Dolphin & Whale Fun Facts

Are dolphins & whales mammals?

Yes, dolphins and whales are mammals. Like all mammals, they breath air, are warm blooded, give birth to live young, lactate and have hair. The ancestors of whales and dolphins lived on land millions of years ago and it is thought they were small dog-like mammals.  Around 60 million years ago, these ancestors began evolving and adapting to live in the ocean. As they adapted to living in the ocean, their front legs turned into paddle-shaped flippers, they lost their back legs, their tails grew larger and widened horizontally to form flukes, and they developed a thick layer of fat, called blubber, to keep them warm in the ocean. Their skulls elongated and the nostrils shifted to the top of their heads (blowholes) to aid in breathing at the ocean’s surface. Cetaceans also developed a series of adaptations related to diving, which include the ability to store more oxygen in their blood and muscles and having more blood volume relative to their body size than land mammals.

What does cetacean mean?

The word cetacean comes from the Latin word cetus, used to describe any large sea creature, and the Greek word ketos, which was a sea monster or whale. Cetacean is the name for the group of completely aquatic marine mammals commonly known as whales, dolphins and porpoises.  All species are characterised with two front flippers, and their tails, called flukes, are flattened horizontally, which provide tremendous swimming power. There are around 90 living species of cetaceans, which are divided into two groups.  The first is the Odontoceti, the toothed whales, which consist of around 70 species, including the dolphin (which includes killer whales), porpoise, beluga whale, narwhal, sperm whale, and beaked whales. The second is the Mysticeti, the baleen whales, which are filter-feeders, and include the blue whale and humpback whale.

What is the difference between a dolphin and a porpoise?

Dolphins and porpoises are types of toothed whales belonging to the scientific suborder Odontoceti. For many years, people believed there were no differences between dolphins and porpoises. However, a number of distinct differences exist. Porpoises belong to the scientific family Phocoenidae and dolphins to the family Delphinidae.

This means dolphins and porpoise differ from each other on a physical level. Most dolphins have a pronounced rostrum or beak, a slender body and can grow much larger than porpoises (biggest dolphin is the Orca reaching up to 9m in length and the smallest dolphin is the Hector’s dolphin growing to 1.5m in length). The family of porpoise contains some of the smallest cetaceans that exist. The smallest porpoise is the Vaquita with a maximum length of 1.5m and the largest porpoise is the Dall’s porpoise reaching 2.4m in length. Porpoises have a more robust body than dolphins, and lack a rostrum or beak. Porpoise are also a lot shyer than dolphins and do not often come up to boats or people.  One of the biggest differences is the shape of their teeth. Dolphins have cone-shaped teeth and porpoises have spade-shaped teeth.

Dolphins are more prevalent than porpoises, with 37 species of dolphins belonging to the family Delphinidae (oceanic and marine dolphins) and only 7 species of porpoises in the Phocoenidae family.

Where did the sperm whale get its name from?

The name sperm whale comes from the waxy substance called spermaceti that is found in the head of this species. Early on people believed that this waxy substance was the semen or sperm of the whale. This was later disproven. The function of spermaceti is not well understood, but it is thought that its primary function is to amplify the sonar clicks and secondly to aid in maintaining the whales buoyancy.

How long do dolphins live?

The life span for most species of dolphins is not known. However, it appears that the life span of can be different between species of dolphins. Bottlenose dolphins can live to between 50-60 years of age in the wild. Orcas or killer whales may live to over 120 years of age.

How long can dolphins hold their breath?

Normally dolphins come up to breathe every few minutes but are able to hold their breath for much longer. Bottlenose dolphins can hold their breath for over 15 minutes. Orcas can also hold their breath for about 15 to 20 minutes.

How deep do dolphins dive?

Bottlenose dolphins can dive to depths of less than 50 meters. However, bottlenose dolphins are capable of diving to depths of 300 meters. This record was set by Tilly, a dolphin that was trained by the US navy. Other species of toothed whales can dive even deeper. A recent study into belugas revealed that this species can dive to depths up to 1250 meters. The deepest diver of all the toothed whales is the sperm whale. This species can dive up to 3000 meters and can hold its breath for 2 hours!

