Sunday, March 31, 2013

Herbivory's advantage: food is all around

In the mood for a salad (hold the dressing)? Three times a day, every day? Who in their right mind eats just greens all the time?

koalas eat greens all the time!
If you read the last post, you already know - it's Herbivores, the animals that specialize on eating plants.

The last post introduced the vertebrate herbivores (insects are another big plant-eating group, as all gardeners know!), which include some of the world's largest and most charismatic creatures.

Why is that? Why do herbivory and body size seem to go hand in hand, at least among mammals?

To find out, read on!

Large appetites

The quick answer is that herbivores eat plants, which is important for several reasons: (1) Plants are common (), and (2) they don't run away (). However, (3) they can fight back in their own way: getting energy and nutrition from plants is tough business that requires serious processing and digestion effort (). I'll cover that last one in the next post.

life is good for grazing wombats in NewSouthWales
The first reason is obvious: under normal conditions (no drought or record snowfall...), herbivores don't need to use energy searching for and chasing down prey and can therefore grow to be much larger than meat-eating carnivores.

This is especially true for folivores, the herbivores specializing in leaves and grasses.

Think how relaxed you feel watching cows, sheep, horses, antelope, or even manatees or wombats graze on vegetation. There is no rush, no confusion, and no fighting.

So long as there is some tasty grass or bushes around, herbivores just need to get on it and EAT. And they do!

large but gentle eland grazing at De Hoop Nature Reserve, South Africa

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