Greenwich Bay

Most plankton are microscopic, but not all. Plankton range in size from less than 0.005 millimeters (bacteria) to nearly 15 meters long. What plankton is 15 m long? Hint: Greenwich Bay is home to relatives of this animal. You may notice them during the summer. When you go swimming, you probably try to avoid them! For the answer, see below.

Zooplankton make up the animal component of the plankton community. With only a few exceptions, they are tiny creatures, many of whom are barely visible to the naked eye.

Some of the zooplankton in Greenwich Bay are planktonic their whole lives, and are called holoplankton.

Others are merely plankton for the first part of their lives, and these are called meroplankton. Can you guess some of the familiar animals that spend part of their lives as plankton?

Holoplankton: Cuckoo for Copepods

Half to three-fourths of the zooplankton in the bay are tiny crustaceans called copepods.

Copepods are major consumers of phytoplankton.

Meroplankton: The Start of Something Big

The eggs and larvae of nearly all fish and benthic (bottom-dwelling) animals are part of the plankton community. Many zooplankton (zoo = animal, plankton = drifter) are tiny, larval stages of familiar animals such as fish, clams, and crabs (see above). These part-time plankton are known as meroplankton. They begin as eggs, then move through one or more developmental (or larval) stages before they take their final adult forms. Often, the planktonic stages look completely different from the animals we know in their adult forms. Some common examples are:

A: One common member of the plankton community is surprisingly different from the others. Since plankton are defined as organisms that float and drift with winds and currents (many plankton are able to swim, but they are not strong enough to set their own course against the direction of these winds and currents), jellyfish and their familiar relatives, comb jellies, or ctenopohores, are also considered plankton.