What do killer whales eat?

Killer whales, also known as orcas, are carnivorous and eat a wide variety of marine animals including fish, squid, octopuses, seals and sea lions, dolphins and porpoises, sharks and rays, large whales, seabirds and more. Orcas live in groups, or pods, with up to 40 individuals, and hunt co-operatively in packs.  Their diet depends not only on where they live, but also on how the pod members in past generations have learnt to hunt their prey, with these techniques being taught to their young, and they are unlikely to switch diets.  For example, the southern resident Orcas living along the North American Pacific coastline diet is primarily chinook salmon, while orcas in Argentina and the Crozet Islands eat marine mammals such as seals, sea lions and whales.

How big is a blue whale?

Blue whales are the largest animal ever known to have lived on earth, even larger than any dinosaur. Blue whales grow up to 33m in length (3 school buses, and twice as along as a T-Rex dinosaur) and can weigh up to 190,000kg. Their heart alone is the size of a small car, and their calves are a whopping 7 meters in length, weighing in the same as an adult African elephant.  Females are larger than males.  Even though blue whales are the largest animal on the planet, one of their main types of prey are krill, small shrimp-like creatures the size of your little finger. During feeding season they eat up to 40 million krill a day!

Is a whale shark a marine mammal or fish?

A whale shark is a fish, not a marine mammal. The name is deceiving, as it is not a whale but its size is similar to many of the bigger whales and it filter feeds like baleen whales as well. It is a shark, and the largest fish in the ocean, reaching as long as a school bus and between 12-18 metres in length and is not dangerous to humans, but in fact very docile.

­What is a dolphin fish?

A dolphin fish, also called Mahi Mahi, is a fish that lives in schools in the tropics. It is a misleading name, as it is not related to dolphins at all. It has a narrow body, a high profile head and a high dorsal fin that runs almost the full length of the fish. It is colour is varied and can be silver/white to yellow/green with iridescent blue spots. It can grow to a maximum size of 2 metres, and lives in temperate, tropical and sub-tropical seas worldwide.  It is not known why the term “dolphin” became attached to the mahi mahi fish. One theory is that underwater, the dolphin and dolphin fish make similar high-pitched noises to communicate. Therefore, the dolphin fish may get its name because of this dolphin-like trait.

Do dolphins grieve?

Dolphins display a range of care giving behaviours that include showing support to stressed, injured and dying members in their pod. Their behaviour around a dying member can be associated with the feelings of grief and loss. It is thought that all dolphin species display this behaviour, which is also common in other mammals and birds. Bottlenose dolphin and orca mothers have been observed continuously pushing their deceased calf with the rostrum or melon (head?) towards the surface. They also displayed erratic behaviours such as repeatedly surfacing sideways. Sometimes this behaviour is prolonged for a few days. In 2018 an orca named J35, a member of the J Pod in the Northwest Pacific Coast off Canada, lost her calf. Scientists observed J35 morning her calf for 17 days, after which she dropped her dead calf.

Do dolphins interact with humans?

Even though human interactions with dolphins is highly discouraged for the safety and wellbeing of dolphins and humans, special human-dolphin interactions date back thousands of years. One type of interaction is cooperative fishing, where dolphins assist human fishers by herding schools of fish into the shallows. The indigenous people of Minjerribah, also known as North Stradbroke Island in Australia, used to fish in association with dolphins. The fishers would be standing at the beach on the edge of the water holding their nets and spears while waiting for the fish at Amity Point. As soon as a school of fish approached, the fishers holding the spears would enter the water and start striking it with their spears as a signal for the dolphins to start herding the fish towards the beach. The other fishers would then rush in with their nets to catch the fish. Nowadays the Indigenous people of Minjerribah and other coastal areas of Australia perform a dance that tells this story – when their ancestors would go fishing in association with the dolphins.