Why do hippos sweat red?

Answer: Sunscreen and antibiotic secretion

Sunscreen and antibiotic secretion ✓ — Correct! Hippos don't actually sweat red. They ooze a thick, oily fluid that starts out colorless and turns red-orange as it meets the air. The red pigment, called hipposudoric acid, acts like a built-in sunscreen by soaking up UV rays, and it also has antibiotic properties that keep wounds and waterborne bacteria from causing infection. At the same time, the fluid moisturizes their hairless skin and helps stop it from drying out and cracking. People once thought it was blood, which is why it's nicknamed 'blood sweat,' but it's really a multipurpose skin protectant that lets hippos spend so much time in the water and sun.

Red color attracts mates — Wrong. The red fluid isn't a mating display; it's a protective skin secretion. The pigments absorb ultraviolet light and help prevent infection, which matters for an animal that spends its days in strong sun and murky water.

Warning signal to predators — Wrong. The red fluid isn't a warning to predators; it's a skin protectant. Hipposudoric acid absorbs UV light and fights bacteria, helping the hippo's bare skin stay healthy in sun and water.