Shark

Shark is a fish with a skeleton made of cartilage instead of bone, giving it a flexible, powerful body. Over 500 shark species swim in oceans worldwide, ranging from gentle whale sharks that filter plankton to swift great whites that hunt seals. Sharks have lived for more than 400 million years, surviving several mass extinctions thanks to keen senses and adaptable bodies. Their streamlined shapes, sharp teeth, and strong tails help them move silently through the water, while rough skin covered in tiny denticles reduces drag like a natural wetsuit.

Sharks rely on sophisticated senses to locate prey. Excellent vision works even in dim light, and sensitive smell receptors detect a drop of blood from far away. An extra sense called electroreception lets sharks feel faint electric signals produced by muscles of nearby animals. Some species, like hammerheads, use their wide heads for better steering and improved electrical detection. Not all sharks are fierce hunters; nurse sharks suction shellfish from sandy bottoms, while basking sharks glide slowly with mouths open to filter microscopic food.

Shark reproduction varies widely. Many species lay leathery egg cases nicknamed “mermaid’s purses,” which anchor to seaweed until the pups hatch. Others give birth to live young, called pups, that swim on their own immediately. Sharks grow slowly, produce few offspring, and often take years to reach maturity, making them vulnerable to overfishing. Scientists tag sharks with satellite transmitters to track migrations and learn where they breed, feed, and rest.

Sharks support healthy oceans by keeping prey populations balanced and removing weak or sick animals. When sharks decline, prey species can grow out of control and harm coral reefs or seagrass beds. Unfortunately, millions of sharks are caught each year for meat, fins, and liver oil. Some are also trapped accidentally in fishing nets. Conservation efforts include creating marine protected areas, banning finning (removing fins and discarding the rest), and promoting sustainable seafood choices. Public awareness campaigns encourage respect for sharks instead of fear.

Students can explore shark science through virtual dives, aquarium visits, and citizen-science projects that log sightings. Engineers study shark skin to design faster swimsuits and airplane coatings. Artists and writers use shark stories to spark curiosity about the ocean. Learning how sharks sense the world, raise pups, and stabilize marine ecosystems shows why protecting them is vital for ocean health.