Platypus fur is dense and waterproof, with two layers: a soft underfur and longer guard hairs. This keeps skin dry and insulated in cold waters. Fur traps air for buoyancy and thermal regulation. Grooming maintains fur waterproofing. The dense coat is essential for survival in rivers and streams. Fur also camouflages the animal from predators. High-quality insulation reduces energy expenditure.
Waterproof fur is critical for thermoregulation and survival.
Fur adaptations reflect evolutionary pressures in aquatic environments.
Dense fur allows platypuses to thrive in temperatures ranging from 5–25°C.
Smithsonian National Zoo (si.edu)