What are they?
Before we go deep into the microscopic world where these creatures live, we need to know what they are. Copepods are small crustaceans who live in almost all freshwater habitats in the world
How Many Are There? (according to GA Boxshall)
How do we know how many copepods there are? Well, we don’t know, but we can make a reasonable estimate. The world is largely covered by oceans – 71% covered to be precise – to an average depth of 3.7km. This huge volume of water, 1.347 million cubic kilometers, represents the largest biome on planet Earth and it is home to copepods from top to bottom. The calculation runs like this:
• There is 1347 million cubic kilometers of ocean [1.347 x 10exp9 cubic km]
• 1 cubic kilometer = 1 x 10exp12 liters
• So 1.347 x 10exp9 cubic km = 1.347 x 10exp21 liters
Assuming just one copepod per liter (probably a gross underestimate) leads us to calculate that we share the planet with at least:
1,347,000,000,000,000,000,000 copepods
Boxshall GA. 1998