Chapter 26 Animal Diversity I Protists 26 1 Diversity in The Protists Protists are a source of food oxygen in aquatic environments economically important and cause diseases most protists are unicellular some are multicellular some protists form colonies loosely connected groups of cells Coenocytic consisting of a multinucleate mass of cytoplasm some protists are coenocytic Protists Locomotion motile at some point in their life move through different ways pushing out cytoplasmic extensions pseudopodia by flexing individual cells by gliding over surfaces by waving cilia short hairlike organelles or by lashing their flagella whip like organelle Some protists can move by more than one ex flagella pseudopodia Protists Obtaining nutrients most algae are autotrophic photosynthesize heterotrophic protists obtain nutrients through absorption Others ingest food Mutualism more or less equal partnership where both partners benefit commensalism where one partner benefits and the other is unaffected parasitism where one partner the parasite lives on or in another the host and metabolically depends on it some protists are pathogens disease causing agents most live in the ocean or freshwater make up most of the plankton protists reproduce sexually asexually 26 2 How Did Eukaryotes Evolve Eukaryotes may have appeared as early as 2 2 billion years ago serial endosymbiosis one organisms engulfed another certain eukaryotic organelles like mito chondria chloroplasts arose from symbiotic relationships mitochondria originated from aerobic bacteria chloroplasts come from cyanobacteria primary endosymbiosis where a cyanobacteria was engulfed Ultrastructure is the fine details of cell structure revealed by electron microscopy electron microscopy reveals similar structure patterns that are monophyletic monophyletic evolved form a common ancestor biologists regard protists as a paraphyletic group that contain some but not all of the descendants of a common eukaryote ancestor 26 3 Excavates Excavates a diverse group of unicellular protists with flagella deep excavated oral groove live in anoxic w o oxygen environments not carry out aerobic respiration obtain energy through glycolysis include diplomonads parabasalids euglenoids and trypanosomes Types of Excavates diplonomads one or two nuclei no functional mitochondria no golgi complex up to 8 flagella Ex Giardia is a parasitic diplomonad causes water borne diarrhea parabasilids anaerobic flagellated live in animals often ex triconymphs try panosomes Ex Trichonymphs hundreds of flagella live in the guts of termites and wood eat ing cockaroaches Trichomonad causes trichomoniasis an STD They ingest the wood chips the bacteria digest the cellulose in the wood both insects and tricho nymphs obtain nutrients from this source Euglenoids 9 2 arrangement of microtubules unicellular about 1 3 photosynthetic two flagella move by pellicle heterotrophic by ingesting organic matter or phagocytosis autotrophic ex Euglena Trypanosomes single mitochondrion has kinetoplastid organized deposit of DNA many parasitic cause disease some are colorless live in the blood Trypanosoma brucci causes African sleeping sickness 26 4 Chromalveolates Chromalveolates originated most likely as a result of secondary endosymbiosis ancestral cell engulfed a red alga mostly photosynthetic some heterotrophic divided into two major groups alveolates stramenopiles Types of Chromalveolates Alveolates dinoflagellates apicomplexans ciliates Dinoflagellates unicellular colonial aveoli contain cellulose plates with silicates 2 flagella bioluminescent photosynthetic heterotrophic live in the bodies or marine verte brates like mollusks jellyfish and corals called zooxanthellae help in the production of coral reefs parasites responsible for red tides Apicomplexans parasitic spore forming move by flexing have an apical complex of microtubules to attach to host produce sporozoites small infective agents transmitted to hosts cause malaria Ciliates unicellular pellicle have cilia two different nuclei micronuclei macronu cleus Micronuclei diploid and function in reproduction and macronucleus polyploid controls cell metabolism and growth capable of conjugation two individuals come to gether and exchange genetic material divide perpendicularly after conjugation Stramenopiles water molds diatoms golden algae brown algae Water molds have a mycelium threadlike hyphae make up the mycelium and are coenocytic consists of single multinucleate cell cell walls are composed of cellulose chitin or both reproduce asexually sexually form a structure called a zoosporgangium during sexually reproduction form oospores develop from oospheres female gametes Ex Phytophthora infestans caused Irish potato famine P ramorum which causes sudden oak death Diatoms unicellular some are colonies cell wall consists of two shells where silica is deposited have two groups those with radial symmetry those with bilateral symmetry some part of plankton live on rocks and sediments move by gliding secrete slimy mate rial to move reproduce asexually by mitosis sexual reproduction occurs when shell reaches fraction of its original size in fresh water cool ocean water when they die their shells accumulate and become sedimentary rocks used to refine raw sugar Brown Algae seaweed multicellular largest brown algae are called kelps both asexual and sexual have alternation of generation cell walls contain polysaccharide called algin help make toothpaste common in cooler marine waters Golden Algae found in freshwater and marine environments biflagellate unicellular colonial contain chloroplasts asexual reproduction results in zoospores photosynthetic make a significant portion of nano plankton 26 5 Rhizarians Rhizarians have hard outer shells called tests forams actinopods Foraminiferans marine rhizarians have tests have cytoplasmic projections that cap ture prey dead forams settle at the bottom of the ocean White Cliffs of Dover used as index fossils Actinopods have axopods that capture prey mostly marine plankton rhizarians ex radiolarians secrete glassy shells made of silica become an ooze at death 26 6 Archaeplastids Archaeplastids red algae green algae Red algae multicellular live in warm tropical waters ex coralline algae incorporate calcium carbonate in their cell walls help build coral reefs cell walls contain polysac charides like agar Green algae photosynthetic cellulose in walls asexual sexual reproduction pro duce zoospores asexually sexual