In this exciting episode of Shark Academy, Jonathan explains how sharks deal with the fact that they are heavier than water and lack a swim bladder like other fish.
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You wouldn’t think that a shark tends to sink, but it does, and that stinks. I’m Jonathan Bird and welcome to Shark Academy!
Most bony fish have an organ called a swim bladder that they use to adjust their buoyancy. By adjusting how much gas is in its swim bladder, a fish can keep itself perfectly neutral so it doesn’t sink or float.
Sharks have no swim bladder, so they tend to be heavier than water and sink like a rock.
Some sharks, like the Wobbegong, have dealt with it by becoming bottom-dwellers.
Other sharks, like Blue sharks, have evolved very large pectoral fins to act as airplane wings. As the shark cruises gently through the water, the fins provide lift to keep the shark aloft.
Many sharks like the Basking shark have evolved massive, oily livers. The oil is more buoyant than water, and helps offset some of the shark’s density, to help keep the shark from sinking.
A few sharks, like the Sand Tiger and the Whale shark are known to gulp air at the surface. By putting some air in their stomachs, they don’t sink quite so much.
Not having a swim bladder gives sharks one big advantage over bony fish—the ability to rapidly change depth without worrying without bursting the swim bladder. If a bony fish ascends faster than it can remove gas from the swim bladder, it will literally explode!
Check out our other exciting Shark Academy episodes to learn everything about sharks! You can also join my adventures exploring the underwater world! Check out Jonathan Bird’s Blue World! And don’t forget to subscribe!
