Figure 15 13 Dinoflagellates Dinoflagellates such as Gonyaulax have cellulose plates cellulose plate flagella Dinoflagellates supergroup Chromalveolata are photosynthetic but they have two flagella one is free but the other is located in a transverse groove that encircles the animal The beating of these flagella causes the organism to spin like a top The cell wall when present is frequently divided into closely joined polygo nal plates of cellulose At times there are so many of these organisms in the ocean that they cause a condition called red tide The toxins given off in these red tides cause widespread fish kills and can cause paralysis in humans who eat shellfishes that have fed on the dinoflagellates Heterotrophic Protists The term protozoan refers to single celled eukaryotes and its use is often restricted to heterotrophic orgar isms that ingest food by forming food vacuoles Other vacuoles such as contractile vacuoles that rid the cell of excess water are also typical Usually protozoans have some form of locomotion and as shown in Figure 15 14 some use pseudopodia some move by cilia and some use flagella Plasmodium vivax which causes a common form of malaria is an apicomplexan Apicomplexans have special organelles one is an apicomplast at the base of their flagella and the other contains organic chemicals that assist in penetrating host tissues Plasmodium spends a portion of its life cycle in mosquitoes sexual phase and the other part in human hosts asexual phase During the asexual phase of their life cycle all apicomplexans exist as particulate spores which accounts for why they are also called sporozoans In general how do sporozoans differ from the other protozoans shown in Figure 15 14 Plasmodium spores are the cause of malaria they multiply in and rupture red blood cells