Questions and Answers About Dolphins

Why do dolphins visit the Interaction Zone?
We are not sure why. Dolphins are very intelligent, social animals. They are also very curious and will stay in the Zone on average for 30 minutes however they may stay up to 1-2 hours. We don't encourage them to stay longer, as this may impact on their normal behavior. They seem to stay until they are no longer interested.
We follow strict government guidelines to operate the Interaction Zone and the boat tours in Koombana Bay to ensure we have a low impact on the dolphins' lives.

What time do dolphins visit?
They are wild dolphins and their presence cannot be predicted. They come and go whenever they want to. However, most visits occur between 8.00 am and 12.00 noon. They rarely visit after these times and if they do, it’s only for a very short time.

Do dolphins visit more in summer than winter?
Yes. The numbers and frequency of visits increase during the summer months. The exact reason is not yet known but may be due to several conditions – eg. less visibility during winter, fish migration out of the Bay, fewer dolphins in the bay due to dolphin migration (particularly males).

Do we feed the dolphins?
We have a government licence to feed only the regular dolphins who come into the Interaction Zone. These dolphins (approximately 7) may receive a total of 350 grams. They may receive up to 250 grams on their 1st visit and if they come back later, they receive 100 grams on the 2nd visit. Dolphins can eat between 8-15 kilos per day. We see this as a treat and the dolphins quite often do not receive the full 350gms and sometimes they refuse our fish. They are fed within the first 30 minutes of their visit to ensure they don’t stay longer waiting for food.

Is this like Monkey Mia?
We have a separate licence to Monkey Mia and different conditions. Monkey Mia dolphins are fed a total of 2kg per dolphin. The feeding procedure is very structured and the dolphins will leave the feeding area as soon as they realise they will not receive any more fish for that visit.

Are the dolphins in Bunbury the same as at Monkey Mia?
A. No. Both are Bottlenose dolphins, however the Bunbury dolphins are Common Bottlenose dolphins (Tursiops truncatus) whilst the Monkey Mia species are Indo Pacific Bottlenose dolphins (Tursiops aduncas). Some features of T. aduncus are actually closer to features of another genus, Stenella (spotted and spinner dolphins). Sophisticated genetic methods are being used to revise the taxonomic status of several Cetacean species.
Both species live in shallow waters and are smaller than the offshore type, which live in the deeper parts of the ocean.
B. The dolphins of Koombana Bay are larger and heavier than those at Monkey Mia.

What research is being done here at the DDC?
For a clear understanding of the research conducted here at the DDC please refer to the research pages on our website.

Dolphin Biology

Is a dolphin a fish?
No. Dolphins are mammals. They are warm blooded and have lungs and breathe air. They give birth to their young alive and nurse them on mother's milk.

What is the difference between a Dolphin and Porpoise?
A. Dolphins have a long beak (rostrum), curved dorsal fin, sharp pointed teeth, larger brain in relation to its body size.
B. Porpoises have a snub rostrum, triangular fin (except for the finless porpoise), square shaped teeth, generally smaller than the dolphin. There are no porpoises in Australian waters.

What is the difference between Dolphins and Whales?
Dolphins and whales are both members of the order Cetacea. Dolphins belong to the sub-order Odontoceti and differ greatly from the baleen whales who are in the sub-order Mysticeti. They have teeth; use echolocation to navigate, communicate and find food; and are smaller. They are in the same family Delphidinae as killer whales (Orca), pilot whales, melon headed whales along with another approx. 25 species.

How long are dolphins?
Koombana Bay dolphins may be within 2–3 metres in length. Bottlenose dolphins can grow up to 4 metres long in cold water regions.

What do dolphins weigh?
Roughly 1cm = 1kg. Koombana Bay dolphins average weight is 150–200kg. In general and depending on where they reside, dolphin weight can vary from between 100 and 400kg.

Are males bigger than females?
Male dolphins are slightly bigger than females, however the variation is minimal.

What is the difference between males and females?
It is almost impossible to determine the sex of a dolphin without looking closely at the underside of their bodies. All dolphins have genital slits and a separate anal slit. Females have small mammary slits on either side of the genital slit.

Which are the biggest dolphins?
Orcas (killer whales), which can grow up to 9.5m long and weigh 7200kg.

How long do dolphins live?
A wild dolphin can live into its 40's. It is estimated that dolphins will live 35–45 years. The average life of a dolphin may be lower because of injury, sickness or shark attack. It is hard to measure in a healthy, normal free ranging animal which spends so much of its life out of human view.

Do dolphins get sick?
Yes. They can become sick or get injured. Dolphins can have dental disease. They can catch bacterial, fungal or viral diseases. They can have parasites and may become sick due to man-made pesticides. They can also be subject to shark attack, especially if they are sick or young.

Do dolphins have natural enemies?
Yes. Other Bottlenose Dolphins, Orcas (killer whales), sharks and humans.

