QUESTION: Plankton diet
What do plankton eat?

        Christine M.
        Mrs. Garvin's Fifth Grade Science Class at Mauldin
        Elementary, Mauldin, SC Christine Marusich


ANSWER from Wendy Kozlowki, Researcher
            Palmer Station, Antarctica
            Fri, 21 Mar 1997 18:01:10 -0500



Dear Christine -

First of all, there are really three different groups of 
plankton in the oceans.  The first, with the smallest 
organisms, is called BACTERIOplankton.  The second is 
called PHYTOplankton, whose organisms fall into the 
plant kingdom, and the third is called ZOOplankton, 
and these are the "animals" of the plankton world.  
Bacterioplankton (similar to air-borne bacteria) and 
phytoplankton, like trees and plants that live above 
ground use the sun as their main source of energy - a 
"food" of sorts.  They also need certain nutrients in the 
seawater to live, and the Antarctic water masses are 
thought to have some of the most nutrient rich water 
in all the oceans.  No wonder the phytoplankton do so 
well here!  Zooplankton, the next step up in the food 
chain, feed on the phytoplankton.  Sometimes we catch 
krill (a type of zooplankton) that have "bellies" so full 
of phytoplankton they actually look green!  If you keep 
going up the food chain then, you get what are called the 
"apex predators" - whales and seals and birds and fish 
(to name a few) that feed on the zooplankton, as well as 
feeding on eachother!

Hope this answers your question -
Wendy Kozlowski