Lecture Marine Heterotrophic Protists - KOCWcontents.kocw.net/KOCW/document/2016/chungnam/... ·...
Transcript of Lecture Marine Heterotrophic Protists - KOCWcontents.kocw.net/KOCW/document/2016/chungnam/... ·...
Lecture Marine Heterotrophic Protists
Protistan Groups
Ciliates
Sarcodines
Apicomplexans
Flagellates
Protistan Anatomy
Alveloates• The alveolates (meaning "with
cavities") - the presence of cortical alveoli, flattened vesicles packed into a continuous layer supporting the membrane, typically forming a flexible pellicle.
• In dinoflagellates they often form armor plates.
• Ciliates – very common protozoa with many short cilia arranged in rows, and two nuclei
• Dinoflagellates – mostly marine flagellates many of which have chloroplasts
• Some lack chlorophyll and are only heterotrophic, but are bioluminescent –Noctiluca = “night light”. Ingests particulate matter through phagocytosis.
• Some are parasitic on invertebrates, vertebrates and other protozoans.
Noctiluca
Dinoflagellates
Immobilising and eating metazooplankton.
Karlodinium armiger ganging up and munching on a polychaete larva (Berge et al. 2012)
Phylum Ciliophora • Ciliates, a large varied group of
protists, are named for their use of cilia to move and feed
• Multinucleate– Macronucleus – controls
metabolism, synthesis of organic molecules and development of the organism
– Micronucleus – function in sexual reproduction (conjugation) and give rise to the macronucleus after sexual reproduction.
Phylum Ciliophora • feeds on organisms via a
cytostome• Defensive and predatory
adaptations– Trichocysts – defensive– Toxocysts – toxic to
paralyze prey– Mucocysts
Tintinnids
• Bell animals• Planktonic ciliates• Common in open ocean• Ring of cilia surround
mouth (locomotion & catching food).
• Hard shell of protein.
Cytostome• A cytostome (from cyto-, cell and stome-, mouth) or
cell mouth is a part of a cell specialized for phagocytosis
• Food is directed into the cytostome, and sealed into vacuoles.
• ciliates and excavates have cytostomes.
• cytostome only constitutes the opening of the invagination at the surface of the cell. The rest of the invagination is classified as the cytopharynx
Ciliophoran Reproduction
Perkinsus olseni
Rhizaria• having no clear morphological distinctive
characters, but for the most part they are amoeboids with filose, reticulose, or microtubule-supported pseudopods.
– Cercozoa – Various amoebae and flagellates, usually with filose pseudopods and common in soil
– Foraminifera – Amoeboids with reticulose pseudopods, common as marine benthos
– Radiolaria – Amoeboids with axopods, common as marine plankton
Cercozoans and radiolarians - have threadlike pseudopodia
• A newly recognized clade, Cercozoa, contains species among the organisms called amoebas
• Amoebas were formerly defined as protists that move and feed by means of pseudopodia
• Cercozoans are distinguished from most other amoebas by their threadlike pseudopodia
Polystomella strigillata
Bolivina subaenariensis – planktonic foraminifera approximately 1mm long.
Foraminiferans• are named for
porous, generally multi-chambered shells, called tests
• Pseudopodia extend through the pores in the test
• Foram tests in marine sediments form an extensive fossil record
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20 µm
Facts about Forams
• Shell made of Calcium carbonate. Individuals secrete multi-chambered tests, generally made of calcium carbonate (CaCO3)
• Pseudopodia project out through holes in shell.
• Feed on diatoms & other protozoans.
• Secrete digestive juices onto their food to dissolve it!!!
• Waste expelled through body surface.
Radiolarians
http://micro.magnet.fsu.edu/micro/gallery/radiolarians/radiohead.jpg
- have tests fused into one delicate piece, usually made of silica- phagocytose microorganisms with their pseudopodia- pseudopodia, known as axopodia, radiate from the central body
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Lectures by Chris Romero200 µm
Axopodia
Kinetoplastids• A kinetoplast is a network
of circular DNA (called kDNA) inside a large mitochondrion that contains many copies of the mitochondrial genome.
• Bodo is a typical genus within kinetoplastida and including various common free-living species which feed on bacteria.
Choanoflagellatges• Flagellates
• Propelled by a flagella
• Whip like
• Colonial, live attached to bottom.
• Collar filters particles from the water.
• the closest living relatives of the animals.
Some marine protists
Rhynchomonas nasuta
Parvicorbicula sp.Plagioselmis prolonga
Bodo saliens
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Mesodinium rubrum5µm
5µm
Heterotrophic nanoflagellates (HNF)
Ciliates
Paradigm change of the ocean’s food web
(Sherr and Sherr 2009)
(Zobell 1946)
(Pomeroy 1974)
“Microbial loop” – by Azam et al. 1983-Transfer of organic carbon from dissolved fraction to higher trophic levels in food chain via bacteria, nanoflagellates, and ciliates
sloppy feeding
Marine Microbial Foodweb