Fish and animals: the relationship and differences between the two

In nature, fish and other animals together form a rich and diverse ecosystem. Although fish live in water, mammals, birds, reptiles Most animals live on land or in the air, but both have unique characteristics in their physiological structure, behavior, and interaction with the environment. This article will explore the relationship and differences between fish and other animals to help readers better understand the relationship between fish and other animals. better understand their importance in the biosphere.

What are fish?

Fish are vertebrate animals that live in water and come in a wide variety of species, including freshwater and marine fish. Their main characteristics include gills for breathing, scale-covered bodies, and locomotion through fins. Fish are One of the oldest vertebrates on Earth, they have evolved for more than 400 million years. Fish are not just creatures that swim in the water, they play a very important role in the global ecosystem.

Main classifications of fish

Cartilaginous fish: This type of fish includes Sharks and rays have skeletons composed mainly of cartilage and their bodies are covered with skin rather than scales.
Bony fish: Bony fish are the most common fish. Their skeletons are made of true bones and their bodies are covered with scales. The gill cover can effectively protect the gills.

What is an animal?

Animals are a very broad group of organisms, including mammals, birds, Animals are more adaptable than fish, and can live on land, in the air, and in different water bodies. Animals often have complex behavioral patterns. , evolved diverse physiological functions, and interact with the environment in various ways.

Main classifications of animals

Mammals: Mammals feed their young through mammary glands, usually have hair-covered bodies, and can live on land, in the sea, or even in the air.
Birds: Birds are feathered vertebrates with light frames adapted for flight, although some species are flightless.
Reptiles: These animals are cold-blooded and rely on their environment to regulate their body temperature. Common examples include snakes, lizards, and crocodiles.
Amphibians: Amphibians, such as frogs and salamanders, have the dual adaptations of living in water and on land.
< p>Invertebrates: Invertebrates, such as insects, spiders, and shellfish, make up the vast majority of animal species on Earth.

Similarities between fish and animals

Although fish and land animals have many significant differences, they do have some important similarities.

1. All are vertebrates (most fish and animals)

Most fish and many animals are vertebrates, which means they have a spine made of bones (or cartilage). The spine provides structural support for the body and protects important parts of the nervous system.

2. Evolution of adaptation

For both fish and land animals, evolution is key to their survival and adaptation to their environment. Fish breathe through gills to survive in water, while land animals breathe air through lungs. At the same time, some fish and animals have evolved unique defense mechanisms, hunting techniques, and reproduction methods.

3. Diverse ecological roles

Both fish and land animals play important roles in their respective habitats. Fish help maintain the ecological balance of oceans and freshwater, controlling the number of plankton and aquatic plants. Animals help regulate ecosystems on land and in the air through food chains and competition between species.

Major differences between fish and animals

1. Breathing method

Fish breathe oxygen through gills, absorbing oxygen from the water, while most land animals breathe air through lungs. The structure of gills and lungs is completely different, adapted to the needs of their respective environments.

2. Movement method

Fish rely on fins to swim in the water, and their streamlined body structure helps them move quickly through the water. Land animals have evolved limbs or wings to help them walk, run on land, or fly in the sky.

3. Thermoregulation

Many fish are cold-blooded, meaning their body temperature changes with the temperature of their surroundings. Among land animals, mammals and birds are warm-blooded and can regulate their body temperature independently of changes in ambient temperature.

4. Reproduction

Fish reproduce in a very different way than mammals. Most fish reproduce by external fertilization, where the female lays eggs and the male releases sperm into the water for fertilization. Most mammals, on the other hand, reproduce by internal fertilization, where the offspring develop inside the mother and are born through childbirth.

Complementarity between fish and animals in an ecosystem

Although fish and land animals live in different environments, their interactions help maintain ecological balance. For example, birds such as seagulls prey on fish, and some mammals such as dolphins and sea lions also rely on fish as their main food source. On the other hand, fish indirectly affect the growth of terrestrial plants and the health of water quality by eating plankton and aquatic plants.

Some fish, such as salmon, have complex life cycles and swim back from the ocean to freshwater rivers to spawn. This behavior not only affects the continuation of fish populations, but also provides an important food source for animals along the way.

Fish and other animals together form a closely connected network in the biosphere. Although they live in very different environments and have different physiological structures and behaviors, their roles in the ecosystem are indispensable. By understanding the relationship between fish and other animals, we can not only better understand the complexity of nature, but also enhance awareness of biodiversity conservation.

Protecting the habitats of fish and terrestrial animals is a key step in maintaining global ecological balance. Only in this way can we ensure that future generations can continue to enjoy a rich natural environment.

