Your 5 Biggest Questions About Sharks, Answered!
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. That public perception is not only incorrect, it also puts sharks at risk. 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.
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—which happen multiple times across the globe every day—end with the shark getting startled and quickly swimming away. If you want to see a more realistic interaction between sharks and humans, come to Shedd on a Monday, Tuesday or Thursday when divers clean the shark habitat in Wild Reef. There you will see a lot of sharks leaving divers in peace to clean the habitat.
On the other side of the coin, it is 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 and skates—currently under threat of extinction and several other species in decline. Not only do we need to change our perception of sharks, but they also need our help to reverse population declines and sustain them long into the future.
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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 oxygen-rich water through their mouths and over their gills as they swim forward.
There is another tactic many shark species can use to breathe called “buccal pumping.” By opening and closing their mouths, they “gulp” oxygen-rich water and pump it out over their gills. You can see the differences between these two breathing types at the shark habitat in Shedd’s Wild Reef exhibit. Sandbar sharks are ram ventilators and you can watch them as long as you like, all day and night, and they will never stop swimming. Whereas if you watch the zebra sharks—buccal pumpers—for long enough, they may rest on the sandy bottom where you can look closely to see their mouths opening and closing as they pump water over their gills.
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! For me this takes the term ‘respect your elders’ to a new level. All sharks should be respected since they play a crucial role in maintaining the health of our aquatic ecosystems, but I think we should bow to one this old.
4: How is Shedd participating in shark conservation?
As part of our broader marine research program, Shedd has a conservation research program focused on shark and ray populations in The Bahamas. We work with Bahamian partners, The Department of Marine Resources and The Bahamas National Trust to help protect some of the richest shark populations in the northwest Atlantic.
One area of research aims to assess the benefits of The Bahamas Shark Sanctuary for shark populations in The Bahamas in the broader northwest Atlantic region. It also aims to establish their relevance on the global scale—for example, by contributing to assessment of global reef shark populations: the Global FinPrint. Learn more about recent findings about shark success in The Bahamas that Global FinPrint data has led to.
5: How long have sharks lived on our planet?
Not only can sharks live to very old ages, but they are also one of the longest-surviving groups of vertebrates on our planet. 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). For me, 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 have been 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 (learn more about these threats and things that can be done to help save sharks).
Still have more questions about sharks? Check out this video of Director of Marine Research Steve Kessel, hosted by the Association of Zoos and Aquariums, as he answers other frequently asked questions about sharks (and rays!) on Facebook.
Meet the Sharks
These awe-inspiring predators are found across our oceans—and throughout Shedd Aquarium. Look closer at the sharks that call Shedd home.
Teens Turn Shark Detectives in Global Project
The “FinPrint Captain’s Corner” in Teen Learning Lab is a dedicated workspace for the world’s largest shark and ray survey, Global FinPrint.
Sharks at Shedd—Wild Reef
Wild Reef is home to more than 20 sharks such as the blacktip reef sharks and sandbar sharks, the slow-swimming zebra sharks, and sedentary bott...