Fish is the oldest marine animal and has been in the water for 500 million years. The total number of living Fish is greater than the total number of all the vertebrates living on Earth. The Fish term is used to refer to the diverse aquatic animals including Sharks and Finned ray fishes.
All Fishes share two same characteristics: they are vertebrates, which means they have vertebrae to protect the spinal cord and they live in water. Apart from these two shared similarities, many species in this group have different characteristics from each other.
In this comprehensive guide, we will explain the below-mentioned details:
- What is a Fish?
- Are Fish Animals?
- What Defines Mammals?
- Are Fish Mammals?
- Are Sharks and whales Mammals or Fish?
- Quick Facts About Fish
- Bottom Line
What is a Fish?
Fish belong to the subphylum Vertebrata, which live in water and have fins on their skin. The Fish breathe by taking the water through their mouths. They are colored animals and can even change their colors to attract mates. They have a length of less than 10mm to 20m. The body of mostly Fish is made up of bones. However, the body of a few Fish like Sharks is made up of a soft substance called Cartilage. They flap their tail to swim in the water and have scales to protect their body. Fish is divided into the following three classes:
- Agnatha: Jawless Fish
- Osteichthyes: Bony Fish
- Chondrichthyes: Cartilaginous Fish
They live in the ocean, rivers, and lakes, from the deep sea to the surface of the ocean and on all continents. They feed on underwater plants and other marine animals. The Cyprinid Fish is the smallest and the Whale Shark is the largest Fish worldwide.
Are Fish Animals?
The animal kingdom is divided into different phyla and subphyla; the several categories of the animal kingdom include mammals, fish, birds, amphibians, reptiles, and invertebrates.
Yes, Fish are aquatic animals, and they are the first known vertebrates on our planet. They are highly developed animals with developed nervous systems and reproductive systems. The classification of Fish is as follows that shows they are animals:
- Kingdom: Animalia
- Phylum: Chordata
- Sub-Phylum: Vertebrata
What Defines Mammals?
The warm-blooded animals that have a backbone and breathe air are placed in the class Mammalia of the animal kingdom. The mammals are subdivided into three groups: Placentals, Monotremes, and Marsupials. The Mammals have diverse groups, present on the land, and in fresh water and some have the ability to fly like bats. The total number of known marine mammals is 128, it includes Whales, Sea Otters, and Sirenians.
The mammals have hair or fur covered bodies and they secrete milk to feed their offspring. The other major characteristics of Mammals are listed below:
- They all are vertebrates; they have a backbone.
- They have four limbs.
- Mammals have sweat glands on their skin.
- They have specialized brains.
- Mammals have a unique jaw structure.
Are Fish Mammals?
No, Fish are not Mammals, they are two distinct groups of animals; they share some similarities, but they have few differences. Fish and animals both are vertebrates and have the ability to evolve to survive in their respective environments.
The Fish are not considered Mammals, because of the various below-listed reasons:
- Fish belong to the taxonomy group of Chordate and Mammals belong to the taxonomy group of Mammalia.
- Fish are cold-blooded animals whereas mammals are warm-blooded animals; this means Mammals can regulate their body temperature, whereas Fish depend on external sources to regulate their body temperatures. However, some sharks and other species of tuna have exceptions.
- The mammals have fur and hair, while Fish have scales.
- Fish cannot breathe air as they do not have lungs, though Lungfish and Snakehead are exceptions.
- Fish do not nurse their babies, but they lay eggs, on the other side Mammals give birth to live young and feed their young ones with milk.
- Fish are adapted to live in water and mammals are adapted to live in water and land.
- Fish are solidarity species, whereas Mammals prefer to live in groups and are highly social creatures.
Are Sharks and Whales Mammals or Fish?
Whales are warm-blooded and breathe air like humans do. Whales, Dolphins, and Seals are Mammals, but they are not Fish, because these species have lungs to breathe and nurse their young with milk. In contrast, some Sharks also give birth to fully developed live young, but Sharks are Fish.
The Skeleton of Sharks consists of Cartilage, a type of strong but soft tissue. The Sharks are covered with sharp toothlike scales called denticles whereas the fish are covered with smooth scales.
Quick Facts About Fish
Fish are fantastic creatures with diverse social behaviors and emotions. Below we have listed the fast facts about Fish:
- There are approximately 30,000 species of Fish and they are more in numbers than the total number of vertebrates on the Planet.
- In Fish, there is a special row of sensory scales known as the Lateral Line, to sense the nearby movements in the water.
- Depending on the needs, environment, and time of year, Fish can change colors.
- Fish use their gills to breathe, the gills are present on the side of their bodies.
- Fish are fast swimmers; the most common fastest Fish is Sailfish.
- Fish are flexible and adaptable; they have the ability to live in all sorts of waters.
- Fish can grow up to 12m long and weigh about 18.7 tons. The Whale Shark is the heaviest fish.
- The only Fish with eyelids is the Shark.
- The average brain of a fish is 1/15th the size of the brain of a mammal or bird.
- Some Fish are known as Clean Fish because they eat the flesh of other Fish or parasites to clean the water.
Bottom Line
Mammals and Fish are two distinct groups of animal kingdoms. The Fish are cold-blooded animals, and their bodies and fins are covered with scales. These species pass the water through their gills to breathe. On the other side, Mammals are warm-blooded animals and have fur and hair on their bodies. These vertebrates have specialized organs to respirate known as lungs.
The Fish is the most diverse group of vertebrate species, and it belongs to phylum Chordata, subphylum vertebrata, and is classified into three classes: Agnatha, Chondrichthyes, and Osteichthyes. Fish can adapt to the surroundings changing the salinity of water, temperature, and depth.
