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cyanobacteria

Have you ever seen pond scum—that thick, smelly layer of slime floating on the surface of the water? That's probably blue-green algae, known to scientists as "cyanobacteria." These tiny bacteria grow in soil, freshwaters, and seas around the world. They are a normal part of ecosystems on land and in water. But when they form in large groups, they can spoil the water and can even be toxic!

Stats

Common name: blue-green algae
Age: species similar to the ones we see today first appeared on Earth about 3.5 billion years ago
Size: you need a microscope to see it; groups are big enough to see with the human eye
Habitat: shallow water, marine and freshwater; damp areas; tree trunks; and in surface soils
Characteristics: pollution can help it grow; can cause a smelly, thick scum in water

Stumper

A mass of cyanobacteria in water is called a:

burst

bloom

bouquet

Correct!

A mass or group of cyanobacteria in water is called a bloom. Some blooms release poisons and contaminate the water. Agricultural waste can pollute waters and increase the growth of cyanobacteria.

Fact or Fiction

You can tell whether water contaminated by cyanobacteria is poisonous by the way it looks and smells.

Fact

Fiction

It can be impossible to tell whether water contaminated by cyanobacteria is poisonous just by smelling or looking at it. A sample must be taken and analyzed in a laboratory.

Fact or Fiction

Some kinds of cyanobacteria that live freely in the open water of ponds or the sea can float or sink, depending on how much light there is.

Fact

Fiction

Fact

Some kinds of cyanobacteria use gas sacs to alter their buoyancy. They can float to the water surface or sink to the bottom. This helps them get light and nutrients at the best times.

Image credits: main image, Hans Paerl, author. Licensed for use, ASM MicrobeLibrary.

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