intermediate host

An intermediate host is an organism that a parasite uses during its life cycle for asexual reproduction, but not sexual reproduction. This is in contrast to a definitive host, where sexual reproduction occurs.12

Parasitic organisms, particularly flatworms like flukes and tapeworms, often have complex life cycles involving intermediate hosts. For example, snails can serve as intermediate hosts for fluke larvae, which then develop further before potentially infecting a vertebrate host. In some cases, the parasite may even alter the intermediate host's behavior to increase the likelihood of it being eaten by the definitive host. Not all parasites require an intermediate host; some can complete their entire life cycle within a single host.3