Kingdom Protista

Protists, What are they?

Protists are defined by what they are NOT…

Eukaryotes that are not plants, animals, or fungi

Scientists believe they were the “1st eukaryotic organisms”

Most are unicellular (algae exception) Many are “aquatic” Very diverse kingdom

Protists and the Evolutionary Tree

Animal-like Protist

Heterotrophic organisms Distinguished by how they move:

1) flagella: long “tail-like” structure2) pseudopods: “false feet”

extensions of cytoplasm 3) cilia: tiny “hair-like” structures

beat in unison 4) some immobile

Sarcodines Animallike protists

use pseudopods for feeding and moving

Ex) Amoeba

Food

Ciliates Animallike protists

use cilia for feeding and movement

Ex) Paramecium

Zooflagellates

Animallike protists swim using flagella

Trypanosoma protist spread by the bite of tsetse fly causes African Sleeping Sickness

Giardia can contaminate water and cause digestive problems

Trichonympha lives in mutualistic relationship with termites

Sporozoans

Animallike protists that do not move on their own and are parasitic

Plasmodium sporozoan causes malaria Sporozoan parasite is carried by female Anopheles

mosquito

Plasmodium Life Cycle Mosquito bites human

parasite injected• Parasites invade liver

reproduce and develop• Liver cells burst and

parasites move red blood cells

• RBC burst person experiences anemia, fever, chills, may result in death

• Parasites may then move into other RBC or are picked up by mosquito and transferred to another person

Plantlike Protists: Unicellular Algae

Photoautotrophs- contain chlorophyll and carry out photosynthesis

Often called “phytoplankton”- small photosynthetic organisms near the surface of ocean

Phytoplankton carries out photosynthesis releasing oxygen into the atmosphere

Phytoplankton important food source for many “filter feeders”

Euglenophytes

Plantlike protists that have flagella chloroplast, but no cell wall.

Ex) Euglena

Diatoms

Produce thin, delicate cell walls made of silicon

Used in toothpaste, paints on license plates, dynamite

Plantlike Protists: Algae

Red Algae- mostly multicellular algae contains special pigments that allows it to live deep areas of water

Brown Algae- all multicellular and most are found in marine environments (ex: Kelp)

Plantlike Protists: Algae

Green Algae- some are unicellular, some form colonies, few are multicellular

Chlamydomonas

Volvox

Sea Lettuce

Humans and Algae

• Humans understand many beneficial uses of algae:1) Used to make nutrient agar2) Used as ingredient in ice cream, pudding, salad dressing, syrups3) Food source – humans and other animals4) Releases oxygen from photosynthesis

• Algae causes harm in “algal blooms” – depletes water of nutrients and oxygen

Funguslike Protists

Heterotrophic protists that absorb nutrients, but lack cell walls with chitin

Ex) Slime molds- found near moist, rotting logs and composts

Ex) Water molds – can be parasitic and cause “ick” in fish