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Sharks In Your National Marine Sanctuaries

Sharks have been around for a long, long time – they evolved before the dinosaurs did, and their time on Earth even predates trees! Over these hundreds of millions of years, they’ve adapted key features that enable them to thrive in a variety of habitats.

WHALE SHARK
These gentle giants are the largest shark in the sea. Despite their large size, whale sharks prefer tiny food, filtering plankton out from the water column.

GREAT HAMMERHEAD
Hammerheads’ odd head shape is called a cephalofoil. This broad head helps the shark see in nearly 360 degrees, and detect prey using electrical fields.

NURSE SHARK
The nurse shark just might win the award for laziest shark. These small sharks like to hang out in the seafloor, where they dine on small invertebrates and fish.

WHITE SHARK
Each year, adult and juvenile white sharks migrate to Greater Farallones National Marine Sanctuary to feed on abundant northern elephant seals and sea lions.

SAND TIGER SHARK
These large sharks may be toothy, but they’re actually quite docile. Sand tiger sharks are common visitors to shipwrecks around the sanctuary system.

Papahānaumokuākea
TIGER SHARK – oceanic & shallow coastal waters
Hawaiian Islands Humpback Whale
GALAPAGOS SHARK – near reefs, seamounts, & islands
American Samoa
BLACKTIP REEF SHARK – coral reefs
Olympic Coast
PACIFIC SPINY DOGFISH – intertidal zone to continental shelf
Greater Farallones
WHITE SHARK – coastal & open ocean
Cordell Bank
THRESHER SHARK – open ocean
Channel Islands
BLUNTNOSE SIXGILL SHARK – deep sea
Thunder Bay
IMPOSTER SHARK – land
Stellwagen Bank
BASKING SHARK – coastal & open ocean
Monitor
SAND TIGER SHARK – coastal waters, shipwrecks
Gray’s Reef
NURSE SHARK – reefs, seagrass flats, mangrove islands
Florida Keys
GREAT HAMMERHEAD – coral reefs, coastal waters
Flower Garden Banks
WHALE SHARK – open ocean

Fun Facts

Dorsal Fin
When many people think of sharks, the first thing they picture is a dorsal fin cutting through the ocean surface. Dorsal fins are key to sharks’ success, helping stabilize them in the water so they can move quickly and make sharp turns.

Electrical Sensors
Sharks have a sixth sense! Special organs called ampullae of Lorenzini enable sharks to sense electrical fields. This sense can help sharks locate their prey even if it’s buried in the sand or in murky water. Hammerheads have an especially large number of ampullae.

Filter Feeders
Not all sharks go for big prey – whale sharks and basking sharks are filter feeders. They suction water into their mouths, where filtering pads separate plankton from the water.

Whale sharks can weigh up to 40,000 pounds (20 tons). That’s roughly the size of three African elephants.

Coloration
Many sharks, including white sharks, are dark on the top of their body and white on the bottom. This countershading helps them hide from prey, blending in with well-lit water above or darker water below.

Skeleton
Unlike other fish, sharks don’t have bony skeletons. Instead, their skeletons are made up of cartilage, the same flexible tissue that makes up your ears and nose tip. Cartilage is lighter than bone, helping sharks stay buoyant.

Skin
Most sharks have rough skin that feels like sandpaper. Their skin is made up of tiny teeth-like scales, which point toward the tail and help reduce friction in the water.

Sense of Smell
Sharks have a keen sense of smell that helps them detect prey from far away. White sharks are thought to have the largest olfactory bulb of any shark.

Apex Predator
Some sharks, like white sharks, are what’s known as an apex predator: they occupy the top of the food web.

Power
White sharks use their powerful tails to generate impressive speed. While hunting, white sharks are even known to breach and completely clear the ocean surface.

Barbels
Nurse sharks have whisker-like appendages on their lips called barbels, which help them sense prey along the ocean floor.

Gulps Air
Sand tiger sharks lack the swim bladder that most bony fish use to control their buoyancy. Instead, they come to the surface and gulp air into their stomach, which allows them to hover in the water column.

Shark Cousins
Skates and rays are closely related to sharks. All three are elasmobranchs, a kind of cartilaginous fish.

Evolution

Sharks are one of the oldest kinds of animals in the ocean. They evolved more than 425 million years ago – long, long before mammals like whales roamed the seas.

Specific timescale:

Corals: 500 million years ago to present
Sharks: 425 million years ago to present
Dinosaurs: 240-66 million years ago
Whales: 35 million years ago to present
Modern humans: 2 million years ago to present

Teeth

Humans go through two sets of teeth in our lifetime, but sharks may go through thousands! Many sharks have multiple rows of razor-sharp teeth. As they shed teeth, new ones move forward to replace them.

Whale Shark
Hundreds of rows of tiny hooked teeth line the whale shark’s mouth, but are thought to have no role in feeding.

Nurse Shark
Small serrated teeth and strong jaws enable nurse sharks to crush hard-shelled invertebrates

Great Hammerhead
Strong serrations help great hammerhead sharks chomp down on bony fishes, stingrays, and other marine organisms.

White Shark
White sharks have the quintessential triangular, serrated shark teeth. Some 300 teeth enable them to grab large prey like seals and sea lions.

Sand Tiger Shark
Ragged-looking teeth make sand tiger sharks look quite hostile, but generally speaking, these sharks are docile around humans.