Fish Adapting

Fish are classified as aquatic vertebrates that have existed for long years. The mixture of their gills, scales, and the fact that they live only in water makes their trait different from all other animals.

They are adapted to travel effectively under the water and have a good sense of their surroundings.

Different characteristics and features of fish also evolved from time to time to help them avoid predators. They can also live suitably in the water environment and acquire all their needs to survive.

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Fish anatomy adapts to allow other species of marine life to thrive in their habitats. Like many animals, they have adapted to live depending on their types of chosen habitats.

For example, giant water bodies like saltwater in some lakes and rivers regions. According to studies, there are over 160 species of fish, each with its own unique and distinct characteristics and capabilities.

What Is Adaptation?

Adaptation is a process of change. It takes place over a long time and may even occur for millions of years through natural selection.

These changes will affect all organisms and life forms, and they can change not just their physical attribute but also their mental behavior. Some life forms undergo a specific change to fit in their environment.

This is a critical process in the upbringing of an organism. If they failed to evolve over a long period and still didn’t get fit in a chosen environment, they would eventually become extinct.

Habitat is the surroundings or environment an animal or plant decides to live in. When it changes, an organism that can adapt will most likely survive.

In the natural selection process, the changes in their physical attribute and mental behavior that adapted well to a particular habitat will be kept or passed on to the next generation of an organism. Sometimes it evolves and changes over time depending on their needs.

Adaptive Features Of A Fish

Fishes are prime examples of these adaptations because they show many changes over a long period of time to help them survive and avoid predators in the water environment.

Most physical changes appeared in their mouths, gills, body shape, color, senses, and locomotion. These fundamental changes are vital in their habitats for them to survive.


Fish have gills. A gill is part of aquatic organisms’ anatomy that takes oxygen from the water and excretes carbon dioxide. Like any living life form in this world, fish need a supply of oxygen to breathe and survive.

The gills of a fish consist of many slits, not more than eight, to help them breathe underwater. These slits connect the pharynx to the outside on the other sides of the fish head.

As fish swims in the water, they open their mouth, and water passes from them directly into the gills. As we know, water consists of oxygen.

The oxygen in the water passes through the thin layers of gills and goes straight into the blood supply, giving them enough oxygen to flow through their body.

Oxygen in water only consists of 4 to 8 parts per million; this is way off compared to the ones present in the atmosphere, which is about 20% capacity.


Fish go on a daily changing their color for an extended period. It’s one of their skills and tactics to help them avoid such predators. It’s one of the proofs that natural selection does happen.

One good example of this is fish do have multiple colors depending on where you’re looking at them. They usually are dark at the top of the water and light at the bottom. It is called countershading.

One unique skill they possessed is called camouflage. This is a process where they adapt their whole body to blend in and hide from their predators. For example, pickerels and bluegills have some vertical stripes on their body to help them hide in vegetation and corals.

They also used this skill not just to avoid predators but also to hide from their prey. Fish can be both prey and predators at the same time.

Another skill that they adapted over time is changing their body’s color patterns and texture. This helps them attract a mate and gives them a better chance of reproduction. Variation of patterns also can be used to identify if the marine species is a male or a female.


Fish has changed and adapted its mouth over millions of years. This developed over time as they changed their needs depending on their habitat. Freshwater fish mainly eat insects or larvae with different mouth anatomy than fish from the saltwater habitat.

One good example is walleye; they have a huge jaw with a robust and elaborate set of teeth to help them catch their prey. Some fish don’t have teeth, just a round vacuum-like structure of their mouth.

These fish suck up all organic and algae materials from the bottom or up the surface of a swamp or stream.

Body Structure

The shape of the body can also be considered an adaptation and evolution for fish species as it is one of the essential adaptations a fish may go through.

This is helpful for many marine species, especially those with an elongated body; this helps them swim and move through the water efficiently.

Many fish, with their agility, developed a spine that predators may have issues with when they try to attack. Others have thin bodies where they can hide in narrow and tight spaces to avoid getting eaten by predators and be predators to prey upon others.

They also adapt their fins; their location and shape vary from one another. The general anatomy of fish consists of a dorsal fin located on their back and pelvis and anal fins on their undersides.

They also developed pectoral fins near their gills and a caudal fin located in their tail. These fins can be eminent parts of the body structure. They developed depending on their needs. The texture and size of their scales rely on how they adapt to their environment.

Sense Organs

Humans rely on their sense of sight, and it is one of the essential parts of everyone’s senses. This is also very important to marine life forms as light does not penetrate or reach even the bottom and depths of the ocean.

This is why they developed a rare and very distinct sense of smell. They have more sensitive noses than humans.

For example, you’ve seen some movies about sharks that we can detect even a slight amount of blood in the water. This is because they developed such a distinct array of smells using these sensory pads to know danger over some time.

Some of the species developed a sense of vibrations in the water.


The ideal structure of a marine fish is somehow streamlined to how it moves. Most fishes, for example, a Trout or a Minnow, can swim in water for approximately ten body lengths per second; this is an impressive quality and performance any fish can do to human standards.

Trout can swim only about 10.4 kilometers per hour. But if you think about it, these speeds can be roughly translated into kilometers per hour. It means that 30cm is equal to 1 foot. Again, as a general rule, the bigger the fish, the faster it can swim.

Animals like whales and dolphins share a similar structure to a fish but evolved more from the non-aquatic animals; they resemble fish. Depending on their bodies, their agility relies on their ability to move in the water. It is called convergent evolution.

It is an evolution of similar structures and organisms but unrelated species in the same environment. Evolutions of fish rely more on how they can swim rapidly in water.

Some fish that don’t travel or migrate tend to have a rounded tail for quick acceleration and stop.


Fishes are adapted to move precisely and sense their habitat under bodies of water. They evolved to meet their needs and be able to help them survive for another day.

Overall, life finds its way whether you’re a marine life form or just a human being. It’s natural selection, a natural process that will continue and evolve.

Many fishes and all marine species do evolve for the same reason, survival. You might either be left out and become extinct or move on and go with the life cycle process.