A sea slug which eats stinging Hydroids. In its mouth it has a gland which paralyzes the stinging cells which are subsequently stored in protrusions on its back. When attacked, the sea slug expels the stinging cells, so it defends itself with the weapons of its devoured victims (California).

 

A ghost pipe fish hides amongst the arms of a feather star (Philippines).

 

Most sharks have to swim all the time in order to keep a flow of oxygen rich water through their gills. However, where there are currents, sharks may lie motionless with their mouths open as in the case in this cave system in an island off the coast of Egypt (Red Sea).