2. Diatom Thalassiosira pseudonana 1.Eukaryote 2.Nuclei in Cells 3.Single Celled 4.No cell wall 5.Autotroph 6.Sessile (but planktonic– floats in the current of the ocean) 7.Asexual reproduction 8.Kingdom Protista

3. Diatom Thalassiosira pseudonana Diatoms live in the ocean as free-floating phytoplankton “phyto” because they are autotrophs and use light to produce food. “plankton” because they are moved around in the ocean by the current– unable to swim against it.

4. Base of Marine Food Web There are many species of single-celled algae that make up the base of ocean food web. These phytoplankton are eaten by “zooplankton” like tiny shrimp and these zooplankton are eaten by larger species like fishes, anemones, and even whales.

5. Oxygen Production Not only do these microscopic algae act as the base of a huge food chain, they also produce huge amounts of oxygen for us and other heterotrophs to breathe. 20-25% of all the oxygen available in the air and water is produced by these small autotrophs. We couldn’t survive without them!

6. Related to Seaweed These single-celled creatures are related to simple multicellular autotrophs like seaweed and kelp. Seaweed are not plants (they don’t have cell walls, roots, and other complex structures) but are actually simple multicellular protista.

7. Seaweed Uses Seaweed has many uses for humans as fertilizer, fuel, and food. Seaweeds also provide vital habitat for many ocean creatures including urchins and sea otters.