mesoplankton

[ mez-uh-plangk-tuh n, mes-, mee-zuh-, -suh- ]
/ ˌmɛz əˈplæŋk tən, ˌmɛs-, ˌmi zə-, -sə- /

noun

plankton that live at middle depths.
planktonic organisms between 0.04 and 0.4 inches (1 mm and 1 cm) in length.

Origin of mesoplankton

First recorded in 1895–1900; meso- + plankton
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019