Plankton - Drifters of the Sea

Plankton are likely the most numerous organisms on Earth.  Planktonic viruses number about 10-100 million per teaspoon of seawater, bacteria come in second at about 1/10 that number.  Scientists estimate that if all the viruses were lined up end to end the line would reach out somewhere between 60 and 100 million light years. New findings by scientists estimate that 1/2 the ocean's planktonic bacteria are photosynthetic using a unique pigment, proteorhodopsin and other deep sea bacteria are photosynthetic using the dim light from deep sea thermal vents.
The ones we can observe with a magnification of as low as 10X are more familiar to the general public.
                                                     
                                             General Plankton Information
Holoplankton:  Planktonic organisms that spend their entire lives as members of the plankton.
Meroplankton:  Planktonic only in some stage of life.

Holoplankton include: Viruses, Bacteria,  Diatoms, dinoflagellates, other single cell algae, most copepods, some amphipods, arrow worms, pterapods, larvaceans, salps, some jellyfish, some protozoans and others.

Diatoms

diatom

Dinoflagellate

Larvacean

Noctiluca

Pteropod

Copepod

Rotifer

Krill

Meroplankton include:  Larval stages of :  crabs, shrimp, lobster, hermit crabs, barnacles, sea stars, sea urchins, sea cucumbers, sand dollars, most mollusks, many species of fish, sea anemones, tunacates, sponges, worms, bryozoans, various arthropods, salps, siphonophores, etc....and some stages of jellyfish, as well as reproductive cells of seaweeds

Larval Barnacle



Larval Barnacle



Amphipod

Parasitic Copepods

Crab Larvae

Larval Annelid Worm

Larval Sea Squirt

Larval Snail

Larval Fish

Larval Sea Slug

Larval Bryozoan

Larval Shrimp

Lion's Mane Jellyfish

Phytoplankton:  Plankton that are primary producers; they produce their own food, carbohydrates, through the process of Photosynthesis:  

Six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygen .

Included are certain bacteria, diatoms, coccolithophores, other algae, some dinoflagellates. 

These phytoplankton produce about 1/2 of the Earth's oxygen supply and form the base of the food web in much of the ocean.  The CO2 enters the ocean via the atmosphere....which at present in increasing and causing ocean waters to become more acidic (see earlier blog).  Phytoplankton also require other nutrients which may be the limiting factors in phytoplankton abundance.

Zooplankton:  Animal members of the plankton; both holoplankton and meroplankton. 

Many are larval stages or animals that will leave the plankton as adults; sea stars, sea urchins, sea cucumbers, sea squirts, crabs, shrimps, snails, clams, mussels, worms, sea anemones, bryozoans, barnacles, sand dollars, many fishes, sponges, oysters, are all meroplankton. while copepods, arrow worms, salps, larvaceans, are among the holoplankton.

Jellyfish have both attached and planktonic life stages.

Puget Sound Plankton:   See previous blog on "The Fertile Fjord" to learn more about our local plankton.

Don't forget you can get the book online from SEA GRANT.

Plankton images: The Seattle Aquarium and Richard Bell