Why did freshwater animals survive the K-Pg impact winter better than land animals?

Answer: They ate dead organic matter

They ate dead organic matter ✓ — Correct! When sunlight was blocked after the asteroid impact, plants stopped growing on land. Land animals that relied on fresh plants or herbivores starved. But freshwater animals could eat detritus—dead leaves, carcasses, and other organic matter washed into rivers and lakes. This stored food kept the aquatic food web running for months or years, giving them a survival edge.

They lived in warmer water — Wrong. While water does hold heat better than air, the key advantage wasn't temperature. Many freshwater habitats actually cooled down. The real reason is that freshwater food webs could tap into a reservoir of dead organic matter, which didn't depend on sunlight for production.

They needed less oxygen — Wrong. Oxygen levels in water can drop when organic matter decays, but that would stress rather than help animals. The survival advantage came from food availability, not oxygen. In fact, some land animals could hold their breath or had efficient lungs, but they still starved.