What microscopic animal feeds on phytoplankton?

There are many microscopic animals that feed on phytoplankton, collectively called zooplankton. Some examples include:

* Copepods: Tiny crustaceans that are a major food source for many larger animals.

* Rotifers: Small, wheel-shaped animals with cilia that help them move and capture food.

* Cladocerans: Small, crustaceans with a carapace (shell) that covers their body.

* Foraminifera: Single-celled organisms with a shell made of calcium carbonate.

* Radiolarians: Single-celled organisms with a skeleton made of silica.

These are just a few examples, and there are many other types of zooplankton that feed on phytoplankton. The specific type of zooplankton that dominates a particular ecosystem will depend on factors such as water temperature, salinity, and nutrient availability.