Freeloader Fish

Jellyfish-fish commensalism often involves juvenile fish, such as young jacks or trevallies, that hide among the tentacles of large jellyfish species like Nomura's jellyfish (Nemopilema nomurai) or lion's mane jellyfish (Cyanea capillata).

These fish gain protection from predators that are deterred by the jellyfish's stinging nematocysts.

The fish exhibit specific behaviors, such as swimming just outside the jellyfish's tentacle range or mimicking its movements, to avoid being stung themselves.

This relationship is particularly beneficial in pelagic zones, where shelter is scarce.

While the jellyfish provides refuge and occasional transport, it does not gain any observable advantage, making this a classic example of commensalism.