Fish (Pisces, from the Latin piscis = fish) are aquatic vertebrates with gill breathing. The class of fish does not describe a self-contained class, as is the case with mammals, birds, amphibians, or reptiles, but summarizes a group of morphologically similar animals.
Geologically, the first fish appeared about 480 million years ago in the Ordovician. Today, biologists distinguish between 33,000 species of fish, and this number is constantly being revised upwards as new species of fish continue to be discovered.
In principle, two types of fish can be distinguished:
- Cartilaginous fish: Skeletons made of cartilage, e.g. shark and ray
- Bony Fish: Bone skeletons, such as salmon and catfish
Note: Even if the external shape or the habitat suggests it, whales, penguins, and dolphins are not fish.
Characteristics of the fish
The class of fish combines some characteristic features, including e.g. gill breathing, fins for locomotion and scales as protective armor. However, it can happen that individual fish species do not have all the characteristics listed here. The reason for this is the long phylogenetic development, in the course of which very different manifestations developed.
Fins: Fish use their fins to move.
Reproduction: Most fish species do not copulate. Eggs are fertilized in water.
Smell: By far the most developed sense in fish is smell. Fish perceive their surroundings poorly.
Gill breathing: Fish absorb the oxygen dissolved in the water through their gills.
Spawn: Fish hatch from eggs called spawn. There are also viviparous fish, but even with them the fish develop from eggs, albeit in the body of the fish.
Poikilothermy: All fish are cold-blooded. Your body temperature is essentially determined by the outside temperature.
Mucus Glands: There are mucus glands under the scales. The secreted secretion protects against bacteria and reduces frictional resistance in the water, allowing fish to swim faster.
Scales: The scale armor protects the fish from external mechanical influences.
Swim Bladder: All bony fish have a swim bladder. This allows fish to regulate the buoyancy in the water.
Lateral line organ: The lateral line organ is a special sensory organ used to perceive movements.
The corresponding sensory cells are located on the left and right side of the body.
Vertebrates: As vertebrates, fish have a spine.
List of fish
Eel, frogfish, brown trout, barbel, barracuda, blobfish, clownfish, cod, flounder, perch, trout, goldfish, guppy, shark, hammerhead shark, pike, cod, carp, dogfish, koi carp, puffer fish, salmon, mackerel, cottonflies, Sunfish, moray eel, piranha, burbot, coelacanth, rainbow trout, ray, redfish, anchovy, tench, plaice, swordfish, seahorse, turbot, sturgeon, tiger shark, tuna, catfish, walleye, electric eel.
Fish are aquatic vertebrates. Fish absorb oxygen through their gills.
The first fish appeared in the oceans 480 million years ago.
Approximately 33,000 known species of fish populate the seas and oceans. The actual number of species is likely to be much higher.
What is the most intelligent fish?
“It’s some of the best I’ve ever seen underwater.” Manta rays are considered very intelligent. They have the largest brains of any fish, and giant manta rays even passed the so-called mirror test in a 2016 study.
What is the biggest fish in the world?
Whale Shark: The biggest fish.
Do fish feel thirsty?
This process is called osmosis. The fish have to compensate for the loss of water: they are thirsty. They take in a lot of liquid with their mouths, they drink salt water.
Can fish drown?
No, it’s not a joke: some fish can drown. Because there are species that need to come up regularly and gasp for air. If denied access to the water surface, they can actually drown under certain conditions.
How is a fish adapted to live in water?
Instead of lungs, fish have gills. They are the most important adaptation to aquatic life. The gills allow the fish to move about in the water without having to come up for air on the surface.
How do fish sleep in the water?
Pisces, however, are not completely gone in their sleep. Although they clearly reduce their attention, they never fall into a deep sleep phase. Some fish even lie on their side to sleep, much like we do.
Are fish tanks cruel?
Not only does being held in captivity cause animals mental stress, it’s also physically damaging to the animals.
Is it ok to eat fish every day?
Fish is still recommended as a healthy food that everyone should ideally eat two to three times a week.
Is a fish an animal?
Fishes or pisces (plural of Latin piscis “fish”) are aquatic vertebrates with gills. In the narrower sense, the term fish is restricted to aquatic animals with jaws.
How do fish drink water?
Freshwater fish constantly absorb water through the gills and the body surface and release it again through the urine. So a freshwater fish doesn’t necessarily have to drink, but it does take in food along with water through its mouth (after all, it swims in it!).