Plankton (General)
Plankton are organisms that drift with the ocean currents. They come in a wide variety of shapes and colors. Their sizes can range from microscopic plants to jellies that are over 120m (393ft) in length! Some plankton are plants (phytoplankton) and others are animals (zooplankton). Both serve important roles in supporting larger food webs in the ocean. Some animals spend part of their lives as plankton while others drift in the ocean currents their whole lives like sea jellies!
Originally published: July 22, 2024
Last updated: March 20, 2026
SPECIES IN DETAIL
Plankton (General)
CONSERVATION STATUS: Not evaluated
CLIMATE CHANGE: Laboratory Evidence
Geographic Distribution
Plankton are found worldwide.
Habitat
Plankton are found in open waters and along the coastline.
Physical Characteristics
Plankton are extremely diverse, so what they look like depends on the species. Many have flat or slightly transparent bodies which allow them to float in the ocean currents and camouflage from predators.
Size
The smallest plankton is a type of microscopic cyanobacteria Prochlorococcus which measures less than a centimeter long (0.6 micrometers). The biggest plankton is the lion’s mane jelly which can be up to 120 meters (400 feet) long.
Diet
This is species dependent. Phytoplankton are producers, getting their energy from sunlight through photosynthesis. Zooplankton are consumers and must hunt for their food. Depending on the species, zooplankton may eat phytoplankton, other smaller zooplankton or even small fish!
Reproduction
This is species dependent. Phytoplankton typically reproduces asexually by splitting rapidly or fragmentation. A plankton bloom can happen when they reproduce rapidly in ideal conditions.
Some zooplankton reproduce asexually through budding or making copies of themselves (in one phase of sea jelly reproduction). Some release eggs and sperm into the water column to combine. Others may brood eggs on their bodies before they hatch.
Behavior
Plankton are drifters. They move with the ocean currents and cannot swim against them.
Adaptation
Plankton have different methods of helping them keep afloat in the ocean. Their flat bodies or presence of spines can increase their surface area and decrease drag. This allows them to stay afloat longer.
Longevity
This is species dependent.
Conservation
Plankton are important due to their role as the base of the food web. Phytoplankton are food for many zooplankton which in turn are the prey of smaller invertebrates, fish, and even whales. Phytoplankton produces roughly 50% of the world’s oxygen. Phytoplankton also acts as a carbon sink, absorbing carbon dioxide from the atmosphere into their bodies, which helps to mitigate the effects of climate change. Conservation efforts with plankton focus on monitoring their habitats instead of a particular species of plankton. By protecting their habitats, we can help preserve the balance of food webs that depend on them.
Special Notes
The word plankton comes from the Greek word planktos, which means “drifter” or “wanderer”.
Different animals may spend all or part of their lives as plankton. Animals that are meroplankton spend part of their life as plankton. Many crabs, sea stars, and even fish start out in a planktonic stage before settling into their adult form. Holoplankton spend their whole life as plankton. These would include animals like sea jellies, krill, and copepods.
SPECIES IN DETAIL | Print full entry
Plankton (General)
CONSERVATION STATUS: Not evaluated
CLIMATE CHANGE: Laboratory Evidence
Plankton are found worldwide.
Plankton are found in open waters and along the coastline.
Plankton are extremely diverse, so what they look like depends on the species. Many have flat or slightly transparent bodies which allow them to float in the ocean currents and camouflage from predators.
The smallest plankton is a type of microscopic cyanobacteria Prochlorococcus which measures less than a centimeter long (0.6 micrometers). The biggest plankton is the lion’s mane jelly which can be up to 120 meters (400 feet) long.
This is species dependent. Phytoplankton are producers, getting their energy from sunlight through photosynthesis. Zooplankton are consumers and must hunt for their food. Depending on the species, zooplankton may eat phytoplankton, other smaller zooplankton or even small fish!
This is species dependent. Phytoplankton typically reproduces asexually by splitting rapidly or fragmentation. A plankton bloom can happen when they reproduce rapidly in ideal conditions.
Some zooplankton reproduce asexually through budding or making copies of themselves (in one phase of sea jelly reproduction). Some release eggs and sperm into the water column to combine. Others may brood eggs on their bodies before they hatch.
Plankton are drifters. They move with the ocean currents and cannot swim against them.
Plankton have different methods of helping them keep afloat in the ocean. Their flat bodies or presence of spines can increase their surface area and decrease drag. This allows them to stay afloat longer.
This is species dependent.
Plankton are important due to their role as the base of the food web. Phytoplankton are food for many zooplankton which in turn are the prey of smaller invertebrates, fish, and even whales. Phytoplankton produces roughly 50% of the world’s oxygen. Phytoplankton also acts as a carbon sink, absorbing carbon dioxide from the atmosphere into their bodies, which helps to mitigate the effects of climate change. Conservation efforts with plankton focus on monitoring their habitats instead of a particular species of plankton. By protecting their habitats, we can help preserve the balance of food webs that depend on them.
The word plankton comes from the Greek word planktos, which means “drifter” or “wanderer”.
Different animals may spend all or part of their lives as plankton. Animals that are meroplankton spend part of their life as plankton. Many crabs, sea stars, and even fish start out in a planktonic stage before settling into their adult form. Holoplankton spend their whole life as plankton. These would include animals like sea jellies, krill, and copepods.