Invertebrate Protozoa protists Foraminiferans, radiolarians , amoebas Porifera sponges Chaetognatha Arrow worms Fig. The marine environment b. Zooplankton are the animals of the plankton. They are, by definition, carried passively along in the ocean - they cannot swim against the currents . There is an amazing array of organisms present among the zooplankton.
Protists are single-celled organisms.
There are many multi-cellular organisms. Zooplankton typically grow fast , and this is very dependent on the food supply. Foraminifera and radiolarians iii. Holoplankton live their entire life cycle in the plankton. Meroplankton live only part of their lives as plankton.