Here's why:
* Biological vectors are living organisms that transmit pathogens from one host to another. Examples include mosquitos carrying malaria or ticks carrying Lyme disease.
* Lampreys are parasitic fish that attach themselves to other fish to feed on their blood. They don't carry pathogens in the same way that vectors do.
However, lampreys can be considered intermediate hosts for some parasites. For instance, the sea lamprey can carry the larval stage of a nematode worm (a type of roundworm). This worm can then infect other fish when the lamprey feeds on them.
So, while lampreys themselves aren't vectors in the strict sense, they can play a role in the life cycle of certain parasites, acting as intermediate hosts.
