Whale Anatomy

When it comes to the anatomy of marine mammals whales, dolphins and porpoises all share several common and unique characteristics that allow them to survive and prosper in the various oceanic environments they can be found living in.

Like other mammals these marine animals require oxygen to breathe, eyes to see, ears to hear and mammary glands to feed their young among other things.

Unlike other mammals however whales, dolphins and porpoises have flippers, flukes, a dorsal fin and blowhole(s) that make navigating the ocean much easier.

They also possess blubber and the ability to shut down non essential functions when diving in order to stay warm and maximize their ability to hold their breath for extended periods of time.

This article will give you a basic understanding of a cetaceans anatomy and help you understand why these physical adaptations are so important for their survival.


Whales, porpoises and dolphins are  marine mammals and like all mammals they require oxygen to survive.

Unlike other sea creatures such as fish which use gills to extract oxygen from the water whales must come to the surface to breathe as they possess lungs and a blowhole rather than gills.

The blowhole is situated on or near the top of their head and acts as an airway passage for breathing.

Surprisingly whales cannot breathe through their mouth like humans and most land based mammals because their esophagus (food passage) and trachea (air passage) are completely separated from each other.

Although whales breathe air they can spend up to 90% of their lives underwater.


There are two primary whale suborders that are divided based on their physical characteristics.

The first of these two suborders is the toothed whale suborder.

Toothed whales are typically smaller than their baleen whale cousins and have a single blowhole on their head as compared to the two blowholes found on a baleen whale.

In order to capture their prey, chew their food and protect themselves against threats these marine mammals possess teeth.

The number of teeth they posses can vary greatly among each of the species, and some species may not use their teeth for eating.

Some whales such as the sperm whale are believed to use their teeth mainly to show aggression while other species use their teeth only to grab onto their prey and swallow their food whole.

Killer whales are known to use their teeth for everything from biting and wounding their prey to defending themselves when hunting for sharks.

Instead of enamel which is found on the teeth of humans humans a whales teeth is covered in cementum cells and unless the cementum is worn down you won’t be able to see the enamel on their teeth.


Baleen whales are the other suborder of the toothed whale species.

Baleen whales are generally larger than toothed whales and have rows of baleen plates with bristles that resemble the teeth of a comb located on the top of their jaws instead of teeth.

The bristles act as a filter allowing water to escape their mouth while being packed tightly enough to keep fish and crustaceans trapped inside.

Because these large marine mammals do not possess teeth they end up swallowing their food whole so they frequently hunt for small manageable prey that is easily consumable and tend to look for large swarms of fish, squid or krill to consume.

In order to capture their prey baleen whales swim towards their prey with their mouth open and use their baleen as a net to capture as much prey as possible.

They then push the water out of their mouth and swallow their food whole.

Dorsal fin

The main purpose of the dorsal fin is to stabilize the whale and keep it from rolling in the water.

Dorsal fins can vary greatly in terms of shape and size depending on the species of whale and while many species possess a dorsal fin there are some exceptions such as the sperm whale and beluga whale which have no dorsal fin at all.

Some species of dolphin and porpoise also lack the presence of a dorsal fin.


The flippers on a whale or dolphin are used to navigate and steer in the ocean.

These marine mammals use their flippers to perform various aquatic acrobatics such as steering left and right by changing the angle of their flippers and use their flippers to provide lift so they can rise in the water and control their level of aquatic depth.

The flippers are controlled by strong pectoral muscles and can vary in size with each species.


The flukes are attached to the end of the whale/dolphin and are used for propulsion.

Unlike sharks however whales and dolphins move forward by flexing their tail up and down, not left and right.


The eyes of a whale are relatively small when compared to the rest of its body.

Their eyes are well adapted to aquatic life and secrete an oil used to lubricate and protect their eyes from debris and other chemicals in the ocean.

While it is possible to secrete oil whales are not capable of secreting tears, but their cries can often be heard from many miles away.


The ears of a whale or dolphin are designed differently than a humans ears and are well adapted to marine (aquatic) life.

For a whale/dolphin there is little difference between the inner and outer ear area.

Instead of receiving sound through the outer ears whales receive sound through their throat, the sound than passes through a cavity and into the inner ear.

Some whales also use echolocation to navigate the ocean and rely heavily on sound to observe their surroundings.


Because whale are warm-blooded they need to be able to maintain their body heat.

One of the ways they do this is to form a thick layer of insulated blubber around their body which acts as a heat insulator and moderator.

The thick blubber helps keep the cold/freezing temperatures of the outside water away from the whales vital organs and can even protect whales against attacks from predators such as sharks and killer whales.

Differences between whales and fish

Given the fact that whales and fish inhibit the ocean together it’s easy to assume that they share some close physical characteristics with one another, however this is not the case.

In fact in some ways whales and fish are like night and day when it comes to how they live and thrive in the ocean.

For instance whales possess a thick layer of blubber to keep their vital organs warm in the cold/freezing water.

Fish on the other hand are cold-blooded and do not have to manage or regulate their internal body heat in order to survive.

Another major difference between whales and fish is the fact that whales breathe air and must rise to the surface of the water to obtain oxygen while fish extract oxygen directly from the water.

While whales go through a pregnancy phase and give birth to their children many species of fish lay thousands of eggs and leave them to hatch on their own.

Here are several characteristics that show some of the major differences between whales and fish:


  • Are warm-blooded
  • Breath air
  • Give birth to their young
  • Produce milk


  • Are cold-blooded
  • Extract oxygen from the water using gills
  • Lay eggs
  • Aren’t known for nurturing their young
Note: Whales can vary greatly in terms of weights and size. The dwarf sperm whale for example only grows to a length of about 9 ft. and weighs up to 600 pounds while the blue whale can grow to over 98 ft. and weigh up to 150 tons!