Whale shark off the coast of Alifu Dhaalu Atoll, Maldives (© Bachir Moukarzel/Amazing Aerial Agency)

Whale sharks are the biggest fish in the sea, but don't let the word 'shark' fool you. They're plankton-eating giants with no interest in humans. Found in warm waters from the Maldives and Mozambique to Mexico's Yucatán coast, they often show up in food-rich, calm waters. Their mouths can stretch over a metre wide, but they feed by suction, not biting. Each has a unique pattern of white spots and stripes—no two alike—used by researchers to track individuals. Their breeding patterns remain largely a mystery, but they are ovoviviparous, meaning pups hatch inside the mother before being born alive. Their story reminds us how much ocean life remains a mystery and how vital it is to protect what we already know is at risk.