Dinoflagellates Dinoflagellates –Possess 2 flagella –Cell wall composed of response to sunlight –Bioluminescence –Harmful algal blooms

cellulose

–Autotrophic and heterotrophic abilities –Some ability to migrate vertically in

Coccolithophorids Calcium carbonate plates (

coccoliths

) cover the cell Blooms are visible from space As cells grow, coccoliths shed and sink to the bottom

Prasinophytes-a type of green algae Eukaryotes related to land plants Store starch and have chlorophyll The smallest known eukaryotic cell is

Ostreococcus

(Left) Another important small cell is

Micromonas

(right) Found in open ocean and near shore

Zooplankton

Two general categories of plankton

–Holoplankton

: spend their entire lives as plankton

–Meroplankton

: includes eggs, larvae, and juveniles of many species that are only plankton for a portion of their lives

The Holoplankton spend their entire lives as plankton

Zooplankton Herbivores, carnivores, or omnivores Some ability to swim, vertical migration Rapid growth rate and short lifespan  rapid liberation of nutrients Patchiness of population density

Most well studied and widespread groups are the crustaceans Copepods – Herbivorous – Link between photoplankton and first level carnovours Rapid swimming in a series of jumps

Euphausiids (Krill) – Omnivores – Occur in huge quantities near Antarctica where highest abundance of photoplankton are found. – Main food for Baleen whales – Up to 1.35 billion tons – Iodine content too high for human consumption – Harvested for animal feed.

Other important zooplankton include –Chaetognaths –Foraminifera and radiolarians –Tintinnids –Pteropods –Ctenophores –Salps –Cnidarians

Chaetognaths (Arrow worms) Voracious planktonic predators First level carnivores Abundant from surface to great depths Species are specific to water masses –Sagitta setosa: North Sea water –Sagitta elegans: Only in Oceanic waters

Foraminiferans, Radiolarians, Tintinnids Microscopic single celled amoeba-like protozoans Feed on phytoplankton and some zooplankton Forams encased in a calcareous covering Radiolarians encased in a silica test or shell Both found in warmer waters Upon death, shells settle to the bottom Forams in shallow water (Foraminiferan ooze) Radiolarians in deeper water (Radiolarian ooze) below 13,200 feet. Silica resists dissolving action Tintinnids: found in coastal waters

Ctenophores Comb jellies, sea walnuts, sea gooseberries Transparent, gelatinous, bioluminescent Float in surface waters All are carnivores

Pteropods Mollusks Holoplanktonic Related to snails Some are carnivores, others are herbivores Upon death, shells settle to the bottom and form Pteropod Oozes.

Salps Pelagic tunicates-related to chordates A group of underwater saclike filter feeders Feed on phytoplankton Live in a gelatinous walnut size house