One possible reason could be the ability to avoid predation by protists.

When the amount of moonlight is great they retreat underground in order to avoid predation.

Preventive measures to avoid predation were also lacking in both cases.

Other situations can also be found where bird colonies avoid predation.

In general, the other species will leave the carcasses for the bear to avoid competition or predation.

Also, to avoid predation, many species are dark to blend in with their environment.

Organisms started burrowing to avoid predation at around the same time.

This is one way insects avoid predation during their most vulnerable life stage.

The best chance for an adult razorbill to avoid predation is by diving.

To be watery and transparent is a successful way to avoid predation.