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 gel-forming 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