One of the most asked questions about whales and fish is they are the same, and if not, how are they different from one another. First, let’s clarify the fact that whales are not fish; they are marine mammals. In fact, whales are very different from fish in several ways.
Physiological differences between fish and whales
Marine mammals such as whales can be classified as animals that rely wholly or partly on the ocean or coastal waters for survival while sharing many of the same characteristics of land mammals such as breathing air, being warm-blooded, and giving birth to their young.
On the other hand, Fish can be classified as a primarily cold-blooded, egg-producing, gill-bearing species that lacks any limbs with digits and does not require air to breathe. This quick classification clearly identifies several distinct differences between fish and marine mammals, such as whales.
For instance, whales are warm-blooded, while (almost all) fish are cold-blooded. Due to these mammals’ warm-blooded nature, they often require large amounts of food to maintain their energy and body heat.
To obtain enough food to power their large bodies, a whale’s diet often consists of fish, krill, squid, crustaceans, and other small aquatic life forms that give it the energy it needs to thrive and survive in the ocean.
A few species, such as the killer whale (these marine mammals are actually dolphins), will consume large marine mammals such as seals, sea lions, penguins, marine birds, dolphins, and even whales.
However, the diet of fish consists of larvae, smaller fish, squid, and plankton, among other small and microscopic organisms.
Whales also have a thick layer of blubber to keep them insulated in the cold Arctic and the Antarctic weather; in fact, some whale species have blubber that can measure up to 10 inches thick!
Rather than having blubber or body fat, fish are generally thin. They can naturally adjust to the temperature changes as they do not need to maintain their body heat the way warm-blooded mammals do.
Another strong distinction between fish and marine mammals involves breathing and how the respiratory system works between the two animal species. Fish have gills that extract oxygen from the water and allow it to live underwater their entire lives.
On the other hand, whales do not have gills but instead have one or two blowholes that connect to their lungs, which allow the whale to breathe in air. Due to the presence of lungs and the lack of gills, whales cannot extract oxygen from the water and must come to the surface for air.
In fact, while it’s possible for a whale to drown underwater, stays submerged for too long, or takes water into its lungs, it is also possible for a fish to suffocate above the water because it lacks the lungs or organs necessary for breathing in air.
Bone structure, swimming, and giving birth
Aside from these interesting facts, other physiological differences are apparent in the bone structure of whales. Whales are believed to have evolved from land-dwelling animals into inhabitants of the sea over the course of millions of years.
The design and curvature of a whale’s spine resemble a design that appears to have been used for running instead of swimming originally. When whales swim, they create propulsion by moving their tail and flukes up and down.
When fish swims, their spines are designed to move from left to right, and (in most cases) their bodies are streamlined for quick movement and turning in the water.
Whales (unlike fish) also have bones in their flippers, which closely resemble their land-dwelling ancestors’ limbs and digits and were believed to have been used to walk the earth millions of years ago. This also explains why whales are warm-blooded and breathe the air because their ancestors were originally designed to do so.
Here’s a recap of the differences between marine mammals such as whales, dolphins, and porpoises and the many different fish species, which also includes sharks:
Whales are warm-blooded, breathe air, give birth to live young (they have a pregnancy/gestation period), and produce milk to feed their newborns.
Fish (including sharks) are primarily cold-blooded, extract oxygen from the water through the use of gills, lay eggs (most species lay eggs externally), and some newborns get their nutrients from a sack that they carry around when first born rather than being fed milk the way newborn whales are. Lastly, there are large differences in how these two animals are nurtured.
Nurture versus nature
In many cases, whales, dolphins, and porpoises are cared for by their mothers for several months to several years and fed milk during their first year to make sure they grow up healthy and hunt and survive independently. Most species of fish, however, aren’t known for providing such care to their young.
In fact, after birth, many fish species are left to fend for their own and must rely on the sack that’s attached to them at birth for the nutrients they need until they can hunt and survive on their own.
For most fish species, there is no strong relationship between mother and child, especially since some fish can lay thousands of eggs over the course of a year.
Some scientific researchers may conclude that it is more important for these animals to lay massive amounts of eggs than caring for a single offspring. Part of the reason for this is the fact that large amounts of fish can be consumed in a relatively quick amount of time.
In fact, some whales can consume thousands of fish daily; therefore, the best thing a fish can do is create lots of offspring to maximize its chances of passing its genes on to the next generation. Some offspring will die. Naturally, some will get eaten, and others will live on long enough to reproduce and continue the family legacy.
Conclusion
In conclusion, many factors differentiate whales from fish. Whales are warm-blooded, oxygen-breathing marine mammals that give birth to their young and nurture them with milk and care, while fish are cold-blooded, gill-bearing animals that lay eggs often leave their children to fend for themselves after birth.
Because whales are typically larger than fish and are warm-blooded, they are likely to consume larger quantities of food than fish to maintain their blubber supply and provide their body with enough calories to survive and thrive in the ocean.
From an evolutionary standpoint, whales appear to have evolved from land-dwelling animals that walked and hunted on the land, which can be seen by observing the differences between whales and fish’s bone structure.
These distinct differences between whales and fish have led to very different classifications for these two types of animals. The examples given here clearly prove that these two animals are not the same.