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Misunderstood Monsters: The Truth About Sharks
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Misunderstood Monsters: The Truth About Sharks
Are sharks really just mindless eating machines?
By Judith Tarr
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Published on October 20, 2025
Photo by David Clode [via Unsplash]
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Photo by David Clode [via Unsplash]
The shark in popular culture is pretty much a mythical beast, on a level with the kaiju and the sea serpent. It’s a mindless eating machine, a total and unmitigated monster. All it wants is to turn you into swimmer tartare.
As with so much of what lives in the sea, we don’t know all that much about sharks. Research is ongoing and our knowledge increases steadily, but there’s still quite a lot of mystery. And quite a lot of shark species, too—over four hundred and counting.
Sharks range in size from the dwarf lantern shark at six inches (15cm) to the sixty-foot (18m) whale shark. The great white is not the biggest by far, and the tales of 25- and 30-footers (7-9m) are probably exaggerated. A large male great white runs around 11 to 13 feet (3.3-4m). The largest known male is named Contender, and was measured at 14 feet (4m) and 1653 pounds (750kg). He just showed up in the news, pinging his tag off the northeastern coast of North America.
Females are larger than males, at around 15 to 16 feet (4.5-5m). The longest reliably measured shark was around 20 feet (6m). Still plenty big, and plenty deadly; it’s the largest predatory fish on the planet. But Megalodon it’s not.
Not all shark species are distinctly sexually dimorphic, but many are. Females grow more slowly, and they eat differently—going for larger prey, the better to conceive and nourish their young. Bruce in Jaws is probably a she, and she’s hunting along the Cape to build herself up for making babies.
Some sharks lay eggs, some are ovoviviparous which means the eggs hatch inside the mom (and the babies feed on unhatched eggs and each other until they’re ready to emerge), and some, including great whites, have actual live births. No one had ever seen a newborn great white until very recently (and it’s a bit speculative, based on the evidence, because we have yet to see a great white giving birth). In further beautiful weirdness, a few species of sharks have reproduced parthenogenically, without the presence of a male.
Shark life spans are as varied (as far as we know) as their sizes and shapes. But since we’re into great whites, the range there is pretty similar to its cetacean analogue, the sperm whale. A great white can live about 70 years, and reaches sexual maturity somewhere around age 20. Contender, when tagged, was about 30 years old.
The grand champion in the shark longevity sweepstakes, as far as we know, is the Greenland shark, which has been recorded upwards of 250 years old. That’s far from the oldest living thing (some plants, jellyfish, and mollusks have lived much longer, and the hydra might be immortal), but it’s the oldest large vertebrate we know of, even older than the bowhead whale, some of whom have been found with harpoons dating back over 200 years to the golden age of whaling. Compared to this, humans are mayflies. So while Jaws is not accurate when it goes on about sharks living for thousands of years, it’s not as far off as we might think.
So what about the big question, the reason for all those gory movies—the shark attack? Are sharks really mindless aggressors? Is hunger their main motivation, with rage a close second? Are they, in a phrase, out to get us?
The answer is, pretty much, no. Sharks are apex predators. Some, like whale sharks, are like baleen whales: their prey is tiny and they eat a lot of it. Many, including the great white, eat bigger animals.
To a fifteen-foot shark, a fish the size of a human is a good dinner. The problem for us comes when she reads human activity in the water as fish activity. Especially if there’s blood, because sharks have an acute sense of smell and can detect blood from a long ways away.
She’s not deliberately targeting the human, any more than she’s targeting a fish or a seal. She doesn’t just attack for the sake of attacking. She’s hunting to eat.
What about boats? Again, sharks don’t randomly attack boats. The best explanation for when one does bite a hull is curiosity. “Big fish? Edible? CHOMP!”
Unlike the orcas that have been sinking yachts, sharks don’t gang up on boats unless there’s literally blood in the water. (The orcas may be playing, or it may be a teenaged fad. It’s probably not malevolent. They have not, so far, harmed any humans. Just their boats.) Also unlike the orcas however, they will bite a human who reads to them as prey.
These attacks in fact are quite rare, and fatalities even more so. You’re more likely to be struck by lightning than attacked by a shark. When attacks happen, they’re blown up out of all proportion. Jaws actually addresses this in the first half of the movie, when the mayor argues that if they close the beaches and publicize the first attack, people will panic and kill the tourist industry for the summer.
The film is spot on about the reaction to a shark attack. Long before Jaws and the book it’s based on, humans were terrified of sharks. There was a whole mythos around them, a persistent narrative: Sharks Kill. Sharks Eat. Sharks Bad. A similar, visceral terror used to be aroused by wolves, until the narrative shifted and more humans came to see wolves in a positive light.
With wolves, there’s the fluffy-fur aspect, along with pack loyalty and family bonds. Wolves are attractive, even with their terrible sharp teeth and their haunting howls. Plus we’ve domesticated a significant portion of the species and transformed them into house pets and loyal companions. Wolves are accessible. We can relate to wolves.
That hasn’t happened with sharks. There is nothing cuddly about a fish with sandpaper skin and far too many big, sharp, pointy teeth. To our eyes (and we are very visual animals), sharks are scary ugly. They look terrifying. There’s nothing there to hang our positive feels on.
So, are sharks really just mindless killing machines? Can sharks think? Do sharks think?
We don’t know. What we do know is that shark brains are proportionally as large as mammal brains, and have the same overall structure. That implies that they’re capable of a level of cognition above and beyond hunt-kill-eat. Possibly well beyond. Whether the implication is true, again, we don’t know.
Cetaceans are easier. They’re mammals, they raise and educate their young, and they communicate vocally, which we can relate to and try to understand. Sharks communicate through body language, movement, and chemical signals. Some vocalize, but as far as we can tell at this point, not with the sophistication of dolphin or sperm whale sounds.
Sharks are alien. They are not social animals in the way that cetaceans are. Jaws’ idea of the “rogue shark” is off base in that sharks in general, and great whites in particular, are mostly solitary. In that sense every great white is a rogue. At the same time, when they meet or mate, they appear to interact, and communicate, in complex ways.
We don’t know if, or how, young sharks learn to shark. They aren’t taught by their parents or relatives. Probably they learn by doing, though there is evidence that some species at least also learn by observing others. We’ve only just begun to study the nature and extent of their intelligence, how and how much they learn, and how or if they solve problems.
Again there’s an image problem. Octopuses are also non-nurturers, they’re complete aliens, their biology is bizarre by human standards, but also by human standards, they come down on the cute side of the equation. They’re accessible. We appreciate their aesthetic. We’re motivated to interact with them and study them.
Sharks are a harder sell. In the new but growing field of animal cognition, they are getting attention, but it’s very early days. All we can say is that they’re probably smarter than we think. How much smarter, time, and continued study, will tell.[end-mark]
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