It can decrease the dolphins’ instinct to hunt for food
- It can decrease the dolphins’ instinct to stay away from boat traffic and humans
- It can make them dependent on humans.
21) Where can you work with dolphins or other marine mammals?
Jobs working directly with marine mammals are usually found at oceanariums, aquariums and marine parks in the US and many other countries. Government agencies also offer jobs for biologists to work with marine mammals in the fields of research and conservation.
22) How intelligent are dolphins?
Intelligence is defined as 1 a) the capacity to acquire and apply knowledge, b) the faculty of thought and reason.
More simply put, it is the ability to learn, understand, or deal with new or trying situations; and the ability to apply knowledge to manipulate one’s environment. It is also defined as the ability to think abstractly. Quantification of intelligence is difficult to do, and it is especially difficult to compare across species.
We can say from experience that dolphins are fast learners and seem to be able to generalize some of the information they learn. However, to date there is no evidence to suggest that dolphins or any other living species is as intelligent as humans. Contrary to popular belief, brain size is not an indicator of intelligence. Complex brain structure is more closely related to level of intelligence in a particular species
23) How do dolphins communicate and do they have their own language?
Language is defined as a systematic means of communicating by the use of sounds or conventional symbols, including the rules for combining the components of such sounds and/or symbols. There is a difference between communication and language. All animals can communicate in some form or manner, but only humans are known to have a language which has the following characteristics: communication of thoughts and feelings through a system of arbitrary signals, such as voice sounds, gestures, or written symbols.
Dolphins communicate mainly by means of sounds. These sounds include whistles, and also so-called pulsed sounds, which are often described as squawks, barks, rasps, etc. But dolphins 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), as well as body posturing, jaw popping and touch as other means of communication.
In regards to language, several studies have demonstrated that dolphins can understand a structured language like ours. Some studies also indicate that dolphin vocalizations are complex enough to support some form of language. However, to date it has not been demonstrated yet that they indeed use a language for communication among themselves, nor has it been demonstrated that they can understand our form of verbal language.
24) How does dolphin echolocation work?
Dolphins (and other toothed whales) can produce a series of high-pitched clicks which are projected from their melon (the part of their head that resembles a “forehead”) as sound waves. When the clicks hit an object, some of the sound will bounce (or echo) back to the "sender.” The dolphin then receives this information back through its lower jaw, which has an oil-filled cavity that conducts the sound waves back to the nerves that will then relay the information to the brain. With its echolocation, the dolphin is able to obtain information about the structure, size, and density of an object (even the speed and direction it is traveling if the object is moving).
25) Why are dolphins important to the ecosystem?
Dolphins are very important because they give us a view into what may be negatively impacting their ecosystem. Because dolphins are at the top of the food chain in the ocean, we can use them as a "bio-indicator" to show the status of their environment. Monitoring and protecting dolphins actually protects all marine animals in the dolphins’ ecosystem, as well as the ecosystem and environment itself. Monitoring dolphins that live in coastal areas protects not only marine animals, but also humans because we share many of the same sea foods and consequences of pollution.
26) What causes dolphin strandings? Why do dolphins beach themselves?
Single animal strandings usually take place when an animal is sick or injured. Often the animal will suffer from parasites, i.e. worms in the nasal passage, an infection such as pneumonia, or another type of illness. More often than not, these animals have a very small chance of surviving.
There are several theories as to what causes group strandings or mass strandings of marine mammals:
- Deep water animals cannot "see" a sloping sandy beach properly with their sonar. They detect the beach only when they are too close to land already and they will panic and run aground (Source: W.H. Dudok van Heel (1962): Sound and Cetacean. Neth. J. Sea Res. 1: 407-507).
- Whales and dolphins may be navigating by the earth's magnetic field. When the magnetic field is disturbed (this occurs at certain locations) the animals get lost and may run into a beach (Source: M. Klinowska (1985): Cetacean live stranding sites relate to geomagnetic topography. Aquatic Mammals 11(1): 27-32).
- In some highly social species, the group leader may be sick and wash ashore. The other members try to stay close and may strand with the group leader (Source: F.D. Robson (?) The way of the whale: why they strand - unpublished manuscript).
- When under severe stress or in panic, the animals may fall back to the behavior of their early ancestors and run to shore to find safety (Source: F.G. Wood (1979) The cetacean stranding phenomena: a hypothesis. In: J.B. Geraci and D.J. St. Aubin: Biology of marine mammals: Insights through strandings. Marine Mammal Commission Report no: MMC-77/13: pp. 129-188).
27) What dolphins and whales are at highest risk for stranding?
Most mass strandings occur in toothed whale species such as sperm whales, pilot whales and pygmy sperm whales. According to Rogan et al. (1997) pilot whales, white-sided dolphins and false killer whales are the species that mass strand the most. Single strandings are often bottlenose dolphins.
28) What should be done for stranded dolphins?
29) What is the current "success rate" of rescuing and rehabilitating dolphins?
This is a difficult number to quantify and measure in a standard and systematic way. As mentioned above, though most dolphins and whales that strand have a very small chance of survival, the individual animal’s chance of survival depends largely on several factors. The most significant of these factors include what condition the animal is in when it is discovered, the species of the animal and the expertise of the staff and facility that respond and care for it.
30) Who should be contacted if a stranded dolphin is found?
Your local marine mammal stranding network should be called immediately. Call local police immediately if you do not know the number of the nearest marine mammal stranding network. If you live in the Mississippi Gulf Coast area, you can call IMMS at (888)SOS-DOLPHIN (888-767-3657).