A protist is a single or many celled organism that lives in moist or wet surrounding. All protists have a nucleus and are therefore eukaryotic. Scientists hypothesize that the common ancestor of all protists was a one celled organism with a nucleus, mitochondria, and other cellular structures.
Plant like protists are known as algae. Some species of algae are one celled and others are many celled. All algae can make their own food because they contain the pigment chlorophyll in their chloroplasts. Algae are divided into six main phyla according to their structure, pigments, and the way in which they store food.
1. Euglenoids have the characteristics of both plants and animals. A typical euglenoid is the Euglena.
2. Bacillariophyta are found in the freshwater and salt water, a common example is the diatoms, which form the coral reefs.
3. Dinoflagellata contains species called dinoflagellates that have a red pigment. They are commonly found in freshwater and salt water.
4. Chlorophyta is the phyla where the algae contains chlorophyll and produces nearly half of the oxygen we consume; spirogyra is one example of this phylum.
5. Rhodophyta has red algae as its member and it is used in pudding and toothpaste.
6. Phaeophyta are many celled and found growing in cool saltwater environments. Kelp is an important source of food for many fish and invertebrates. The thick texture of ice cream and marshmallows is produced by algin, a product found in these algae.
Animal like protists are one celled, complex organisms living in water, soil, and in both living and dead organisms. They are called protozoans. Protozoans are separated into groups--- rhizopods, flagellates, ciliates, and sporozoans.
1. Rhizopods move about and feed using temporary extensions of their cytoplasm called pseudopods. Amoeba is one such example.
2. Zoomastigina are protozoans that move using flagella. Most species live in fresh water.
3. Ciliophora move using cilia. Cilia are hair like structures that extend from the cell membrane, paramecium is one such example.
4. Sporozoans are parasitic organisms. They have no way of moving on their own. All are parasites that live in and feed on the blood of human and other animals.
Fungus like protists include several small phyla and have features of both protists and fungi. Slime molds and water molds are fungus like protists, they get their energy by breaking down organic materials.