Sharks can glow in the dark, Sense electromagnetic fields

Sharks are far more varied than most people realize, with 500+ species ranging from tiny dwarf lantern sharks just inches long to whale sharks that can reach around 40 feet. Most shark species are actually under four feet, and scientists keep naming new ones as marine exploration expands. A big reason sharks look and move the way they do is their cartilaginous skeleton. Sharks have no true bones, and that lightweight structure, paired with large oil-rich livers, helps them stay buoyant. Even without bones, parts of their bodies still show up in the fossil record, especially teeth and dermal denticles. 

One of the best shark facts in marine biology is their “sandpaper skin.” Shark skin is covered in dermal denticles, tiny tooth-like scales that point toward the tail to reduce drag and turbulence. That structure helps sharks swim efficiently and has even inspired competitive swimwear designed to mimic shark skin texture for speed. Sharks also carry sensory “superpowers,” including electroreception through the ampullae of Lorenzini, which lets them detect electric signals and subtle temperature shifts. Hammerheads take it further, sweeping their broad heads over the seafloor like a detector to find stingrays. Add strong night vision thanks to a reflective layer called the tapetum, and you get a predator built for low-light hunting. 

Shark behavior gets even stranger. Some species use caudal luring, waving the tail to mimic injured prey. Others, like the epaulette shark, can “walk” along the seabed and even cross short stretches of exposed ground between tide pools. The Greenland shark pushes the limits of longevity, with estimates suggesting 250 years or more and possibly over 500, raising fascinating questions about deep-sea life and slow growth. Scientists often estimate shark age by counting bands on vertebrae like tree rings, but newer research shows that method does not work reliably for every species. Sharks can also surprise us cognitively: gray bamboo sharks can distinguish quantities, and Port Jackson sharks can learn to associate specific music with food. 

Some of the biggest misunderstandings come from shark myths and sensational media. The idea that sharks can smell a single drop of blood from miles away is not a fixed rule; scent depends on water currents, dilution, obstacles, salinity, temperature, and competing ocean smells. Shark reproduction is equally diverse and sometimes unsettling, from egg-laying “mermaids’ purses” to live birth with placental connections that leave a temporary “shark belly button,” to ovoviviparity where eggs hatch inside the mother. Sand tiger sharks can even have embryos that consume siblings in the womb, and rare parthenogenesis has been documented. Meanwhile, sharks replace teeth continuously, sometimes going through tens of thousands over a lifetime, and not all sharks must keep swimming to breathe thanks to differences like ram ventilation and spiracles. 

Shark conservation is the urgent backdrop to all these shark facts. With IUCN Red List reporting that nearly 40% of shark and ray species are threatened, pressures like overfishing, habitat loss, climate change, and bycatch are pushing many populations toward collapse. Public education can help, including visits to accredited facilities that highlight threatened species and promote responsible stewardship, such as Adventure Aquarium and other major aquariums that showcase shark diversity and conservation needs. Beyond science, sharks show up in culture as metaphors, villains, and even revered guardians, symbols of resilience and leadership in many traditions. When we remember sharks as apex predators that stabilize food webs and support ocean health, the takeaway is simple: protecting sharks is also protecting the living systems that ultimately support every breath we take.