50 years ago, our relationship with the ocean changed. Peter Benchley published Jaws in 1974, casting great white sharks as monsters of the deep who attack humans for no reason.
Unfortunately, sharks have found it difficult to overcome this reputation. So, let’s spend a little time talking about great white sharks and their importance to our oceans.
Also known simply as white sharks, great white sharks (Carcharodon carcharias) are the largest predatory fish in the ocean. They get their name from their coloration: great whites have a white belly and a dark gray or brown back. This serves as hunting camouflage, as the ocean gets lighter as you look up towards the surface (and towards the sun) and darker as you look down. When potential prey looks up to the ocean’s surface, an overhead great white’s light belly blends in with the surrounding water.
Great white sharks are a type of mackerel shark. Sharks in this order are generally torpedo-shaped, with conical snouts and keels at the base of their tails. Mackerel sharks also have mouths that reach past their eyes. Great whites are the largest type of mackerel shark and can get pretty big! They can grow to about 20 feet (6 meters) long and weigh over 4,000 pounds (1,814 kilograms). Even their pups are large: great white sharks are ovoviviparous, which means their eggs hatch inside the mother, where the pups continue to grow until the mother gives birth. Great white pups are born at about 4 feet (1.5 meters) long.
Exactly where you can find great whites depends on their age. In general, younger great whites are found closer to the coast, while older individuals are more likely to be found in the open ocean. Great white sharks are typically found in temperate and subtropical water. They are also partially warm-blooded and can keep their internal body temperature higher than the surrounding water. This means they can be more active in colder waters than cold-blooded species. Still, they prefer to live in water that’s 50 to 80 degrees Fahrenheit (10 to 27 Celsius). Great whites will often migrate seasonally to stay in their preferred temperature range.
Smile!
Great white sharks have a distinctive smile full of sharp, 2.5-inch-long serrated teeth. The typical great white has about 300 teeth at any given time. These teeth are generally broad and triangular, with the teeth on the lower jaw slightly narrower than the top ones. The bottom teeth keep the prey in place while the upper ones tear into flesh.
Although great whites have a lot of teeth in their mouths, most aren’t used to bite at the same time. Instead, the teeth are arranged in up to seven rows and are part of a conveyor-belt-like system. As teeth in the front wear out, they are replaced by new teeth from the back. Great white sharks continue growing new teeth throughout their lives.
Apex predators
Great white sharks have highly tuned senses to help them find prey. Perhaps most important is their sense of smell: a great white can smell a single drop of blood in 100 liters of water! Put another way, they can smell a drop of blood in 10 billion drops of water. They can even stick their heads out of the water to smell land prey like seals. Great whites can also find prey through electrosensation. By sensing electric currents, they can “hear” the heartbeats and other movements of prey animals.
Once prey is located, great whites can rocket through the water to catch it. Thanks to its torpedo-shaped body and powerful tail, a great white can swim about 35 miles an hour (50 kilometers an hour). They then bite their prey with a bite force of up to 1.8 metric tons. This is one of the highest bite forces on the planet and nearly 25 times more powerful than a human’s bite. This force, combined with serrated teeth, quickly leads to huge blood loss and massive trauma.
Great whites are opportunistic feeders who eat fish, sea turtles, and even birds. Their favorite foods, though, are mammals with a lot of fatty tissue (i.e., dolphins, whales, and seals). This is also why great whites don’t usually eat humans – we’re too lean and bony! Scientists think that most human shark bites are exploratory, with the shark using its mouth to figure out what the creature swimming in the water is. Once they discover that the human isn’t fat like a seal, great whites swim away to find better food.
Sharks are out there!
Even though they don’t want to eat us, chances are there’s a shark around if you’re swimming in the ocean. Around New England, for instance, there’s been more shark sightings close to shore. This could be because the seal population is increasing or because the ocean water has been warming due to climate change (or both!).
Although it might make you nervous, it’s ultimately a great sign that more sharks are around. Great whites play an essential role in keeping populations of prey animals in check. Plus, the reality is that great whites are very unlikely to bite you. There were only 69 unprovoked shark bites worldwide in 2023 (and that includes bites from sharks other than great whites, too!). Most of the time, they swim away when humans get close.
Still, you should be prepared if you see a shark in the water. Great whites and other sharks should be treated like other wild animals: if you see one, stay calm and give it space. If the shark is making you uncomfortable, calmly leave the water. To minimize shark bites, you can also avoid swimming if you’re bleeding and don’t wear shiny jewelry (it can look like fish scales). If a shark does bite you, fight back by hitting it in sensitive spots, like eyes and gills.
But remember: it’s doubtful a great white or other shark will bite you! We’re too lean to be a good meal for a shark!
Resources
Leave a Reply