16.15 Chromalveolates represent the range ofprotist diversity Chromalveolates include– diatoms, unicellular algae with a glass cell wallcontaining silica,– dinoflagellates, unicellular autotrophs, heterotrophs,<strong>and</strong> mixotrophs that are common components of marineplankton,– brown algae, large, multicellular autotrophs,– water molds, unicellular heterotrophs,– ciliates, unicellular heterotrophs <strong>and</strong> mixotrophs that usecilia to move <strong>and</strong> feed, <strong>and</strong>– a group including parasites, such as Plasmodium, whichcauses malaria.16.16 CONNECTION: Can algae provide arenewable source of energy? Fossil fuels– are the organic remains of organisms that livedhundreds of millions of years ago <strong>and</strong>– primarily consist of– diatoms <strong>and</strong>– primitive plants.© 2012 Pearson Education, Inc.© 2012 Pearson Education, Inc.16.16 CONNECTION: Can algae provide arenewable source of energy?Figure 16.16 Lipid droplets in diatoms <strong>and</strong> other algae mayserve as a renewable source of energy. If unicellular algae could be grown on a large scale,this oil could be harvested <strong>and</strong> processed intobiodiesel. Numerous technical hurdles remain beforeindustrial-scale production of biofuel from algaebecomes a reality.© 2012 Pearson Education, Inc.16.17 Rhizarians include a variety of amoebas16.17 Rhizarians include a variety of amoebas The two largest groups of Rhizaria are among theorganisms referred to as amoebas. Amoebas move <strong>and</strong> feed by means ofpseudopodia, temporary extensions of the cell. Foraminiferans– are found in the oceans <strong>and</strong> in fresh water,– have porous shells, called tests, composed of calciumcarbonate, <strong>and</strong>– have pseudopodia that function in feeding <strong>and</strong>locomotion.© 2012 Pearson Education, Inc.© 2012 Pearson Education, Inc.18
Figure 16.17AFigure 16.17A_1Figure 16.17A_216.17 Rhizarians include a variety of amoebas Radiolarians– are mostly marine <strong>and</strong>– produce a mineralized internal skeleton made of silica.© 2012 Pearson Education, Inc.Figure 16.17B16.18 Some excavates have modified mitochondria Excavata has recently been proposed as a cladeon the basis of molecular <strong>and</strong> morphologicalsimilarities. The name refers to an “excavated” feeding groovepossessed by some members of the group. Excavates– have modified mitochondria that lack functional electrontransport chains <strong>and</strong>– use anaerobic pathways such as glycolysis to extractenergy.© 2012 Pearson Education, Inc.19
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