Empty habitat is called an Urchin because;
The urchin barrens have a relation to the places where a sea urchin species population marked a drastic increase up to a state where the urchin species then start the destruction of everything in it's path of growth ad therefore leaving behind a barren land.
These Urchin barrens are clustered with Urchins that are good sources is food for the sea otters.
They are also good for the killer whales at some other places are also sea otters.
These killer whales love to feed in Sea otters and the urchin barrens are the best place for one to find sea otters.
For those killer whales,it is is actually easier to find sea otters near the urchin barrens than any other place in the vast sea.
Therefore,this is why urchin barrens are related to the presence big killer whales positively.
