Kingdom Protista. General Characteristics. Most are single-celled All are eukaryotic All are heterotrophic Microscopic Come in all shapes, sizes and colours Some have cell walls, some are motile
Sarcodines: these are the amoebae, move and engulf their prey by producing pseudopodia, which are extensions of their cytoplasm.
Ciliates: move by cilia beating in a coordinated rhythm, they also help move food into the paramecium’s gullet, which leads to a food vacuole. A paramecium is a ciliate.
Sporozoans: these are parasites, they have spores at some point in their lifecycle, they contain a number of complex organelles at one end of their bodies to help them invade their victim. Plasmodium vivax causes one type of malaria in humans.
Algae are classified into six different phyla based on the type of chloroplasts and pigments they contain. The chloroplasts in different types of algae have different types of chlorophylls and other pigments. This suggests that chloroplast-containing cells evolved three times.
Three phyla are unicellular and three are multi-cellular
Other differences include the chemistry of their cell walls, the number and position of flagella (if any) and the form that food reserves take in their cells.
Brown Algae (Phaeophytes): nearly all multicellular, which are commonly called seaweeds. They have cell walls made of cellulose and alginic acid (similar to pectin, which is used to thicken jams and jellies). They have adaptations to live in rough environments such as holdfasts that anchor the algae to the rocky seashore. Their fronds are tough enough to withstand the pounding of the waves. They are what let Colombus know he was close to land! Found in cold water.
Red Algae (Rhodophytes): multicellular seaweed found in warmer seawater. More delicate and smaller than brown algae. Why are they red? Because they contain pigments that absorb green, violet and blue light and since these wavelengths penetrate the furthest in water, they are able to live at deeper depths.
Dinoflagellates (Pyrophytes): unicellular, photosynthetic and mostly marine. They have protective coats made of stiff cellulose plates. They all have two distinct flagellae. One lies in a long groove on the covering plate with only its far end free. The second is flat and ribbon like and lies in a groove that encircles the dinoflagellate. They are extremely numerous and form an important base for marine food chains. Form red tides which cause toxins to built up in shellfish that eat them.
Euglenoids (Euglenophytes): unicellular freshwater organisms with two flagellae, one usually much longer than the other. They contain chloroplasts but if there is no sunlight then they lose their chloroplasts and ingest and eat food.
Plasmodial Slime Moulds (Myxomycotes): visible to the naked eye as tiny slug like organisms that creep over damp, decaying plant material in forests and fields. This blob, called a plasmodium, contains many nuclei. Feed in a similar manner to amoebae. Spores form in improper living conditions.
Cellular Slime Moulds (Acrasiomycotes): exist as individual amoeboid like cells with one nucleus each. Feed by ingesting tiny bacteria or yeast cells. When food becomes scarce, the cells release a chemical that causes them to gather together to form a pseudoplasmodium. This is a jelly-like mass, which produces a sporangia that releases spores.