Outdoors

Sharks of many shapes swim in world’s oceans

Bluntnose sixgill sharks can be found swimming in the depths of Puget Sound.
Bluntnose sixgill sharks can be found swimming in the depths of Puget Sound. Courtesy

Summer always seems to spark a big interest in sharks. These ancient fish, with skeletons made of the same stuff as our ears and nose tips, take over our imaginations.

During this excitement, great white sharks get the most attention. These toothy television stars are the largest carnivorous sharks in the sea. Their jaws are lined with jagged, triangular teeth that are serrated, like a mouth filled with steak knives.

Great white sharks can grow to be 23 feet long, about the length of four refrigerators laid on their backs and lined up end-to-end. A great white can easily hunt whatever it wants, including fish, seals, sea lions, sea turtles, dolphins and more.

Great whites are apex ocean predators, which means that nothing hunts them except humans and other large sharks.

But the great white is only one member of the diverse shark family. More than 400 kinds of sharks swim the world’s oceans. Here are four other species:

ENTER THE GOBLIN

An odd-looking and rarely seen shark lurks in deep ocean waters, from more than 300 to several thousand feet down. Meet the goblin shark.

This well-named fish won’t win any beauty contests. It has a soft, flabby pink and white body, thanks to semi-see-through skin that shows the flush of its blood vessels. A long, flat snout sticks forward like the front of a surfboard over the shark’s snaggly mouth.

Goblin sharks share an ability with hammerheads and many other sharks. They have sensors called ampullae of Lorenzini along that surfboard nose that can detect the natural electrical fields of other animals. This helps them find mollusks, rays and other prey that hide beneath the sandy bottom.

Once a possible meal is close, the goblin shark’s jaws shoot forward out of its mouth. Skinny teeth skewer the prey like a roasted marshmallow on a stick, which is then suctioned back into the goblin shark’s mouth.

Goblin sharks can grow up to 12.5 feet long.

SOCIAL SIXGILLS

Puget Sound is home to another deep-water shark. The bluntnose sixgill has been seen in shallow waters, but is comfortable hanging out 6,500 feet down. Sixgills have six gill slits, while most kinds of sharks have only five.

These sharks are big bruisers like their great white relatives, growing to nearly 16 feet long. Sixgills have wide, rounded heads and move slowly, most likely catching their prey by surprise. They eat flounder, rays, cod and other big fish, even other sharks. Sixgills also scavenge, sawing chunks of flesh from dead whales and seals that have sunk to the sea floor.

A local research team — based at Seattle Aquarium with support from NOAA, University of Washington, state Department of Fish and Wildlife and Point Defiance Zoo & Aquarium — is studying the sixgill shark. Using satellite tags and special marks on the sharks’ bodies, researchers can tell the sharks apart and follow their movements in the Sound.

One finding is that sixgills like to travel in small groups of their brothers and sisters. And they tend to have a lot of those. Sixgill moms give birth to 20 to 100 pups at a time.

COOKIES THAT BITE

Some of the largest animals in the Atlantic and Pacific oceans occasionally come across a nightmare in the form of a shark no bigger than a wiener dog. Less than 2 feet long, the cookie cutter shark appears harmless enough from above. It has big green eyes and a chocolate-colored body shaped like a hot dog. Viewed from below, the cookie cutter shows off a spotty pattern of glowing green light on its underside. Biologists think that the light pattern may make the cookie cutter look like an even smaller fish.

When predators swim toward the tempting little meal, the meal turns and bites them. Cookie cutter sharks have a thick mouth that latches onto a bigger animal like a suction cup. Its curved bottom row of teeth is solid like the edge of a saw blade. The little shark digs into the big prey using this mouth saw.

With a twisting motion, it can pop away and swim off eating a cookie-shaped chunk of flesh. The confused, bigger animal is left with an empty stomach and a deep, round wound in its hide. And, cookie cutters are not picky eaters either. Scientists have found cookie-cutter scars on stingrays, tuna, whales, great white sharks and the rubber parts of at least one submarine.

SPOTTED BEAUTIES

Not all small sharks are so quick to bite. The epaulette is a spotted shark found in coral reefs off the coast of Australia and is considered harmless to people.

Epaulettes belong to a family of carpet sharks that like to swim and “walk” along the bottom using flexible fins shaped like paddles. They have large, black spots ringed with white on their sides above the paddle fins. They hang out in tide pools and other shallow areas, sniffing about for worms, crustaceans and other boneless snacks.

Dinnertime doesn’t end when the tide goes out. Epaulette sharks are specially adapted to power down their bodies and parts of their brains so they need less oxygen. This ability lets them walk across the reef out of the water, continuing to search for food until the tide rises to swimming level again.

Back under the sea, trouble can find our skilled reef hunters. At less than 31/2 feet long, epaulettes can become an easy meal for larger sharks. To help them watch for danger, their eyes are located closer to the tops of their heads, much like stingrays, flounder and other fish that rest on the sea floor. And, the epaulette’s spotted pattern also may break up its body outline, helping it to hide.

MORE ABOUT SHARKS

▪ About one-quarter of all kinds of sharks and rays are now threatened, meaning they are in danger of dying out completely. Some of them are caught accidentally in large fishing nets and hook-lines meant to catch other fish. Some fishermen also kill sharks to sell their fins for making soup.

▪ You can help protect these awesome animals.

▪ Avoid ordering shark fin soup or any shark dish at restaurants. Don’t buy other shark products, such as shark jaws.

▪ Eat seafood that is caught in safer ways. Learn more at seafoodwatch.org.

▪ Experience sharks up close at Point Defiance Zoo & Aquarium. Touch epaulette and whitespotted bamboo sharks. See five species of tropical sharks and watch special shark feeds every Tuesday and Saturday.

▪ Learn more about sharks, the challenges they face in the wild, and how you can help at pdza.org/savesharks.

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