Are dolphins affected by the fishing industry?
Yes, these are mostly the spotted and spinner dolphins. Yellow fin tuna associate with these species of dolphin. Fishermen encircle the dolphins with purse-seine nets in order to capture the tuna below them. Dolphins can become entangled in the nets and drown. Around the Bunbury region, there is minimal commercial fishing. The fishermen are now being made to use techniques which do not place the dolphins in direct danger.

Are dolphins intelligent?
Bottlenose dolphins have larger brains than humans and show a degree of intelligence unmatched within the order Cetacea.

How do dolphins breathe?
A. Dolphins have lungs. They breathe through a single blowhole on the dorsal surface of the head. Dolphins hold their breath when they swim or dive under water. As they go underwater, strong muscles shut the blowhole tight. Dolphins open their blowhole and begin to exhale just before they surface. As a dolphin exhales, the seawater that has collected around the blowhole is carried up with the exhaled gases and forms a visible mist. Once on the surface, they quickly inhale and relax the muscular flap to close the blowhole.
B. Dolphins are voluntary or conscious breathers. This means they have to remember when to breathe (humans breathe automatically). It also means that dolphins cannot receive anaesthetics to be treated for illness because they will stop breathing and die.

How long can a dolphin stay under water?
Average time is 2–3 minutes. However, they can stay under water for up to 8–15 minutes.

How can a dolphin hold its breath for so long?
Dolphins have 3 adaptations they use to conserve oxygen while underwater.
They slow their heart rate so they can use their oxygen supply more slowly;
When they dive, the blood is shunted away from tissues which can survive with low oxygen, to the heart, lungs and brain where it is needed;
Muscles have an oxygen-binding protein called myoglobin (similar to haemoglobin). This protein stores oxygen and helps prevent a deficiency of oxygen in the muscles.

How deep do Bottlenose dolphins dive?
Most Bottlenose dolphins dive to depths between 3-45 metres. They may dive to depths of 300 metres. This is quite shallow compared to the larger toothed whales. For example the sperm whale can dive up to 3,000 metres.

Do dolphins have bones?
Yes – however their bones are lighter and spongier than those of land mammals.

How do dolphins sleep?
Researchers have found that dolphins spend about 33% of each day sleeping by having short 'cat naps'. When sleeping, they lie with their blowhole exposed above the water surface. They rest one side of their brain, while the other side is active. They regularly alternate the side on which they choose to lie.

Can dolphins smell?
Studies have shown that dolphins can in fact detect the four primary taste qualities of salt, bitter, sweet and sour, although sensitivity to these qualities seems to be about an order of magnitude less than human sensitivity.

Do dolphins have ears?
A. Yes, they can hear very well. They have tiny holes either side of the head. The specialised anatomy of a dolphin ear helps it to localise sound underwater, so that they can work out exactly where the sound is coming from. Humans can't do this underwater.
B. Most sound reception probably occurs however, through the fatty tissue in the lower jaw.

How good is a dolphin's eyesight?
Dolphins are able to see clearly in water and in air. They have a strong lens which changes shape to focus light whether they are in water or in the air. Their eyes are able to adjust to dim or bright light. They have mucus which covers their eyes to keep them hydrated. Dolphins can distinguish between colours (although it is not known how many colours can be seen).

Do dolphins close their eyes?
Yes. Dolphins have upper and lower eyelids and close their eyes when asleep. They also close their eyes to protect them from objects in the water.

What is echolocation?
Dolphins use echolocation to ‘see with their ears’ by listening for echoes. Echolocation is a biological sonar which dolphins use to find food. They are able to effectively determine size, shape, speed and other characteristics of their targets (e.g. swimming direction) across a distance of 5–20 metres.

What is the body temperature of a dolphin?
The core body temperature is normally between 35°C and 36.9°C - human body temperature is 37.3°C. Its outer body temperature is usually cooler than this.

How do dolphins keep warm?
A. Heat is lost in water 25 times faster than in air. To keep heat from escaping, dolphins have a thick layer of fat known as blubber, just beneath the skin. This blubber acts as an insulator.
B. Special blood vessels absorb heat and carry it back to the core regions of the body. The arteries in the flippers, flukes and dorsal fin (extremities of the dolphin where the greatest amount of heat is lost) are surrounded by veins which bring the warmed blood back to the heart, rather than losing heat to the environment. This is known as counter current heat exchange. When a dolphin dives, the blood is shunted away from the surface of its body, thus conserving body heat. Dolphins also have a high metabolic rate.

Do dolphins swim like fish?
No. Fish move through the water by moving their tail from side to side. Dolphins move their flukes up and down.

How fast can a Bottlenose dolphin swim?
They can reach up to 40km per hour for short distances. Normally dolphins swim at around 8-16 km/hr. Unlike fish which have a vertical tail that moves from side to side, dolphins have a horizontal tail (or fluke) which it moves up and down to swim. Unlike a lot of mammals, dolphins do not have fur although some have whiskers around their mouths when first born. Instead dolphins have evolved with smooth, soft skin which makes swimming easier. Their bodies are streamlined to offer the least resistance in the water and the skin continually sheds dead skin cells to keep their body smooth. This is called ‘sloughing’.

