Who’s Eating Whom?
Millions of years ago, long before there was a Chesapeake, sharks thrived in the saltwater marine environment of the flooded river we now call Susquehanna. Big sharks that could have swallowed a man whole, had any men or women been around to be eaten.
The megalodon, ancestor of the great white shark, was the apex marine predator of those waters. Rivaling today’s blue whale, the megalodon grew up to 50 feet long.
He’s long gone, but his kin are still with us.
Perhaps a dozen kinds of sharks visit our Chesapeake. Atlantic mako sharks, sand and sandbar or brown sharks, hammerheads, bonnetheads, dusky, sharp-nosed, smooth and spiny dogfish sharks, chain catsharks. And bull sharks.
1. Sharks are highly adaptable and now live in every ocean in the world in warm, temperate and cold waters.
2. Sharks have existed for 400 million years, since before the dinosaurs, with little evolution.
3. A shark can smell blood in the water from up to three miles away.
4. The largest shark of all, the whale shark, can live upwards of 100 years. Some smaller sharks live 20 to 30 years.
5. Due to low cancer rates among sharks, their cartilage is being studied for a possible cure.
6. The Swell Shark, found in New Zealand, makes a dog-like bark.
7. Native Hawaiians believe deceased relatives are reincarnated as sharks, so it is an offense to harm one.
8. The first description written of a shark was by Herodotus, who in the fifth century bc wrote of “monsters” eating shipwrecked Persians.
9. The word shark first appeared in 1569. Earlier English mariners used the term sea dog.
“Bull sharks are one of the notorious sharks we need to watch out for,” says David Moyer, curator of estuarine biology at Calvert Marine Museum. “They’re the inspiration species for Jaws. They come all the way up into fresh water. That story came out of a whole lot of real-life shark attacks over a short period of time in fresh waters in New Jersey.”
It was an eight-foot bull shark that Solomons waterman Willy Dean caught in the lower Potomac River two years ago. “I never caught anything like that before,” Dean told Bay Weekly.
Twenty million years ago, the Miocene Atlantic Ocean sprawled all the way to the modern times marker of old Highway 1. Calvert Marine Museum, Annapolis, Baltimore — all would have been covered by 200 feet of water. In that warm salty bath, a menagerie of marine creatures lived and died.
“For millions of years, hundreds of different species lived in that shallow marine environment,” says Stephen Godfrey, Calvert Marine Museum’s curator of paleontology. Their remains we find entombed in this giant layer of sediment exposed along the Calvert Cliffs.
Biggest of them all was the megalodon, though the company of sharks was swelled by gray sharks, huge mako sharks, sand tigers, hammerheads, snaggletooths, cow sharks and thrashers, all relatives of earth’s current roster of some 440 kinds of sharks, which range from the six-inch-long dwarf shark to the 20-foot-long great white.
Big as boxcars, megalodons would have feasted on all those sharks, plus seals, sea cows, swordfish, crocodiles and tuna. “Tastiest of all,” Godfrey says, would have been “early baleen whales with their big muscular tongues and lots of blubber.”
All that remains of those sharks are the teeth, from the size of rose thorns to as big as a man’s hand. Their cartilage skeleton decayed millions of years ago, but teeth remain by the millions, indeed billions, to tell their story. From them, and from the other fossils in the extraordinarily rich and exposed Cliffs, the past of millions of years ago has been reconstructed.
“The Cliffs are an easily accessible portal to that block of earth history,” says Godfrey.
Calvert Marine Museum in Solomons is shark central in our part of the Chesapeake. Sharks R Us the museum could advertise, and one day every year Sharkfest gives the creatures and their history and lore, center stage. That day’s coming up on Saturday, July 14.
“Sharks are like the dinosaurs of the ocean world,” says Museum deputy director Sherrod Sturrock. “People come out of the woodwork to learn about them. Sharkfest is huge.”
The stars of Sharkfest are the real thing.
Five chain dogfish, all between 10 and 12 inches, now make their home at Calvert Marine Museum. Their better name, says their keeper Moyer, “is chain catsharks, for their eyes have slit-like pupils like a cat’s.”
That adaptation may be because they live in deep waters that do not receive natural sunlight. They also luminesce, perhaps for the same reason, or perhaps to attract food or their own kind or to discourage predation.
When you visit, it won’t be dark enough for you to see them glow. But as they swim in their cool, salty tanks, you’ll see what Moyer calls their “charismatic” good looks, the chainlike mottled markings that give them the other half of their name.
The chain catsharks join their cousins, clearnose skates and cownose rays, in filling out the museum’s shark family. Like the catsharks, rays are regular visitors throughout the Chesapeake. Skates, which prefer the saltier water of the lower Bay, are a specialty of the museum, which breeds the flat fish to share with other museums and aquariums.
Also visiting are another shark cousin and Chesapeake Bay native, the Atlantic sturgeon, an endangered species being bred by GenOn Aquaculture in Virginia for reintroduction to the upper Potomac River.
The scariest shark at Sharkfest is the full-sized megalodon, a 50-foot-long behemoth model created at the museum 15 years ago to put the past in chilling perspective.
Sharks are an awe-inspiring species. It’s not only their efficient union of form and function that we admire; we also stand in awe of a predator that, in its larger sizes, preys on us.
More often, however, it’s the other way around.
Between 1580 and 2011, 2,463 unprovoked shark attacks have been confirmed. Of the 980 unprovoked attacks in the U.S., only 36 have been fatal.
Being killed by a shark is 30 times less likely than being killed by falling airplane parts.
Humans are far more efficient predators, killing about 100 million sharks a year — 11,000 each hour.
This keystone species is vilified, ruthlessly hunted and now threatened. Commercial fishing accounts for much of the loss. Bycatching — getting caught by fishermen seeking other prey — and habitat degradation — owing to global warming, pollution and the destruction of mangroves and reefs — also contribute to the total.
The World Conservation Union lists 201 sharks on its endangered list. A third of all sharks are at serious risk of extinction. Some species, including the scalloped hammerhead, have declined by 98 percent.
Preserving these ancient animals is critical to the health of our oceans. Sharks are a key indicator species for environmental health. “If you don’t find sharks in an expected range, it’s a good indication the ecosystem is challenged by overfishing or pollution,” says Moyer.
Preservation starts at home. What we do to the waters of Chesapeake Bay trickles into neighboring oceans, even to the great ocean depths where the chain dogfish shark makes its residence off the coast of Maryland.
Sharkfest: Saturday July 14
Avoid the bite of the megalodon or pose in front of its fossilized jaws. Study fossils from the Calvert Cliffs and bring your own beachcombing treasures for experts to identify. Find a 20-million-year-old shark’s tooth in the Discovery Room. Stop by SharkFact stations throughout the museum for tidbits on lives and habitats. See just how powerful a shark is at the Shark Frenzy Film Fest. Step into the Shark Cage that underwater photographers use to capture sharks in their habitat. Pose for a picture in the cage and see the photos taken from it. Kids also model fish-face paint, create shark crafts and examine the shark mural. 10am-5pm at Calvert Marine Museum, Solomons. $7 admission w/discounts: 410-326-2042 x41; www.calvertmarinemuseum.com.