Here's why:
* Predators have different senses: Sloths' primary predators, like jaguars, have much stronger senses of smell than humans. They can easily detect prey even with strong odors.
* Other defense mechanisms: Sloths have other, more effective defense mechanisms, such as camouflage, slow movements, and sharp claws.
* Not the main purpose: The algae is more likely a symbiotic relationship, where the algae benefits from a safe place to live and the sloth gets a camouflage benefit.
So, while the smell of sloth fur might be off-putting to humans, it's not a primary means of defense against predators.