Urchins are an important indicator as to the biological health of many ocean eco-systems. Left unchecked, urchins will wreak havoc on kelp beds, reefs and other sub tidal areas leaving them barren by overgrazing on essential algae as well as more developed invertebrates. Important predators of urchins include sea otters, wolf eels and even humans for whom the urchin "roe" is considered a delicacy. Barring their predation, urchins have been known to decimate entire subtidal areas leaving them unable to sustain any but the most rudimentary life forms.