Plant-like Protists“AKA”Algae

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Green algae:

Volvox Brown algae: kelp

Red algae

Red tide-dinoflagellates

Journal 3 Some 300 years ago, most of a ship’s crew burned with

fever, then shivered with chills even though it was very hot. For a day or two, they seemed to improve. But the fever returned, and the condition of the men worsened. The captain turned to the ship’s doctor. He had to know what was wrong and what to do. The doctor shook his head. “It is the air, my captain. The men have the bad-air fever!” It took 100’s of years to discover that the fever comes from infection by tiny protozoa carried by mosquitoes, not from bad air. We still call the disease mal-aria- malaria.

What are some things humans have done to protect themselves from malaria? What do you think could be done?

Why is it sometimes a benefit to have sickle-cell anemia if you live in an area prone to malaria infections??

General Characteristics of Algae.

• classified by color (pigment)• form the base of the aquatic

food chain as phytoplankton• produce much of the Earth’s

oxygen• unicellular • multicellular• Some are colonial• Photosynthetic • Freshwater and marine

Human uses of Algae• major food source for

marine life• Oxygen production~50%• Found in ice cream, salad

dressings, pudding, candy bars,

• Chemicals extracted from algae are used to treat High BP, arthritis, stomach ulcers.

• Chemicals from algae used to make plastics, waxes, deoderants, paints

• Many varieties rich in vitamin C and iron.

Unicellular Algae.• Euglenophyta: • Closely related to

animal-like protists• move with flagella,

respond to light with eyespot

• Photosynthetic• No cell wall- pellicle

instead – tough, flexible membrane

• Asexual repro. – binary fission

Unicellular algae.• Phylum dinoflagellata • Have two or more flagella• Many are bioluminescent = they

glow• Move in a spinning motion• Causes red tides:

– Gonyaulax catenella produces a nerve toxin

– Nerve toxin released within the consumer once eaten

– Bioaccumulation within higher order consumers occurs when multiple numbers are eaten

– nerve toxin also present in the water – You can’t swim or fish during RED

TIDE

Red tide

Gonyaulax catenella

what causes a red tide?

• Red tides usually occur south coasts in late summer and fall.

• cold, nutrient-rich water rises up from the deeper regions of the ocean to the surface, a process known as upwelling.

• dinoflagellate cysts come up with the upwelled water.

• the germination of the cysts is triggered by the ideal conditions (cold water, light)

• The rapid increase in dinoflagellate numbers, sometimes to millions of cells per litre of water, is what is known as a "bloom" of phytoplankton.

Unicellular Algae

• Phylum Bacillariophyta: Diatoms

• Marine autotrophs eaten by many other marine animals

• Have glassy shells, harvested to use in abrasive cleaners, was used for toothpaste

• Store oils giving fish a strong “fishy” taste when they eat them

• Among most abundant organism on Earth

• Shells are made of silicon- the main ingredient in glass

Why do you think diatoms are not used in toothpaste anymore?

Uni & Multicellular Algae• Phylum Chlorophyta- means green

plants in greek• “AKA” Green algae• Undergo photosynthesis• Usually found in freshwater near

the surface• Some have special adaptations for

floating called air bladders• Wide variety of forms: filaments,

sheets, spherical, and colonies• Largest phyla of algae in numbers• Some multicellular (ulva), colonial • Ex. Volvox, Spirogyra and ulva-

also known as sea lettuce

Volvox

Spirogyra

Ulva

Multicellular Algae• Phylum Rhodophyta: red algae• Marine seaweed• Attach to rocks at bottom of

ocean• Able to live deep due to having

red accessory pigments called phycobillins (absorb blue wavelengths of light)

• EX. Corraline algae, Irish moss

• Phylum Phaeophyta: brown algae• Most are marine• Largest and most complex algae• Commonly called Kelp• Grown in kelp “beds” providing

shelter for fish

What part of the color spectrum is this reflecting?

Kelp

Quiz 1. Which algae type is commonly called kelp? a. brown b. green. c. red2. Which algal group is the largest in numbers? a. brown b. green c. red3. Which algae have glassy shells and no

flagella? a. brown b. diatoms c. dinoflagellates4. Which algae produce toxins when they

bloom causing red tides? a. diatoms b. dinoflagellates c. red5. How are algae classified? a. shape b. pigment c. movement