I’ve realized this ever since I was 11 and yet it still confuses me why sharks, particularly great white sharks, only bite or sometimes attack humans out of curiosity. Meanwhile crocodiles will always attack, kill and eat humans when they get the chance, similar to Komodo dragons. What are the biological niches behind all of this?
In: Biology
Part of it has to do with the development of the brain. Evolutionarily speaking, crocodiles are still basically dinosaurs, with very simple brains that are mostly instinct-driven. Sharks, being very very different from crocodiles, have an entirely different nervous system that is far more complex, and allows for things like curiosity.
Basically, everything is food to a croc, but a shark is smart enough to be curious and confused.
Predators have a tenuous life and don’t waste effort on unfamiliar prey. Crocodiles have seen humans paddling in rivers for thousands of years. Big sharks mostly live in deep ocean and aren’t so familiar with us.
It’s all about how we compare to their normal prey.
The normal prey of your standard predatory shark is fish and marine mammals. In particular, when sharks bite surfers or swimmers they are usually expecting to get a seal or sea lion.
In contrast, the normal prey of crocodiles is fish and terrestrial mammals. When crocs attack humans they are generally waiting near the water and grabbing whatever deer or antelope or pig they can sneak up on while it is coming down to the water.
This is important because seals and sea lions usually have an nice thick layer of blubber…and this energy rich fat is a valuable resource for sharks. It’s what they want. Instead, a shark biting a surfer gets a bony mouthfull of low-fat swimmer, probably covered in a wetsuit. Not very appetizing, so it’s no surprise they move on. A croc, on the other hand, is inspecting something that tastes very much like its normal prey…just another foolish mammal come down by the river.
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