Fish: different types, definitions, photos, etc.
Fish are the oldest vertebrates, with a wide variety of species. There are about 32,100 named fish species distributed in various waters on the earth, of which there are about 2,500 species in China. Most of them live in seawater, with more than 1,500 marine fish and about 800 freshwater fish. In the past, fish were usually divided into two major categories, cartilaginous fish and bony fish, based on the similarities and differences in the properties of their bones. Characteristics: Aquatic animals (living in water). Skin covered with scales, belonging to cold-blooded animals. Cold-blooded animals with fins (can swim in water) and breathing with gills. Fertilization is external, mainly oviparous, some are viviparous and ovoviviparous.
Fish are a type of aquatic animals under the phylum Vertebrata, which mainly breathe through gills and use fins as the main organ of movement. Fish are the oldest and most diverse group of vertebrates on Earth, widely distributed in environments such as oceans, freshwater lakes and rivers.
Fish classification table
Fish can be divided into three major categories based on anatomical and physiological characteristics: cartilaginous fish (such as sharks), bony fish (such as carp) and jawless fish (such as lampreys). The following is a detailed list of fish classification:
| Classification level | Order | Family | Genus | Examples |
|---|
| Cartilaginous fish | Elasmobranchii | Carcharhinidae | Carcharhinus | White Shark, Blue Shark |
|
| Pristidae | Pristis | Sawfish |
|
| Rajidae | Raja | Yellow Spotted Skate |
| Jawless Fish | Cyclostomata | Petromyzontidae | Petromyzon | Lamprey |
|
| Myxinidae | Myxine | Hagfish |
| Bony fishes | Cypriniformes | Cyprinidae | Cyprinidae (Cyprinus) | Carp, grass carp |
|
| Siluridae | Silurus | Catfish |
| Perciformes | Percidae | Perca | Perch, largemouth bass |
|
| Moronidae | Morone | Seabass |
| Anguilliformes | Anguillidae | Anguilla | European eel, Japanese eel |
| Osteoglossiformes | Osteoglossidae | Osteoglossum | Dragon fish |
| Scombriformes | Scombridae | Thunnus | Tuna, bluefin tuna |
| Clupeiformes | Clupeidae | Clupea | Sardines, herrings |
| Characiformes | Characidae | Astyanax | Piranha, Astyanax |
Main evolutionary history of fish
1. Origin
Fish are one of the oldest groups of vertebrates on Earth, and the earliest fish fossils can be traced back to the Cambrian period. Jawless fish (such as lampreys and hagfish) are the most primitive fish, followed by cartilaginous fish (such as sharks) and bony fish.
2. Cartilaginous fishes
Cartilaginous fishes (Chondrichthyes) include sharks, rays, etc. Their skeletons are made of cartilage rather than hard bones. These fish play an important role as predators in marine ecosystems.
3. Bony fishes
Bony fishes (Osteichthyes) are the most diverse group of fishes, with a hard bone structure. They have adapted to a variety of water environments, including freshwater and saltwater.
4. Jawless fishes
Jawless fishes are the earliest fishes, and representative species include lampreys and hagfishes. They have no jaws and rely on suction or parasitism for survival.
Ecological role of fish
Important position in the food chain:
Environmental health indicators:
Resource Utilization:
Conservation Status of Fish
Overfishing: Many economic fish are facing the threat of extinction due to overfishing.
Habitat Loss: Pollution and water development have caused serious damage to fish habitats.
Climate Change: Temperature changes and acidified oceans are affecting the distribution and reproduction of fish.
Conservation measures:
Establish aquatic conservation areas.
Implement sustainable fishing policies.
Protect endangered fish populations, such as sturgeons and eels.
