Zoology 200 Chapter 3 Dr. Bob Moeng Autotrophs Primary Producers Diversity of Organisms • Range of organisms categorized by taxonomic classification • Taxonomic relationships suggest evolutionary (phylogenetic) relationship • Five Kingdoms – Monera - procaryotes, bacteria and cyanobacteria • Single celled • Lack nucleus, multiple chromosomes, chloroplasts and mitochondria • Bacteria are decomposers • Cyanobacteria are photosynthetic and important phytoplankton – Protista - single-celled or aggregated eucaryotes, • Other major phytoplankton • Also include protozoans – Fungi • Few species by comparison • Also serve as decomposers – Plantae • Multicellular • Photosynthetic • Cellulose cell walls • Alternating gametophyte and sporophyte generations – Animalia • Multicellular • Non-photosynthetic • No cell walls Other Levels of Classification • Phylum/Division • Class • Order • Family • Genus • Species - a population of similar individuals that can or normally do interbreed and produce fertile offspring Primary Producers • Largely photosynthetic – Conversion of light energy into chemical energy – Need light, CO2 and photosynthetic pigment – Produces O2 and glucose – Pigments include chlorophylls, xanthophylls (particularly fucoxanthin), carotenes and phycobilins 3-1 Zoology 200 Chapter 3 Dr. Bob Moeng • Several important roles – Capturing energy and making it available for living organisms – Manufacturing O2 – Recycling of carbon through production of CO2 • Include three kingdoms – Monera - Division Cyanobacteria – Protista - Divisions Chrysophyta, Dinophyta – Plantae – Divisions Clorophyta, Phaeophyta, Rhodophyta, Anthophyta Planktonic Producers • Monera and Protista – Single-celled • Range of sizes - some are so small they are difficult to collect in numbers – Picoplankton - <2 µm (10-6) – Ultraplankton - 2-5 µm – Nanoplankton - 5 -20 µm – Microplankton - 20-200 µm • Most important are nanoplankton or smaller Cyanobacteria • Also call blue-green algae • Most less than 5 µm • Procaryotic with few membrane bound organelles • Abundant in intertidal and estuarine • Typically benthic • In some, population blooms – Oscillatoria causes red for Red Sea • May aggregate to form strands or dense mats – Long strands of Lyngbya • Reproduce by cell fission (usually) • Some are nitrogen fixators (like legumes) – Utilized gaseous N3 • Some symbiotic relationships with other marine organisms, even diatoms – Nitrogen fixing species with turtle grass (as an epiphyte) providing nutrient source Chrysophyta • Two major classes - Chrysophyceae, Bacillariopyceae • Photopigments include chlorophyll a, c and xanthophyll • Usually have hardened structural support (out or in) of silica or calcium carbonate which ultimately become part of sediments • Some have flagella for limited motility 3-2 Zoology 200 Chapter 3 Dr. Bob Moeng • Two groups of Chrysophyceae found in marine environment – Coccolithophores • Numerous calcareous plates in cell wall • May play valued role in total photosynthesis, particularly in tropical regions • Reproduce by cell fission – Silicoflagellates • Internal siliceous deposit • One or two flagella • Reproduce by cell fission • Of the Bacillariophyceae, diatoms are most abundant – Unicellular, but may aggregate in strands or clusters – Typically 50-500 µm in size – Cell wall with pectin and silica (frustule) • Include two overlapping halves – Reproduce by cell division • Can reproduce rapidly (1 million daughter cells in 3 weeks) – Contain chloroplasts – Shape either radially symmetrical (centric diatoms) or bilateral (pennate diatoms) – Pennates can move by undulation of cytoplasmic surface (typically in sediments or attached to plants or animals) Dinophyta • Unicellular with large nucleus • 25 - 1000 µm • Typically with two flagella – One flagellum around transverse groove – One longitudinal flagellum pointing forward • Reproduce asexually by cell division – Produce water coloration due to blooms • Most photosynthetic with small chloroplasts • Certain genera (Noctiluca & Ceratium) are bioluminescent – Luciferin is oxidized by luciferase, releasing energy in the form of light • Some produce toxins that increase in concentration during blooms and are concentrated by successive trophic levels – Red tides and neurotoxic shellfish poisoning (Ptychodiscus) – Paralytic shellfish poisoning or saxitoxin (Alexandrium) – Ciguatera fish poisoning (Gambierdiscus) • A few have a significant symbiotic relationship with other organisms (zooxanthellae) including hermatypic corals (reef building corals), giant clams, anenomes and some flatworms Chlorophyta 3-3 Zoology 200 Chapter 3 Dr. Bob Moeng • Largely freshwater and brackish • Less than 20 µm in size Planktonic Adaptations • Predation - spines • Sinking (staying in the photic zone) - increased surface to volume ratio, asymmetrical shape, gas-filled vesicles • Seasonal light or nutrient limitations - more chloroplasts, use of stored molecules or absorb them from environment, formation of cysts (low metabolic demand) 3-4 .