Some zooplankton belong to the kingdom Protista. Members of this kingdom are characterized as

Zooplanktons belong to protista kingdom.

Explanation:

Protists are Eukaryotas. They have a nucleus and other organelles. But, most of the protists are singe celled. Most protists are so small, that they can only be seen under the microscope. Some protists may be multi cellular also (example-kelp). Most of the protists have mitochondria. They generally prefer aquatic or moist environment. They can be parasites.