What does each partner gain?

Look at the three cards. For each pair of animals, ask what each one gains and what the encounter costs it.

Start with the same question for every encounter: what changes for each animal?

Three outcomes to compare

1

Mutualism

Both partners benefit.
2

Commensalism

One benefits and the other is largely unaffected.
3

Parasitism

One benefits by taking resources from a host that bears a cost.

When the cleaner takes mucus

The client can interrupt the visit. The option to leave helps explain why taking mucus can cost the cleaner a meal.

A cleaner wrasse eats small parasites off the fish that visit its station. Experiments show it can prefer the fish’s mucus to some parasites. If the wrasse bites into that protective layer, the visitor can break off the cleaning and may go elsewhere.

The fish that keeps watch for two

Watch the goby at the burrow entrance. It spots danger while the shrimp moves sand. An antenna touching the fish lets the shrimp feel its movements. The goby gains access to the shelter the shrimp digs.

A goby watches a burrow entrance as a shrimp moves sand.
The shrimp digs a burrow and the goby watches the surroundings. The shrimp maintains the shelter while the goby detects danger and signals it through movement. © dive.explo360.fr — All rights reserved. Reproduction requires permission.

Continue reading

AMIGANSEAU CONTENT

The rest of this article is for subscribers

Log in with your AMIGANSEAU licence to continue reading.

Discover licences
All active AMIGANSEAU licences give access to the full article.

Continue exploring

Also discover

Way of life · BehaviourLearning and solving problems underwater 6–10 years 11–14 years 15–17 years Adults (18+) Read article →