It’s the 27th annual “Shark Week” on cable’s Discovery Channel. (You may have noticed that The Maritime Aquarium is the local sponsor of “Shark Week” on Cablevision!)
Although the original intent of “Shark Week” was to share helpful educational information about sharks, some of the programming seems to have slipped toward the over-hyped and dramatic and scary (and, in the case of Sunday night’s big kickoff, fictional and silly).
We’ll use the themed week to offer some not-so-terrorizing – and true – insights into the sharks living at The Maritime Aquarium.
Did you believe that all sharks must keep swimming to survive? To move water across their gills to breathe?
The Maritime Aquarium is all about letting you get close to our animals, sharks included. We currently have seven species of sharks on display. When you visit, odds are good that the sharks of only one of the seven species will be swimming.
The sharks of the other six species probably will be … not swimming. Resting on the bottom.
For The Maritime Aquarium’s “Shark & Ray Touch Pool,” we favor species of sharks that are less active, to offer you a better chance of getting a feel for them – literally. The nurse sharks, epaulette sharks, brown-banded bamboo sharks and coral catshark are all species that prefer to hang out on the bottom. This makes it easier for you to run two fingers down their backs – a fun, learning opportunity. (The chain catsharks in an exhibit nearby are similarly inactive.)
The Maritime Aquarium's lemon shark, at rest in the "Ocean Beyond the Sound" exhibit.
Certainly, a number of species of sharks swim pretty much 24/7. Sometimes – like with great whites, makos and whale sharks – they have to swim to breathe. (It’s called obligate ram ventilation.) As they move, water flows into their open mouths and over their gills.
But there other reasons for sharks to just keep swimming, just keep swimming. Sharks – including the big sand tiger sharks that dominate The Maritime Aquarium’s “Ocean Beyond the Sound” exhibit – sink if they stop swimming! And, on very rare occasions, for whatever reason, our sand tigers do. They’ll spend a brief time on the bottom and then resume swimming.
(Why do they sink if they stop swimming? Sharks lack swim bladders. Water moving over their pectoral – or side – fins provides lift in the same way that wings on an airplane provide lift. No water movement, no lift.)
Over the years, we’ve learned that most sharks can alternate between swimming to breathe (ram ventilation) and sucking water into their mouth and over their gills (buccal pumping). Obviously, if you can breathe without swimming, your energy requirements – and thus your need to hunt for food – are lower.
Besides our sand tiger sharks, a 7-foot lemon shark also lives in the “Ocean Beyond the Sound” exhibit. She spends the majority of her time on the bottom.
And the sharks in our “Shark & Ray Touch Pool” are generally at rest too. Being on the bottom works out just fine for these species because that’s where they tend to find their prey: animals that also live on – or bury into – the sea floor. Plus, many of these shark species don’t get very big, so staying low will prevent them from being preyed upon by bigger fish, including larger species of sharks, higher in the water column.
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