Over the last 450 million years, sharks have survived five mass extinctions, making them some of the oldest—and sturdiest—creatures still in existence today.  But a sixth mass extinction that many scientists fear is underway could be too much for these fierce predators. In recent years, overfishing and ocean degradation have pushed many shark species to … Continue reading The World’s Sharks Face a Gauntlet of Threats From Marine Heatwaves—and ‘Coldwaves,’ Scientists Say