Why do no other aquatic animals grow to a huge size like whales do?

Why do no other aquatic animals grow to a huge size like whales do?

Richard Swifte
Darmstadt, Germany

Although the largest fish is the whale shark, which can typically weigh 20 tonnes, closely followed by the basking shark, this is far exceeded by various whale species. The largest is the blue whale, which averages 150 tonnes.

The buoyancy of water enables ocean animals to grow to greater sizes than land animals, which need legs sturdy enough to support them. But several dinosaur species are estimated to have reached 70 or 80 tonnes, so it seems surprising that no modern sea creatures other …