Protists Part II

Algae: Plant-like Protists

A. Euglenoids1. Example: Euglena

2. Traits similar to plants:

a. cell wall

b. Chlorophyll

3. Traits similar to animals:

a. Move with flagella

b. Respond to light using eyespot (light sensitive organelle)

Gullet

Chloroplast Carbohydrate storage bodies

Pellicle

Contractile vacuoleNucleusEyespotFlagella

Structures of a Euglena

Euglena undergoing fission.

B. Diatoms

1. Marine (ocean) autotrophs

2. Glassy shells used for abrasives

3. Form oils – give fish a strong taste

C. Dinoflagulates

1. Have 2 flagella

2. Some produce toxins when they bloom; called red tides.

* kills or sickens fish

D. Red Algae

1. marine seaweed

2. attaches to rocks at the bottom of the ocean

E. Brown Algae

1. most are marine

2. usually called “kelp” or seaweed

F. Green Algae

1. Have chloroplasts

2. Photosynthetic

3. Live in fresh water

4. Make up photoplankton = the base of the fresh water ecosystem food chain

5. Many forms – filaments, sheets, colonies

Volvox

Beneficial Plant-like Protists Diatom shells are used in toothpaste,

metal polishes, and added to paint to give it sparkle.

Kelp provides habitat for many organisms.

Important part of the food chain, especially in the oceans

Algae releases oxygen into the air

Harmful Protists

Dinoflagellates kill fish and other organisms with toxin during red tides

Some cause disease such as malaria, amoebic dysentery, & sleeping sickness

Algal blooms (overpopulation of some algae) can cause oxygen shortage or limit the amount of sunlight that other organisms need

Red Tide

Red tides occur when there is a rapid increase in the population of these single-celled organisms. Red tides are part of the normal plankton production cycle, but sometimes the process will result in a large fish-kill and die-off of other aquatic animals.

How this bloom actually kills aquatic life is still uncertain. Some scientist believe toxins from the red tide organisms kill other organisms but disagree on how the toxins are produced and function. Another theory identifies the source of kills as the rapid biological production that depletes the dissolved oxygen in an area and makes it unsuitable for other organisms.

Red tide is a phenomena that affects beaches around the world. 

It is a discoloration of sea water caused by single-celled organisms called dinoflagellates, which live in coastal waters and rivers.