Zoology · Ch 11 — Organisms and Population
Commensalism
Commensalism
Commensalism, scored (+, 0), is the interaction in which two or more species are associated in shared activities — most often centred on food, though the concept has been broadened in recent years to also cover shared cover, support, or even shared locomotion — such that at least one species, the commensal, benefits from the association while the other associate is neither helped nor harmed by it. The chapter's examples are barnacles that attach to whales and are carried thousands of miles while filtering food from the passing water, with the whale entirely unaffected by their presence; egrets that stay near grazing cattle to catch the insects the cattle disturb as they move, benefiting the egret while leaving the cattl …
What this figure shows. A two-part illustration of commensal partnerships. In the first part, cattle grazing in a field are shown with egrets walking alongside or perched near them, catching insects that are stirred up and disturbed by the cattle's movement through the grass, illustrating that the egret gains an easy food source while the cattle experience no benefit or harm from the birds' presence. In the second part, a whale is shown with clusters of barnacles attached to its skin, illustrating how the barnacles are carried passively across thousands of miles of ocean and filter-feed on food particles from the water the whale swims through, while the whale its …