What is plankton?
Plankton is a collective term for all the tiny plants, animals and bacteria that live in the open water column. These animals generally have no or little swimming ability, and are at the mercy of the ocean’s currents. Plankton is generally divided into 3 different classes based on their size:
- phytoplankton – microscopic plants and bacteria
- zooplankton – microscopic animals
- macro zooplankton – larger fish eggs and larvae and pelagic invertebrates
Some types of plankton have special hairs called cilia that move the animal around in the water column.
Is plankton good for the environment?
All things in good measure! Plankton is a major natural food source for many of the oceans creatures, from whales that feed on krill, to corals that supplement their photosynthetic diet with animal larvae. However, when levels of nutrients are excessively high in the water, phytoplankton will bloom en masse, which depletes oxygen in the water column. This can cause problems for other marine life.
Is plankton dangerous?
The beautiful intricate structures of creatures like diatoms can be revealed when viewed under a microscope. However, many carry an arsenal of stinging spines and hooks to defend themselves from other predatory plankton. Occasionally, people will swim through swarms of these creatures and develop a red rash that is quite itchy. This is known as “sea lice”, a generic term that describes any planktonic creature that can cause a sting or minor skin irritation. Of course, we are going to cause much more harm to these small creatures than they could ever do!
How do scientists study plankton?
Plankton is collected using fine mesh nets, usually dropped over the side of a vessel. The samples are deposited into clear jars, and then transferred to smaller dishes to allow them to be studied under microscopes. The plankton sample is then usually divided into family level and, if possible, described to species level. Certain types of plankton can be used as biological indicators of water quality, making them very useful for scientists studying the ocean.