1993). There are a number of other well-described examples where keystone species act as determinate predators. Sea otters (i) regulate sea urchin populations, which in turn feed upon kelp and ...

Urchins however are readily consumed by sea otters (keystone species), and by keeping urchin numbers low, otters assure that the kelp forest community remains intact. Bottom-up forces influence ...

Biologist Jim Bodkin, who studies the otters in Glacier Bay, says that "the otter is a keystone species, that it is a species that plays a pivotal role in its habitat. Scientists have been able to ...