Transcript Protists
Protists O’Connor Protists • organisms, comprising those eukaryotes that cannot be classified in any of the other kingdoms as fungi, animals, or plants. • they are unicellular or • they are multicellular without highly specialized tissues. How do they “eat”? • Protists obtain nutrients & digest nutrients in a complex acquirement & assimilation system. • Most protists also feed on bacteria. • Protists acquire their food material through internal digestion. • They extend their cell wall & cell membrane around the food material to form a food vacuole via endocytosis. Protozoa • animal-like protists • mostly single-celled, motile protists that feed by phagocytosis, though there are numerous exceptions. • generally too small to be seen without magnification. • Some protists are heterotrophs • Some protists are autotrophs • Some get nutrients by decomposing organic matter Protozoa are grouped by method of locomotion into • Flagellates with long flagella e.g., Euglena Amoeboids • with transient pseudopodia e.g., Amoeba Ciliates • with multiple, short cilia e.g., aramecium Sporozoanon • mobile parasites; some can form spores e.g., Toxoplasma Algae, the plant-like protists • include many single-celled organisms that are also considered protozoa, such as Euglena • which many believe have acquired chloroplasts through secondary endosymbiosis • Others are non-motile, and some (called seaweeds) are truly multicellular • Chlorophytes- green algae, are related to higher plants – e.g., Ulva • Rhodophytes- red algae – e.g., Porphyra • Heterokontophytes- brown algae, diatoms, etc. – e.g., Macrocystis Molds • Slime molds, water molds & downy mildews are fungus like protists that decompose organic material to obtain nutrients. • Plasmodial and cellular slime molds change in appearance and behavior before producing reproductive structures Slime Mold Water Mold Downy Mildew