No Slide Titlebfleury/diversity/protista.… · PPT file · Web view · 2013-09-17Kingdom...
Transcript of No Slide Titlebfleury/diversity/protista.… · PPT file · Web view · 2013-09-17Kingdom...
Kingdom Protista
Kingdom Protista
• Kingdom Protista - 65,000-200,000 species (est.), fr. Greek protos = first, ktistos = established - algae, protozoans
• Also called Kingdom Protoctista
• Taxonomic “grab bag”, primitive organisms only distantly related (polyphyletic)
Kingdom Protista
• All protists are eukaryotes
• All protists are aquatic
• Unicellular or multicellular
• Some are colonial - cells specialize in different function (feeding, reproduction) = division of labor, communication
Kingdom Protista
• Some are autotrophs = algae
• Some are heterotrophs = protozoa
• Reproduce either sexually or asexually (by binary fission)
• Complex life cycles
Kingdom Protista
• Protists are so small they don’t need special organs to exchange gas or excrete wastes
• They rely on diffusion - passive movement of molecules from area of higher concentration to area of lower concentration
• Diffusion results from the random movement of molecules
Kingdom Protista
• Diffusion is a two edged sword
• Protists don’t need to invest in complex respiratory or excretory tissue
• They have to stay tiny - diffusion only works if you’re very small
• Most protists are single cells
Kingdom Protista
• Size is also limited by means of locomotion
• Many protists are propelled by cilia or flagella, tiny movable hairs
• Protists eat by phagocytosis> Engulf food in cell membrane
> Pinch off membrane to form a vacuole
> Vacuoles store food, water, enzymes, wastes
Phagocytosis
Didinium devours Paramecium
Kingdom Protista
• All of these traits are primitive - similarities may be due to convergent evolution
• Protists are mainly defined by what they are not> Not bacteria, archaea, or fungi…
> Not plants or animals…
Kingdom Protista
• Protists gave rise to all other plants and animals
• Phylogeny of protists still a real mess
• We assume they rose from certain groups of archaeans, but which?
Kingdom Protista
• Protists are so different from one another, most may represent several early independent lineages of eukaryotes
• First evolved ~ 1.2 billion years ago
• As many as 50 phlya recognized
• We’ll focus on several typical phyla
Kingdom Protista
• Protozoa - heterotrophs > Motile
– Cilia – Ciliophora
– Flagella – Dinoflagellata, Euglenozoa
– Pseudopodia – Amoebozoa, Foraminifera
> Non- motile - Apicomplexa
• Gave rise to higher animals
Kingdom ProtistaPhylum Euglenozoa
• 800 sp. - Euglena
• Plant or animal? Heterotrophs, but 1/3d are also photosynthetic
• May have formed by endosymbiosis, engulfed green algae cell
Euglena
Euglena
Kingdom ProtistaPhylum Dinoflagellata
• Dinoflagellates - 3,000 species, fr. Greek dinos = whirling, Latin flagellum = whip - Ceratium, Gonyaulax
• About half are photosynthetic
Dinoflagellates
Kingdom ProtistaPhylum Dinoflagellata
• Two flagella, one like a belt, one like a tail
• Many have armor of cellulose plates encrusted with silica
Dinoflagellates
Kingdom Protista Phylum Dinoflagellata
• Importance
> Zooxanthellae, dinoflagellates that have lost flagella & armor, live as symbionts in mollusks, sea anemones, jellyfish, coral
> Make coral more productive, limits coral to shallow water
Kingdom Protista Phylum Dinoflagellata
• Importance
> Algal blooms of dinoflagellates are the cause of red tide - 20 species produce potent toxins
> 1987 outbreak killed half the Western Atlantic population of bottlenose dolphin!
> Could make La. oysters an unforgettable experience…
Red Tide 2010 Breton-Chandeleur
Kingdom ProtistaPhylum Apicomplexa
• Apicomplexa are spore-forming parasites
• One end has an apical complex, apparatus designed to let them invade a host cell
• Sometimes called sporozoans, many form non-motile spores
Kingdom ProtistaPhylum Apicomplexa
• Plasmodium – causes malaria
• Spores are passed from one host to the next by vectors (mosquitoes etc.)
