How big (or small) could animals get?

WITH EVOLUTIONARY BIOLOGIST JV CHAMARY

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Animals come in a range of sizes. The smallest are from a group called Myxozoa, jellyfish-like parasites about one-hundredth of a millimeter long that are only visible under a microscope. Among vertebrates you would recognize with the naked eye, the smallest known to man is Paedophryne amauensis, a tiny frog that is just 8mm long.

How large can animals grow?

The heaviest beasts to ever walk the Earth were long-necked sauropod dinosaurs, known as titanosaurs. With a mass of about 50,000kg, titanosaurs weighed the same as 10 elephants and yet were still three times lighter than the largest species of all time, the blue whale, at 150 tonnes. Aquatic mammals often have a mass-to-volume ratio that matches the density of water, which provides neutral buoyancy and supports weights that can’t be reached on land due to size limits.

What limits total body size?