yes
Native species of crayfish that are are a normal part of the ecosystem are not harmful. But there are several invasive species, like the rusty crayfish, that can kill off native crayfish and other crustacians. The rusty crayfish has a thicker shell and less "meat" and therefore are are not a good part of the food chain depriving the ecosystem of the nutrients from the crustacians it replaces. Invasive species also tend to destroy large amounts of water plants that further degrade the food chain. Also there is an infection that occasionally occurs in crayfish that can spread to other animals but this is usually a normal part of the life cycle and not neccasarily harmful.
Pandas are not an invasive species.
A noxious weed is another term for an invasive plant species.
Invasive species
The rusty crayfish (Orconectes rusticus) was first recorded in Ontario in the early 1970s. It is believed to have been introduced to the region through bait buckets used by anglers. Since then, it has spread and become an invasive species, impacting local ecosystems.
invasive
We try to stop invasive species entering our rivers and lakes.
Three species of crayfish are present in Finland, Astacus astacus (Noble grayfish), Astacus leptodactylus (Danube crayfish) and Pacifastacus leniusculus (Signal crayfish), for your question about 'Why?', I can't answer anything else than the climate and water conditions are suitable for these species of crayfish.
exotic species
No.To be an Invasive Species the animal must not be in the area before.Displace a species or multiple species from the area.Bald eagles do neither.
Yes, there are crabs in the Ohio River, specifically the invasive blue crab species. While they are not native to the region, they have been found in some parts of the river. However, the predominant crustaceans in the Ohio River are typically freshwater species like crayfish.
Some species of crayfish, such as the spiny lobster, are saltwater animals, while other species, such as the kabby or koura, are freshwater animals. It all depends on which species of crayfish you are referring to.