In a subsequent paper, he designated the Pisaster starfish a “keystone species,” referring to an architectural keystone: the wedge-shaped stone atop an arch that, once inserted, prevents the ...

A keystone in an arch's crown secures the other stones in place. Keystone species play the same role in many ecological communities by maintaining the structure and integrity of the community.

exerting a strong influence over the occurrence and distribution of other species. In contrast, keystone species have effects on communities that far exceed their abundance. That is to say ...