euphausiid
noun
eu·phau·si·id yü-ˈfȯ-zē-əd 
: any of an order (Euphausiacea) of small usually luminescent malacostracan crustaceans that resemble shrimp and in some areas form an important element in marine plankton
euphausiid adjective
Example Sentences
Recent Examples on the Web Although their biological samples were low overall, scientists did find creatures, including small crustaceans called copapods, as well as euphausiids, or krill, a shrimp-like crustacean. 
San Diego Union-Tribune, 5 Aug. 2019
San Diego Union-Tribune, 5 Aug. 2019 Word History
Etymology
New Latin Euphasia, a genus of krill (from eu- eu- + Greek phaúsis "lighting, illumination" —from phau-, base of pháe "[it] shines" + -sis -sis— + New Latin -ia -ia entry 1) + -id entry 1 — more at photo-
Note: The genus name Euphausia was introduced by the American geologist and zoologist James Dwight Dana (1813-95) in "Synopsis Generum Crustaceorum Ordinis 'Schizopoda'," The American Journal of Science and Art, 2nd series, vol. 9 (May, 1850), pp. 129-33.
First Known Use
1885, in the meaning defined above