<<

Lecture: What is a ? A protist is a eukaryotic that has a nucleus and in moist surroundings.

Ways of grouping : -like, -like and -like

Animal-like : Like animal-like protists are (which mean they must obtain food by consuming other ), they are unicellular and are categorized in four different ways. Protozoans with Pseudopods, Protozoans with cilia, Protozoans with flagella and Other Protozoans.

Protozoans with Pseudopods- they move and feed by using Pseudopods (false foot). The Pseudopods feed by surrounding the food with two Pseudopods, then the two Pseudopods join together to trap the food.

Protozoans with cilia- they use cilia to move, collect food and to sense the environment. Cilia are hair like projections that move with a wave like motion.

Protozoans with flagella- they use flagella to move, they can have from one to eight flagella to help them move.

Other Protozoans- these protozoans are characterized more by the way they live than by the way they move. These protozoans, known as sporozoans, are parasites that feed on the cells and body fluids of their hosts. They move in a variety of ways

Fungus-like protists: Fungus-like protists are heterotrophs, they reproduce by producing and they are able to move at some point in their span. There are three types of fungus-like protists: water , downy mildews and slime molds.

Water molds and Downy mildew- both live in water or moist places. They grow as tiny threads that look like a fuzzy covering. They attack animals and crops such as potatoes, cabbages, corn and grapes.

Slime molds- live in moist and on decaying and trees. They come in many different colors. They move by forming pseudopods. Slime molds feed on and other .

Plant-like protists: Commonly called , they are . They can live in soil, on the bark of trees, in fresh water, and in salt water. Most of the oxygen on is produced by algae. Plant-like protists can vary in size, the can be unicellular, can be groups of unicellular organisms that live in colonies ore they can be multicellular organisms such as seaweed. There are several types of plant-like protists: Euglenoids, , , , and .

Euglenoids- found mostly in fresh water. They can act as heterotrophs when there is no sun light available. They have a and they have an eye spot that has that is sensitive to light to help them recognize which way the light source is. Question: how can this eye spot be important to an ?

Dinoflagellates- unicellular algae covered in stiff plates that exist in many colors. They have two flagella that help them move and many of them glow in the dark.

Diatoms- unicellular, with glasslike walls. Some float on fresh and salt water, while others attach to rocks in shallow water. They move by oozing slime out of their and glide in the slime. They are a food source for heterotrophs. When diatoms die they fall to the bottom of and lakes. They then form a layer called , which is used in toothpastes, scouring products, swimming pool filters and insecticides.

Green algae- contains green and can be unicellular, can form colonies and can be multicellular. Most live in fresh and salt water but can be found at the bases of trees and in moist soil.

Red algae- all are red multicellular seaweed. Can be found at depths of 260 meters below level in the . A substance known as carrageenan found in red algae is used to make ice creams and hair conditioners. Some Asian cultures eat fresh red algae.

Brown algae- have brown pigment but also contain green, yellow and orange pigments. Have many plantlike structures like holdfasts (which anchor the algae to rocks), stalks and blades. They also have bladders filled with gas to help them stay upright. Substances called aligns are extracted and used as thickeners in food such as puddings and salad dressings.