hyperthermophiles that live in extremely hot environments above 176 degrees Fahrenheit. There is even a strain that can reproduce above the boiling temperature of water. There is a strain called Picrophilus torridus that can grow at the remarkable pH of 0. There is speculation that, in extreme outer space environments, these microbes might be the only form of life that is possible. They reside in high enough concentrations in the ocean to affect the ecology of the ocean; however, as many of these are just being discovered, it is no known how they play a role. They may partly play a role in the nitrogen cycle of the ocean by virtue of being able to undergo nitrification.
PROTISTA Protista is a kingdom among the eukaryotes that has not yet been discussed in this course. This is a heterogeneous group that consists mostly of unicellular or simple multicellular forms. There are many different types of organisms in this kingdom, including algae, protozoa, molds, and slime. They will have both sexual and asexual reproduction and can be sessile (nonmotile) or can move via cilia, pseudopodia, or flagella. The different subdivisions include diatoms, brown algae, green algae, slime molds, amoebas, flagellates, ciliates, foraminiferans, radiolarians, heliozoans, and apicomplexans (sporozoans). Many ingest food rather than synthesize food as is seen in plants. The major classifications depend on their methods of locomotion. Figure 34 shows some of the different types of Protista:
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