Why are the biggest animals herbivores?

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0:00These mega-creatures meet their mega-calorie quota with something that’s super-abundant and

0:04requires almost no effort to procure: little pieces of grass and leaves.

0:08And sure, leaves and grass aren't very calorie dense compared to things other animals eat,

0:12but the giants’ giant digestive tracts can hold a LOT of them at once - we’re talking hundreds

0:17of kilograms. Plus, the bigger an animal is, the longer the food stays in its digestive system,

0:21and the more microbes there are in there to break it down. All of that means that

0:25the giants are able to wring a lot of calories from grass and leaves - enough

0:28to meet their huge calorie demands. The abundance and ease of finding

0:32leaves and grass are why - at least on land - you see the same pattern in every biome:

0:36the very biggest animals are herbivores. Even back in the day when dinosaurs roamed the Earth, the

0:41biggest animals weren't predators like T. rexes – they were lumbering leaf-eating vegetarians.

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