Is fish an animal

Yes, fish are animals. Specifically, fish belong to the phylum Vertebrata, which is part of the kingdom Animalia. According to animal taxonomy, fish and other vertebrates (such as Fish belong to the kingdom Animalia, along with mammals, birds, reptiles, and amphibians. Here are some key points to explain why fish are animals:

Fish belong to the Phylum Vertebrata: Fish are vertebrates, which means they have a spine or skeletal structure. This is similar to other animals, such as mammals and birds, all of which All belong to the same phylum, namely the Vertebrate Phylum.
The basic biological characteristics of fish are consistent with those of other animals:

Cell Structure: Fish bodies are made up of animal cells, which have no cell walls, like all other animals.
Breathing: Fish breathe through gills (unlike mammals, which have lungs), but they still need to get oxygen from the environment.
Movement: Fish use their fins to move, and like other animals, they have specific ways of moving.
Reproduction: Most fish reproduce by laying eggs, similar to how many other animals reproduce.
Feeding and digestion >: Fish, like other animals, need food for energy and have a complex digestive system to digest food.

Therefore, fish are undoubtedly animals, and they are part of the animal kingdom just like mammals, birds, reptiles, etc.

The following is the classification of cartilaginous fish and bony fish and the comparison of some representative fish species:

Category	Cartilaginous fish	Bony fish
Bone structure	Made up of cartilage, bones are soft and flexible	True skeleton, made up of calcified bone, hard and stable
Skin structure	Skin is rough, covered with tiny dermal teeth, similar to sandpaper texture	Skin is smooth, covered with scales, scales can be renewed
Reproduction method	Most are oviparous or ovoviviparous, and a few species are viviparous	Mainly oviparous, and some species are ovoviviparous and viviparous
Buoyancy regulation	Maintain buoyancy by storing a large amount of fat in the liver	Regulate buoyancy by using the swim bladder (swim bladder)
Breathing method	The gill slits are directly exposed to the outside world and lack gill covers	The gills are protected by the gill covers and can effectively control breathing
Representative fish species	Sharks, rays, sawfish, hammerhead sharks, manta rays, etc.	Tuna, cod, carp, salmon, bass, mackerel, eel, tropical fish, etc.
Evolutionary history	The evolutionary history is even older, appearing about 420 million years ago	Appeared a little later, about 400 million years ago
Tooth structure	Teeth can be replaced continuously, and new teeth are gradually pushed forward from the back to replace old teeth	Teeth are fixed to the jaw and cannot regenerate
Other characteristics	Lack of swim bladder, must keep swimming to maintain buoyancy; can sense electric and magnetic fields to help hunt	Most bony fish have swim bladders to adjust buoyancy and can float in the water

Representative species of cartilaginous fish:

Sharks: such as great white sharks, tiger sharks, hammerhead sharks
Rays: such as manta rays, sawfish, electric rays
Sawsharks: such as Atlantic sawsharks

Representative species of bony fish:

Freshwater fish: such as carp, catfish, tilapia
Marine fish：such as cod, salmon, tuna, sea bass
Tropical fish：such as clownfish, angelfish, seahorse

Some fish contain toxins that are potentially dangerous to humans. However, many poisonous fish can be safely eaten if handled in certain ways. Here are some common poisonous fish and details on whether they are safe to eat:

1. Pufferfish (Fugu)

Source of toxicity: Pufferfish contains highly toxic tetrodotoxin, which is mainly concentrated in the liver, ovaries, skin and internal organs.
Is it edible: It can be eaten, but it must be processed by professional chefs. Especially in Japan, pufferfish is regarded as a delicacy, but it must be processed by qualified chefs, otherwise it will cause fatal poisoning.

2. Stonefish

Source of toxicity: The dorsal fin of the stonefish has a venomous spine, and the toxins secreted can cause severe pain and even be fatal in severe cases.
Is it edible: It can be eaten, but it must be handled with care and can be cooked after the venomous spines are removed. Stonefish has delicious meat and is especially used as a food ingredient in Southeast Asia.

3. Lionfish

ToxicitySource: The dorsal spines of lionfish contain toxins that can cause pain and swelling.
Is it edible?: It is edible. After removing the spines, the meat of lionfish is white and tender and tastes good. It has become a food in some areas (such as the Caribbean Sea) and has ecological significance for controlling alien species.

4. Stingray

Source of toxicity: Stingrays have venomous spines at their tails that secrete toxins, which can cause severe pain and other symptoms when stung.
Is it edible?: It is edible. After removing the tail spines, the meat of the stingray is a common ingredient in some delicacies, especially in Southeast Asia and the Mediterranean.

