What is a "porpoise"?

Porpoises are small, toothed whales that are closely related to dolphins. They have a streamlined body with a dark upper surface and a lighter underside, and typically have a short beak and a rounded dorsal fin. Porpoises are known for their playful behavior and agility, often riding the bow waves of boats and performing leaps and flips. They are skilled hunters, feeding primarily on fish and squid. Porpoises are found in various oceans and seas around the world and are known for their social nature and complex communication skills.