Two hearts pump blood through the gills and one pumps it around the rest of the body. Their blood is blue because it carries oxygen with a copper-based protein called hemocyanin.
Nature & Animals · Did you know?
Octopuses have three hearts
More facts
Lightning is about five times hotter than the surface of the Sun
A lightning channel can reach around 30,000 degrees Celsius. The surface of the Sun is about 5,500 degrees Celsius.
Read the full fact →A day on Venus is longer than its year
Venus takes about 243 Earth days to spin once on its axis, but only about 225 Earth days to orbit the Sun.
Read the full fact →Sunlight takes about eight minutes to reach Earth
Light travels roughly 150 million kilometres from the Sun to Earth in about 8 minutes and 20 seconds.
Read the full fact →