Are Dolphins Whales? Deep Diving Into A Dolphin's Classification

Dolphins are known to be the most highly intelligent marine mammals that reside in waters and breathe air through the blowhole, which is placed on top of their head.

In total, there are about 36 species that belong to the dolphin family. You can find dolphins in almost all types of waters such as freshwater, coastal and estuarine.

The intelligent marine mammals, dolphins are small members of the Cetacea, which is an order for whales. These small cetaceans are known for their superb acrobats under specific conditions and have been trained to perform in ocean parks.

They are part of toothed whales that include other whales such as orcas and pilot whales. You’ll be surprised to know that dolphins have a life expectancy of more than 100 years in the wild.

Sometimes, the terms dolphins and porpoise are used in place of each other to refer to any member of the dolphin family. Three main families of dolphins have been recognized by scientists, river dolphins, South American river dolphins, and ocean dolphins. After reading all about these cetaceans, do check how do dolphins communicate and how do dolphins sleep?

Are dolphins and whales related?

Both whales and dolphins are mammals who are important members of the marine ecology. The number of similarities between them makes us forget the differences between them.

Dolphins and whales are related to each other, but not all dolphins are whales. This is because of the Cetacean sea order, which includes sea animals such as dolphins and porpoises, which we may think of as whales in general.

The order of Cetacea is divided into multiple different families, and Delphinidae includes all of the dolphins in the ocean waters.

The biggest member of Delphinidae is the killer whale. Killer whales are a dolphin and whales at the same time.

As whales and dolphins both belong to the Cetacean order, they are mammals who share the traits of being warm-blooded, having hair on their body, and the ability to breathe through their lungs.

The other similarities between dolphins and whales include fins on the tail, which are called flukes, bodies, which are streamlined for the purposes of swimming, and dorsal fins on their back in some cases. Both whales and dolphins share a common ancestor.

Difference Between Whales, Dolphins, And Porpoises

Quite often, people use terms such as whales, dolphins, and porpoises to refer to the marine animals of cetaceans. However, they are a lot different from one another.

Whales are categorized as baleen whales and toothed whales which are also known as Mysticeti and Odontoceti, respectively. The main difference between them is that toothed whales have one blowhole and teeth while baleen whales have two blowholes and baleen. The families of Delphinidae, oceanic dolphins, and Phocoenidae, porpoises are considered as members of the toothed whale family.

The term ‘whale’ is kept aside to differentiate the species based on their sheer size, as whales are generally more giant than their counterparts in the marine ecosystem.

Whales such as baleen whales, blue and fin whales, and sperm whales are the largest whales on this planet. The first major difference is the dorsal fins which are relative to the body size of these whales.

Bottlenose dolphin species have a dorsal fin that is well defined; meanwhile, whales do not possess the dorsal fin.

Whales have a neck vertebrate that is fused which is an adaptation that allows them to support the weight of their heads, whereas dolphins have flexible backs, which allows a quicker movement underwater.

Porpoises have a leaner body in comparison to dolphins. The whales of Mysticeti order possess baleen plates which result in their diet being a lot more different than a dolphin or porpoise’s diet.

Dolphins such as bottlenose dolphins will go after and prey upon squid and fishes, which these cetaceans can grab with their conical-shaped teeth; meanwhile, baleen whales such as humpback whales prey upon krill and copepods and kill them with their teeth.

Dolphins use echolocation for hunting their prey and navigating through the pacific sea or other oceans. Baleen whales use songs for communication and other purposes.

Dolphins tend to be chattier and make a range of sounds that can be heard by the human ear, whereas porpoises communicate at a frequency that is high and cannot be heard by human ears.

Dolphins are likely to have spade or cone-shaped teeth, whereas porpoises have flat, spade-shaped teeth. The structure of a dolphin’s blowhole is different from both porpoises and whales, which allows dolphins to make a variety of whistle sounds that are used for communicating with others.

The brain of a dolphin is relatively large to the body size of any animal, and they are highly intelligent. Killer whales have the second-largest brain of any animal on land or water; they only fall behind Sperm whales.

Dolphins and porpoises are social animals.

Dolphins travel in large groups or pods of animals who are related to each other, where they help each hunt their prey and play. However, porpoises tend to travel in smaller groups in comparison to dolphins and have a more subdued behavior.

This allows them to escape other predators such as killer whales.

Great whales are more solitary and are only seen in groups for the purposes of breeding or sharing a common food ground. There is a common misidentification between cetacean’s dolphins and porpoises, but they have a lot of differences.

Common species of dolphins that are mistaken for whales but are actually not whales include pilot whales and false fast killer whales. The study into the behavior of Cetaceans is still going on.