How many teeth do Bottlenose dolphins have?
A. Usually 76-98. The number can vary between 18-26 relatively large teeth on each side of the jaw. The teeth are sharp, conical shaped and designed for grabbing, rather than chewing.
B. Dolphins only have one set of teeth. Calves get teeth at approx. 5 weeks old.
C. You can count the age of a dolphin by its teeth. When a longitudinal section of the tooth is made, the rings can be counted

Can dolphins taste their food?
Bottlenose dolphins do have taste buds, but they have not been extensively studied. However, it has been noted that dolphins do have strong preferences for certain species of fish for food and can distinguish between tastes.

Do dolphins drink water?
No, dolphins do not drink water. They get what they need from the fish they eat.

How much does a dolphin eat per day?
They can eat between 8–15 kilograms (4 to 15% of their body weight) per day. The amount a dolphin will eat varies upon the temperatures of the water they inhabit. A dolphin will eat more fish per day during the colder months of the year.
The dolphins of Koombana Bay eat most kinds of fish, but the species is determined by the season. The fish are generally mullet, herring, whiting, tuna, salmon, tailor, squid, octopus, crabs and occasionally stingrays.

How do dolphins catch fish?
A. In open waters, a group of dolphins will often co-operatively hunt by encircling a large school of fish and herding them into a small dense mass. They stun the fish by their echolocation clicking sound, and sometimes by the tail flukes.
B. A group of dolphins may also herd schools of fish against a sandbar or shoreline where the fish become trapped in shallow water. Dolphins will swoop in to catch the fish. This occurs in the Interaction Zone and along the shores of Koombana Bay.

How do dolphins eat their food?
Dolphins swallow fish head-first and whole. They use their teeth to grasp the prey, the tongue turns the fish around so that it’s able to be swallowed head first. This stops the fish’s spines and scales from cutting the throat of the dolphin. If they catch large prey, they use their rostrum to break up the fish.

Do dolphins court each other?
Yes. Bottlenose dolphins touch each other often with their flippers, flukes and rostrum. They nuzzle against each other and swim close together. This can last for an hour or even longer. Dolphins are sexually active all year but courting behaviour or touching does not always lead to mating.

How do dolphins mate?
Male and female dolphins swim belly to belly. The female is below the male when the erect penis emerges from the male’s genital slit. Mating usually does not take a long time, only about 30 seconds. It may be repeated many times to ensure success.

Do dolphins mate together for life?
No. They have many partners in their lifetime. A female will mate with several males when she is receptive. Males are known to compete aggressively for the females. The males have large testes, which is a known characteristic of animals who mate with several partners.

When do dolphins reach sexual maturity?
A. Females – approximately 9 to 10 years.
B. Males – approximately 10 to 13 years.

How often to dolphins breed?
Dolphins give birth approximately every 4-8 years. They only give birth to one calf at a time and may have up to 8 calves in a lifetime. Twins are virtually unknown.

How long is the mother pregnant?
Gestation period is usually 12 months but can vary between individuals.

When do mothers give birth?
Calves are born during spring and summer months. In Koombana Bay, this can be between November and April.

How is a calf born?
Tail first. This avoids the calf drowning if complications arise during the birth. Births have been known to take 2 hours but have been witnessed in minutes. The mother does not seem to be interested in the placenta.

What do calves look like when they are born?
Calves look much like adults except they weigh about 30kg at birth and may be up to 1.2 metres. Newborns have folds or creases in their skin (fetal folds). There are also large creases in their skin and dorsal fin. Their flippers may be curled or floppy. The dorsal fin takes about 1 week to harden.

Do calves talk to their mothers?
A mother dolphin may whistle (known as a signature whistle) to her calf continuously for several days after giving birth. It is thought that this form of imprinting helps the calf learn to identify its mother. The whistling seems to be a form of communication, whereas the clicking sound heard is for echolocation.

Are calves good swimmers?
Yes. It takes about 1 week for the calf's fins to harden, however. The newborn may need help from the mother who has been known to push the calf to the surface. After about 2 weeks a calf is much more co-ordinated and can begin to take deeper dives. Dolphin mothers have been known to synchronise their breathing with the calf.

How do calves suckle?
A. They suckle from mammary slits on either side of the mother's genital slit. Beneath the genital slits are teats. The calf places its tongue into the slit and forms a cone shape with it in order to latch onto the teat. The milk is actually more of a paste and it is controlled by the mother, not the calf.
B. The milk is very rich in fat compared to human or cow’s milk. It is estimated that mothers nurse their calves 4 times every hour in the first week of life.
C. The calf can grow 7 times its weight in the first year.

How long do calves suckle?
In the wild, dolphin mothers can nurse a calf for 18 months or more, even 3 years. The mother starts weaning the calf onto fish at approximately 5-6 months. Dolphins will wean their calves before giving birth to another.

Do dolphins make good parents?
The role of the male usually ends with mating, however there is some evidence that the males visit females with calves during the summer period. Female calves tend to stay with their mothers longer than male calves. It is suggested that female calves will learn to raise young by staying with their mother.
Questions and Answers About Dolphins

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