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dinoflagellates

OLogy Series
biology
card
140

dinoflagellates

OLogy Series
biology

Dinoflagellates are tiny, one-celled organisms that live in oceans and freshwater ponds, rivers, and streams. Some dinoflagellates are like plants, depending on sunlight and basic nutrients for growth. Others are like animals, eating bacteria and microscopic organisms. They are part of a large group of diverse organisms that have been classified as "protoctists."

Blooming Algae!
Sometimes, particularly in warmer months, dinoflagellates can reproduce quickly and abundantly. This "bloom" leads to a dense population of dinoflagellates -- as many as 20 million cells per liter of water. The high concentration of dinoflagellates gives the water a red, golden, or brown hue, known as "red tide." Red tides are an amazing sight, but they can also be very dangerous. Since some species of dinoflagellates release poisons, a "bloom" can create a toxic red tide. The poisons accumulate in fish, particularly shellfish, causing nerve damage or sometimes death. Poisons can also be passed on to other fish and to humans who ingest the shellfish. Red tide can cause major health problems, but most countries monitor the levels of toxins in shellfish during the most dangerous months.

Dinoflagellates swim by:

doing the breaststroke

expelling air out of a small hole

using two long, hairlike arms

Are you right?

Correct!

Dinoflagellates swim using two hairlike arms called "flagella," formed from long protein strands. These flagella propel the cell through the water, making it spiral as it moves.

"Armored" species of dinoflagellates have:

thick, rigid plates

steel arms

a hard metal casing

Are you right?

Correct!

"Armored" dinoflagellates are covered with rigid plates made of cellulose. These plates overlap so they can slide apart when the cell expands.

Some dinoflagellates flash like night-lights when they're agitated or threatened.

Fact
or
Fiction
?

Fact

Some dinoflagellates give off quick flashes of light when disturbed by fish, waves, or ships. This chemical light is called bioluminescence.

dinoflagellates
Size: microscopic to 2 millimeters
Habitat: oceans, freshwater ponds, rivers, and streams throughout most of the world
What they can do: make food from the Sun's energy; flash light through bioluminescence
Characteristics: some have protective, plate-like shells; swim in a spiral; can cause water to look golden or red

Image credits: courtesy of Susan Carty.