Transcript Plant-like Protists

Plant-like Protists
Plant-like Protists
• All are autotrophic.
• Sometimes referred to as algae even
though not all are algae
7 different phylums that we will look at
Euglenophyta
• Many are photosynthetic or producers
• Have a long flagellum at one end of the
cell
• Contain a special vacuole called a
contractile vacuole
• Have protein bands beneath the plasma
membrane that provide strength and
flexibility called a pellicle
Euglenophyta
• Have a specialized organelle called an
“eye spot” and a light detector.
• Allows Euglenids to exhibit phototaxis
• Example: Euglena
Dinoflagellata
•
•
•
abundant components of both marine
and freshwater phytoplankton (base of
food chain). There are some
heterotrophic dinoflagellates.
Most are unicellular, some are colonial.
Cell wall composed of cellulose
Pfiesteria piscicida
Dinoflagellata
• Bioluminescent – ATP-driven chemical
rxn. That creates an eerie glow at night
when waves, boats, or swimmers agitate
seawater with dense populations of the
dinoflagellates. May attract fishes that eat
predators of the dinoflagellates
Dinoflagellates
Dinoflagellata
• Red Tides: explosive population growth,
“bloom” of dinoflagellates, appear
brownish-red. Toxins produced by
dinoflagellates can cause massive kills of
invertebrates and fishes. Eating molluscs
that have accumulated the toxin can affect
humans
Red Tide
Chrysophyta: “Golden Algae”
•
•
•
Named for their color, result from their
yellow and brown carotenoids
Cells are biflagellated, flagella attached
near one end of the cell
Part of freshwater and marine plankton
Chrysophyta
• All are photosynthetic (producers).
• Some are mixotrohpic, can absorb
dissolved organic compounds or ingest
food particles and prokaryotes by
phagocytosis
• Most are unicellular, some colonial
• Source of food for other organisms
Bacillariophyta
•
•
•
•
Ex. Diatoms
Approx. 100,000 living species
Unicellular algae
Cell wall composed of a glass-like wall
made of hydrated silica. Consists of two
parts that overlap, provide protection.
Bacillariophyta
• Normally reproduce asexually by mitosis.
• Some species form cysts as resistant
stages.
• Major component of phytoplankton in the
ocean and lakes.
• Being studied for possible uses in
nanotechnology
Phaeophyta: “Brown Algae”
•
•
•
•
•
Largest and most complex algae
All are multicellular
Most are marine
Common along temperate coasts
Include many seaweeds, which have the
most complex multicellular anatomy of
all algae
Phaeophyta: Structure
• Thallus – a seaweed
body that is plant-like.
The thallus lacks true
roots, stems, and
leaves. The thallus is
composed of a
holdfast, stipe, and
blades
Phaeophyta: Structure
• Holdfast – rootlike structure which anchors
the alga
• Stipe – stem like structure which supports
the leaf-like blade
• Blade – provides most of the surface for
photosynthesis
• Cell wall composed of cellulose and gelforming polysaccharides (prevents drying
and cushions the thalli from waves)
Kelp
Chlorophyta: Green Algae
• Named for their green chloroplasts which
are similar to those of plants
• Closely related to land plants, probably
gave rise to land plants
• Divided into two main groups:
– Chlorophytes
– Charophyceans
Chlorophytes
• More than 7,000 species identified
• Most live in freshwater, but many are
marine
• Multicellular and colonial
• Alternation of Generations
Volvox
Rhodophyta: Red Algae
• Red because of an accessory pigment:
phycoerythrin, masks the green of
chloroplasts
• Most abundant large algae in warm
coastal waters of tropical oceans
• Pigments allow them to absorb blue and
green light
Rhodophyta: Red Algae
•
•
•
•
•
•
•
Live in deep water
Most are marine
All are multicellular
Alternation of Generations
Producers
Provide a source of oxygen
Used to make sushi