Since the Jaws theme song rumbled into theaters and Bruce the great white shark swam across our screens, pop-culture around sharks has been riddled with misconceptions about these incredible animals. While it’s easy to think of these apex predators as indestructible, sharks are vulnerable and in need of our help. We talked to Shedd’s Director of Marine Research, the shark-obsessed Dr. Steve Kessel, to get to the bottom of five of your biggest questions about one of the ocean’s, and planet’s, greatest predators.
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1: Are all sharks as aggressive and scary as people portray them to be?
No. If sharks were as aggressive and scary as they’re often portrayed to be, people simply would never be able to swim in the ocean. Most shark-and-human interactions in the wild end with the shark getting startled and quickly swimming away. If you want to see a more realistic interaction between sharks and humans, watch as divers clean the shark habitat in Wild Reef. You will see a lot of sharks leaving divers in peace to clean the habitat.
On the other side of the coin, it’s sharks that should consider humans scary, with around 100 million sharks killed by humans in fisheries every year. These high levels of mortality have led many populations to decline, with one quarter of all elasmobranch species — sharks, rays, skates and chimaeras— currently under threat of extinction. We need to change our perception of sharks, and they need our help to reverse population declines and sustain them long into the future.
2: Do sharks actually die if they stop swimming?
No shark species will instantly die if it stops swimming, though many do need to swim forward to breathe. These species are known as “ram ventilators” and breathe by flowing water through their mouths and over their gills as they swim forward.
Another tactic many shark species use to breathe is called “buccal pumping.” Instead of swimming forward, they open and close their mouths or use their ‘spiracles’ — specialized small openings located just behind the eyes that act like a snorkel, allowing the animal to quietly pull water into its respiratory system and over its gills even when the mouth is closed —to pump over their gills. You can see the differences between these two breathing types at the shark habitat in Wild Reef. Sandbar sharks are ram ventilators and, all day and night, they will never stop swimming. Whereas if you watch the wobbegong sharks — buccal pumpers — that rest on the sandy bottom where you can look closely to see their spiracles opening and closing as they pump water over their gills.
A wobbegong shark pumps oxygen over its gills, while remaining still.
3: What's the oldest shark in history?
Sharks are a lot older than people realize. Not only can many species live longer than 80 or even 100 years (that’s real human years, not like dog years!) — many aren’t even able to reproduce for many years, commonly starting after 10 years and several species over 25 years. This slow crawl to reproductive maturity is significant when you consider how long it can take for vulnerable shark populations to rebound from years of overharvesting.
The most extreme age example that we know about is the Greenland shark, the true old-timers of the shark world. The largest individual sampled was a 17-foot-long female estimated to be between 272 and 512 years old!
Photo by: Shedd Aquarium/Heidi Zeiger
4: How is Shedd participating in shark conservation?
As part of our broader marine research program, Shedd’s Shark and Ray Research program has three main goals: 1) monitor biodiversity and abundance over time; 2) describe the movements and migrations of sharks relative to protected areas and fisheries threats; and 3) assist the recovery of some of the world’s most imperiled species.
Shedd is a leading member of SharkRay 360, an international consortium of shark and ray experts focused on conservation strategies for the critically endangered bowmouth guitarfish. Shedd is also a founding partner in an international initiative to raise and release aquarium-born, endangered zebra sharks in Raja Ampat, Indonesia. ReShark’s STAR project aims to bolster zebra shark populations in their native range. Shedd experts have lent their years of education, research and dedication to develop the project.
5: How long have sharks lived on our planet?
Sharks are one of the longest-surviving groups of vertebrates on Earth. The earliest sharks originated around 450 million years ago, further back than the origin of dinosaurs (around 250 million years ago), and even long before the origin of trees (around 350 million years ago). This makes sharks some of the most impressive survival experts this planet has ever seen — they have survived FIVE mass extinction events!
It is only now, in the age of humans, that so many species are under threat of extinction. Since this is the direct result of our activities, we are wholly responsible for reducing these threats and ensuring their long-term survival.
Still have questions about sharks? Visit Keep Sharks Swimming to get the latest conservation tips and shark news.
Meet the Sharks
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