II. Animal-like Protists : Protozoans Protozoan – a protist with animal like characteristics. A. Characteristics of Protozoans 1. Protozoans are heterotrophs. 2. Are unicellular. 3. Most are mobile. -Protozoa means “first animals”. -Are classified by movement.

B. Types of Protozoans Protozoans include 4 main phyla : 1. Zooflagellates 2. Sarcodines 3. Ciliates 4. Sporozoans 1. Zooflagellates (Zoomastigina) – animal-like protists that swim using 1, 2, or many flagella.

Characteristics of Zooflagellates -Most are unicellular. -Reproduction is sexual or asexual. -Zooflagellates live inside other organisms in long-term, symbiotic relationships, Ex : Trichonympha in gut of termites to break down wood. -Cause sickness, Ex : Trypanosoma gambiense : African sleeping sickness – multiplies in human blood & releases toxins. Symptoms : sleepiness, fever, weakness. Transmission : tsetse fly.

Sarcodines 2. Sarcodines (Sarcodina) – animal-like protists that use pseudopods for feeding & movement ---The Blob? Pseudopod – “False foot”. A temporary cytoplasmic projection used for movement & capturing food. -When moving, cytoplasm streams into the pseudopod, & the rest of the cell follows. This locomotion is called amoeboid movement or sometimes cytoplasmic streaming. -Some have shells that make up limestone, Ex : Foraminiferans (calcium shell) & Radiolarians (silicon shell).

Amoeba – the best known sarcodine -The best known sarcodine is the amoeba – flexible, active cells with thick pseudopods that extend out to the central mass of the cell. -Amoebas have no definite shape (constantly change form) & form hard cysts in poor conditions. -Amoebas reproduce asexually through binary fission. -The cysts of amoebas can be ingested in food and water & make people sick, Ex : Amebic dysentery.

Ciliates 3. Ciliates (Ciliophora) – animal-like protists that use cilia for feeding & movement. Cilia – short, hair-like projections used for movement. -Are the most numerous and diverse group of protozoans. -Live in fresh/salt water & form cysts.

Paramecium – the best known ciliate -One of the best known ciliates is the paramecium. -Some have Trichocysts – barbed structures for capturing food & protection. -Reproduction is sexual (conjugation) or asexual (binary fission). -Have 2 nuclei : A. Macronucleus – controls cellular activities & holds genetic material. B. Micronucleus – extra copy of DNA & is exchanged during conjugation.

Sporozoans 4. Sporozoans (Sporozoa) – animal-like protists that can’t move on their own & are parasitic, ex : Plasmodium causes malaria. Transmission : Anopheles mosquito. Transmission : Anopheles mosquito. -Are protozoans that have NO structures for movement – are non-motile. -Have complex life cycles that include sexual and asexual phases that occur in more than one host.