• Typical parasite life cycle, with intermediate hosts
Kingdom ProtistaPhylum Ciliophora
• 8,000 species, fr. Latin cilium = eyelash, Greek phorein = to bear - Paramecium, Blepharisma
• Complex little critters - many organelles and specialized structures
Blepharisma
Kingdom Protista
• Paramecium (and many other protists) have a contractile vacuole
• Complex vacuole that drains wastes from the cell
Contractile Vacuole of Paramecium
Kingdom ProtistaPhylum Ciliophora
• Move by numerous cilia
• Many ciliophorans defend themselves by discharging little toxic threads or darts
Paramecium, with cilia stained
Kingdom ProtistaPhylum Ameobozoa
• Over 300 species – true amoeba
• Move by pseudopods - extend part of cell to form a “false foot”, then flow into it (cytoplasmic streaming)
• Eat other protozoans, algae, even tiny multicellular creatures
Amoeba
Kingdom Protista Phylum Ameobozoa
• Many amoeba are parasites> Entamoeba histolyca - amoebic dysentery,
infects ~10 million Americans, 50% of population in the tropics
Kingdom Protista Phylum Ameobozoa
• Many amoeba are parasites> Primary Ameobic Meningoencephalitis (PAM)
Naegleria fowleri enters the nostrils (frequently during swimming), attacks the brain, can be fatal within one week of symptoms
> PAM is relatively rare -120 U.S. cases in 25 years
Kingdom Protista Phylum Ameobozoa
• PAM cases include two people in La. in 2011 who died from nasal irrigation with infected water (has to go way up the nose)
• PAM killed a 4 year old child in LA in 2013 who got it from playing on a Slip ‘n Slide
• Later found in the municipal water supply in Arabi and Violet (a first) – easily killed by chlorination
Kingdom Protista Phylum Foraminifera
• Foraminifera> Marine forms, sculpted shells (calcium
carbonate)
> Extend cytoplasmic podia out along the spines
> Spines function in feeding, swimming
Kingdom Protista Phylum Foraminifera
• Importance> So abundant, they formed most of the world’s
limestone, marble, and chalk
> Great Pyramids composed of billions upon billions of foraminiferan shells
> Abundant in fossil record, used by geologists to help identify layers of rock - indicator species
Foraminiferan shells
Great Pyramids of Egypt
Kingdom Protista
• Algae – autotrophic protists> Photosynthetic
> Many referred to as “seaweeds”
> Gave rise to higher plants
• Phaeophyta, Bacillariophyta, Rhodophyta, Chlorophyta
Brown Algae - Fucus - rockweed
Kingdom ProtistaPhylum Phaeophyta
• Brown algae - 1,500 species, fr. Greek phaios = brown - Fucus, Sargassum, kelp
• Mostly marine
Kelp
Kingdom ProtistaPhylum Phaeophyta
• Largest protists, kelp up to 100 meters long
• Blades lack conducting tissue, rely on diffusion - can be large but must be thin
Brown Algae - Kelp
Brown Algae - Saccorhiza polyschides
Kingdom ProtistaPhylum Phaeophyta
• Importance> Kelp forms the basis for major ecosystem along
the Pacific Coast and in other cool waters
> Sargassum forms large floating mats in the Atlantic, northeast of the Caribbean, a major ecosystem - Sargasso Sea once thought to trap ships
Kelp
Kingdom ProtistaPhylum Baccilariophyta
• Diatoms - 11,500 species
• Golden-brown pigment
Kingdom ProtistaPhylum Baccilariophyta
• Abundant in freshwater and marine habitats
• Shells made of organic compounds impregnated with silica (CD jewel case)
Kingdom Protista Phylum Baccilariophyta
• Importance> So abundant they account for a large percentage
of the oxygen added to the atmosphere
> Shells form deposits called diatomaceous earth, used in abrasives, talc, and chalks
> Lompoc CA quarry - 270,000 metric tons/year, Santa Monica bed is over 900 meters thick!
Kingdom ProtistaPhylum Rhodophyta
• Red algae - 4,000 species, fr. Greek rhodos = red - Polysiphonia, Nemalion
• Mostly marine, closely related to green algae
• Red algae dominate in salt water, green algae dominate in fresh water
• Elaborate life cycles
Kingdom ProtistaPhylum Rhodophyta
• Red algae plastids (rhodoplasts) similar to certain cyanobacteria, acquired through endosymbiosis
• Brown algae formed in similar fashion, eukaryotic protist swallowed a red algae
Red Algae - Scinaia furcellata
Kingdom ProtistaPhylum Rhodophyta
• Importance> Agar from cell walls used for culture plates
> Carrageen, thickening agent also extracted from red algae, used in making ice cream, lunch meats, cosmetics, paint, beer and wine!
Kingdom ProtistaPhylum Chlorophyta
• Green algae - ancestral to land plants
• Recently recognized as sister taxon to land plants
• Now “bumped up” to Kingdom Viridiplantae (algae + land plants)
Chlorophyta