160 likes | 1.1k Vues
What are the Different Types of Animal-like Protists?. Protozoans (Kingdom Protista*): unicellular heterotrophs, classified by organelles of motility (* non-monophyletic)
E N D
What are the Different Types of Animal-like Protists? • Protozoans (Kingdom Protista*): unicellular heterotrophs, classified by organelles of motility (* non-monophyletic) • Zooflagellates (Subphylum Kinetoplasta) and Diplomonads: flagella; all animal-like taxa are parasitic, with stiffened cell membrane (pellicle); diplomonads lack mitochondria • Dinoflagellates (Phylum Dinoflagellata): bodies naked or encased in cellulose plates, typically bear two flagella, with grooves in plates; bioluminescence (Noctiluca) and fish-killing forms (Pfiesteria) • Ciliates (Phylum Ciliophora): cilia; multinucleate, common aquatic primary consumers, with oral groove; sessile, free-living, and symbiotic forms; reproduce asexually (fission) or sexually (conjugation) • Sporozoans (Phylum Apicomplexa): non-motile endoparasites with apical complex (aids entry into host) • Amebas: pseudopods; shelled forms are important zooplankton: • Foraminiferans: calcareous tests, with net-like reticupodia for prey capture • Radiolarians: siliceous tests, with multiple, retractable actinopodia
What Diseases are Caused by Protozoans? • Caused by Sporozoans • Malaria: 700,000 – 2 million deaths/year (75% are children in Africa); caused by Plasmodium spp. (spread via mosquito bites); dormant liver stage (merozoites) followed by destruction of red blood cells by trophozoites( high fever) • Toxoplasmosis: parasite of cats, widespread in humans, affects pregnant women and those with compromised immune systems (HIV sufferers) • Caused by Zooflagellates, Diplomonads, Dinoflagellates • African Sleeping Sickness: caused by Trypanosomabrucei, spread via tsetse fly (~10,000 cases/year) • Chagas’ Disease: caused by Trypanosomacruziin Central and South America, spread by kissing bugs (~45,000 deaths/year) • Giardia: caused by Giardia lamblia(Diplomonad), causes severe diarrhea, spread via animal feces in streams and lakes (hikers contract) • Paralytic Shellfish Poisoning and Ciguatera: caused by dinoflagellate toxins (ex. domoic acid); risks involve red tides, eating tropical piscivores (ex. barracuda) • Others: amebic dysentery and meningitis, trichomonas(STD)