zooplankton

definition: 
Plankton consisting of small animals and the immature stages of larger animals
sentence: 
Oil and gas was formed around 100 million years ago when tiny marine plants and animals called phytoplankton and zooplankton floated on the sea's surface. They typically eat insects and floating vegetable matter but their diet also includes zooplankton, aquatic insect larvae, and worms.
difficulty: 
medium
toefl frequency: 
1
toefl classification: