What are the main ways of alien species, and what is the difference between alien species and invasi

The difference between alien species and invasive alien species is that "invasive alien species" focuses on the adverse consequences caused to the local ecosystem; "Alien species" focuses on species that are not native and may have no impact on local ecosystems, may be detrimental or beneficial.

"Invasive species" is different from "alien species", it specifically refers to harmful alien species, such as the aforementioned "water hyacinth", "pine wood nematode", "rice grass", etc., and its scope is smaller than that of "alien species";

"Alien species invasion" is also different from "alien species introduction", which specifically refers to the process of invasive species spreading from their native places to invasion sites through natural or man-made routes, and damaging the biodiversity and ecosystems of the invasion sites and even endangering human health, resulting in economic losses and survival disasters.

An alien species is a species, subspecies or following taxa that occurs outside its past or present natural range and dispersal potential (i.e., cannot exist outside its natural range or without direct or indirect introduction or human care), including all its parts that may survive and reproduce subsequently, gametes or propagules.

The introduction of alien species is a concept closely related to the invasion of alien species. Any biological species always first forms in a specific place, and then gradually adapts to the natural living environment of the migration or introduction site through migration or introduction, and gradually expands its living range, this process is called the introduction of alien species (referred to as introduction).

Alien species include crayfish, water hyacinth, snails, Brazilian turtles, purple jasmine, cinchona, fetal squid, tilapia, etc. Crayfish: Crayfish are crustacean, decapod, crayfish aquatic animals.

Water hyacinth: Water hyacinth generally refers to phoenix eye blue. Phoenix-eyed blue floating water herb.

The fibrous roots are well developed and brownish-black. Fushou snail: Fushou snail is a mollusk of the family Bottle Snail and the family Bottle Snail.

The appearance of the shell is similar to that of a snail. It has a spiral shell, the color varies with the environment and the age of the snail, it is shiny and has several fine longitudinal lines, and the head and gastropods are protruding when crawling. <

Alien species include crayfish, water hyacinth, snails, Brazilian turtles, purple jasmine, cinchona, fetal squid, tilapia, etc.

1. Crayfish: Crayfish is an aquatic animal of the crustacea, decapoda and crayfish family. Also known as crayfish, crayfish, and freshwater crayfish.

It resembles a shrimp and has a hard carapace. The adult body is about centimeter long, dark red, the carapace part is nearly black, and there is a wedge-shaped stripe on the back of the abdomen. Juvenile shrimp are uniformly grey, sometimes with black ripples.

2. Water hyacinth: Water hyacinth generally refers to phoenix eye blue. Phoenix-eyed blue floating water herb. The fibrous roots are well developed and brownish-black.

3. Fushou snail: Fushou snail is a mollusk of the family Bottle Snail and bottle snail. The appearance of the shell is similar to that of a snail. It has a spiral shell, the color varies with the environment and the age of the snail, it is shiny and has several fine longitudinal lines, and the head and gastropods are protruding when crawling.

4. Brazilian tortoise: The Brazilian red-eared tortoise is a subspecies of the Brazilian tortoise of the family Ze Turtle and the genus Painted Turtle. The adult body is oblong, the dorsal carapace is gently raised, the ridge is distinct, and the posterior margin is serrate.

The head is broad, the snout is blunt, and the neck has yellow-green longitudinal stripes, and there are 1 long red patches on each side of the back of the eyes. The head and neck flanks and ventral surfaces are sandwiched with yellow-green linear strips.

5. Tilapia: Tilapia is native to Africa and is a tropical fish, with more than 100 species of tilapia, including subspecies. Tilapia has the characteristics of fast generation, high yield, miscellaneous diet, few diseases, and strong fecundity. Tilapia (African crucian carp) is the main aquaculture product in China.

A more typical example is the crayfish water hyacinth.