Species of dolphins such as bottlenose dolphins are known to have a friendly behavior; they can be found in regions that range from islands of Hawaii to Australia.

Some behaviors of baleen whales are associated with food aggression and mating. They are found in major oceans around the world, such as the Tasma Sea of Australia and the Pacific ocean.

Do dolphins have gills?

You might think that dolphins breathe through gills just like all fishes underwater, but that’s not the case. Dolphins and whales breathe like humans, by taking air into their lungs.

Even though dolphins live in the sea, they are mammals and are warm-blooded, unlike fish who breathe through their gills. Dolphins breathe through their nostrils which is called a blowhole.

This blowhole is located on top of their head. Blowhole allows a dolphin to breathe just by exposing the top of their head when they are swimming or resting.

After every breath, the blowhole is properly sealed by the muscles that surround the blowhole to make sure that water does not reach into the dolphin’s lungs. Whales generally have two blowholes; the only exception to this is a sperm whale, whereas dolphins only have one blowhole.

Both dolphins and whales have high amounts of hemoglobin and myoglobin in their bloodstream to store oxygen. They can reduce their heart rate and even turn off some organs when they are diving in order to survive in the deep sea.

Dolphins can hold their own breath for several minutes before they appear back on the surface.

Dolphins need to breathe four to five times every minute. There are some whales, such as sperm whales and Cuvier’s beaked whale, who can go hours between each breath.

A Cuvier’s Beaked Whale made a record when it dived for more than two hours without a breath; a land animal can never hold their breath for that time.

Dolphins have collapsible lungs, which allow them to breathe faster and quicker than humans. They can exchange up to 80% of the air which is inside their lungs with each breath, whereas humans can only exchange 17% of the air which is inside their lungs.

Why are dolphins mammals?

Even though dolphins swim in blue oceans and lakes, have a fish-like appearance, they are still classified as a mammal.

Vertebrate animals who possess mammary glands, hair, three bones in the middle ear, a diaphragm, are warm-blooded, and a lower jaw which is made up of a single pair of bones, are called mammals. Small Cetaceans and dolphin species such as bottlenose dolphins are considered mammals because they are warm-blooded.

Animals who are warm-blooded maintain a body temperature that is higher than the temperature of their environment. The ability to control body temperature is a characteristic of animals such as dolphins and whales.

According to science, being warm-blooded helps these animals avoid fungal diseases and infections. Dolphins breathe through their lungs, unlike cold-blooded animals such as fishes who breathe through their gills.

All mammals give live births, whereas reptiles lay eggs. Dolphins give birth to calves every two to four years. Mammals have hair, and the calves of a dolphin possess hair on their rostrum when they are born.

Dolphins do need hair to maintain their body temperature as they have rubber-like formations around their body to keep them warm. Marine animals who live on land and in water use fur or hair as a means of insulation.

Female dolphins have mammary glands, which is another characteristic of mammals. These mammary glands produce milk even while female dolphins are gestating, which means they can feed older calves while waiting for another calve to be born. The milk produced by dolphins is not the same as other animals though, the milk is low in lactose.

Do whales eat dolphins?

The killer whale relentlessly hunts down other dolphins. They are also referred to as ‘orcas’.

Even though killer whales belong to the family of dolphins, their overall size sets them apart from dolphins.

Orcas or killer whales can be 32 feet (9.7 m) long; meanwhile, the enormous baleen whale, which is the blue whale, can be as big as 100 feet (30.5).

In today’s time, if a dolphin is more than 30 feet (9.14 meter) long, it may be referred to as a whale. While baleen whales do not hunt down other dolphins or whales and only prey on krill and small fishes, killer whale is the only predator in the Pacific which regularly kills dolphins to consume them.

Killer whales are apex predators; they work in groups and even hunt other whales, such as sperm whales.

Dolphins tend to be faster than orcas, and it's not worth it for an orca to chase down a dolphin; however, if an orca does catch up to one, it will ram the dolphin in order to gain an advantage over it. Killer whales have a technique of chasing their pretty until it becomes exhausted.

Once the dolphin is exhausted, the orca will take it down.

Every day in the world, thousands of toothed whales and great whales underwater are accidentally killed by fisheries using fishing nets and ropes.

Fisheries are the main causes for death and harm for whales, dolphins, and porpoises.

Like humans, they must come to the surface to breathe as well and when they are caught in these nets, it is a race against time to reach the surface before they die due to suffocation.

In their attempt to escape, they get caught up in fisheries’ fishing gear and end up breaking their fins, teeth and tearing some muscles.

Those who end up breaking off from the nets of fisheries swim around for months with fishing gear wrapped around their bodies, which hurts their flesh and bones.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for are dolphins whales then why not take a look at what do dolphins eat?, or dolphin facts.