Copepoda

noun plural

Co·​pep·​o·​da kō-ˈpep-ə-də 

: a class of Crustacea comprising minute aquatic forms abundant in both fresh and salt waters and including some (as of the order Calanoida) that are chiefly free-living and important as fish food and others (as of the order Siphostomatoida) that are parasitic on the skin and gills of fish

copepod

ˈkō-pə-ˌpäd 

noun or adjective