1. Microscopic oceanic living plants or animals that exist within the surface of a sea down to about 200 m (the epipelagic zone): In Jane's biology class, the teacher explained the characteristics of epiplankton and that they inhabited surface water down to about 100 fathoms.
2. Organisms living attached to larger pelagic organisms or to floating objects: It has been discussed that epiplankton have fastened themselves to bigger lifeforms which drift along in the water.