5. Blue-Ringed Octopus

Source of toxicity: The blue-ringed octopus contains tetrodotoxin, which releases venom through its bite. Its toxins can cause respiratory failure and even be fatal.
Is it edible?: Not recommended. Although the blue-ringed octopus is small and rare, it is not usually listed as a food source due to its extremely strong toxicity.

6. Certain types of triggerfish

Source of toxicity: The internal organs of some types of triggerfish contain toxins.
Is it edible: Some types are edible, but the meat of some types of triggerfish may carry Ciguatera toxin, which may cause poisoning to humans if consumed. Cooking cannot eliminate this toxin, so it must be carefully selected and handled.

7. Some types of sailfish

Source of toxicity: Some types of sailfish and large predatory fish may carry ciguatera toxin.
Is it edible: Some species are edible, but due to the possibility of toxins, it is recommended to be eaten with caution, especially in tropical and subtropical areas.

8. Some types of mackerel

Source of toxicity: Mackerel may contain scombroid poisoning, especially if the fish is not properly stored.
Is it edible: It can be eaten, but it needs to be freshly cooked and properly handled. Spoiled mackerel can cause allergic reactions or poisoning.

9. Surgeonfish

Source of toxicity: Surgeonfish may carry ciguatera toxin.
Is it edible: Some species are edible, but fish species carrying toxins have the risk of poisoning, so it is recommended to be eaten with caution in certain areas.

10. Snapper

Source of toxicity: Snappers in some tropical areas may contain ciguatera toxin.
Is it edible?: It is edible, but snappers caught in tropical waters should be avoided, especially those that live near coral reefs.

How to safely eat poisonous fish:

Rely on professional handling: Some poisonous fish (such as pufferfish) must be handled by professional certified chefs. Only chefs who are familiar with their internal organs, the location of toxins, and handling techniques can ensure safe consumption.
Avoid eating specific parts: Many fish have toxins concentrated in the viscera, fins, or skin, such as the spines of stonefish and the internal organs of pufferfish. After removing these poisonous parts, the fish meat is usually safe to eat.
Know where the fish was caught: Ciguatera toxins are commonly found in tropical and subtropical coral reef fish, and it is recommended to be extra careful when eating fish from these areas.
Ensure fish freshness: For fish that are prone to histamine toxins, such as mackerel, it is important to ensure that the fish is fresh and the cold chain is intact to avoid poisoning.

Some fish may pose a threat to humans in their natural state due to the toxins they contain, but many poisonous fish can still be made into delicious delicacies through professional handling, removal of toxic parts, or avoiding eating certain species. Safe eating methods include relying on expert handling, choosing reliable suppliers, and understanding how the fish is caught and stored.

How many types of marine fish and freshwater fish are there?

1. The number of species of marine fish and freshwater fish

Marine fish (saltwater fish): There are approximately 15,000-20,000 species of marine fish in the world's oceans, although the exact number may change as new species are discovered. Marine fish live in There is extremely rich ecological diversity in various marine environments, from shallow sea to deep sea, coral reefs to ocean trenches.
Freshwater fish: Global freshwater There are approximately 14,000-18,000 species of fish. Although freshwater only accounts for about 2.5% of the Earth's surface, freshwater fish species are very diverse and are mainly distributed in freshwater ecosystems such as rivers, lakes and wetlands.

2. The most abundant fish

The most abundant fish among marine fish

Anchovy: Anchovy is one of the most abundant marine fish in the world, especially in Widely distributed in the Pacific, Atlantic and Mediterranean. Due to their rapid reproduction and schooling, anchovies are widely used in fisheries and processed foods.
Herring ( Herring: Herring is also a large marine fish, especially in the northern Atlantic and Pacific waters. Herring live in large groups and have become one of the important economic resources in the global fishery.

The most abundant freshwater fish

Carp: Carp is one of the most widely cultivated and distributed freshwater fish in the world, and is particularly popular in Asia. Carp are diverse and highly adaptable, and are a key component of many freshwater ecosystems. Tilapia is a common fish in the world.
Tilapia: Tilapia is also a large number of freshwater fish in the world, especially They are widely farmed in tropical and subtropical regions. Their rapid growth and strong adaptability make them an important species in aquaculture.

There are about 15,000 to 20,000 species of marine fish and about 14,000 to 18,000 species of freshwater fish in the world. Marine fish include anchovies and herrings, while among freshwater fish, carp and tilapia are the most numerous and play an important role in aquaculture. These fish not only have a wide ecological distribution, but also play a key role in the human food supply chain.

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