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The Explorer's Guide contains a treasure trove of aquatic science resources developed for use in K-12 classrooms. Back to Explorer's Guide.


Cookie Cutter Shark Scientific Name: Isistius brasiliensis
A small, but ferocious shark, the cookie cutter sinks its teeth into prey much larger than itself. This shark appropriately gets its name by biting perfectly circular plugs of flesh from its prey—much like an actual cookie cutter.



Region: Philippines


Taxon: Fish


Appearance
The cookie cutter shark can be 20 inches (50 cm) long. It is one of the smallest sharks and was once called the “cigar shark". Its round, brown body is much darker on the dorsal side or back and gets lighter toward the belly. The cookie cutter has a black collar or band across its throat. The fins are small and close to the body. The largest fin, the caudal fin or tail fin, powers this little shark up from the depths of the ocean.


Habitat
Living in the dark depths of the ocean, the cookie cutter shark can be found to depths of 11,500 feet (3,570 m). At night, the cookie cutter ventures to the surface to feed, but spends its days in the depths.


Range
Cookie cutter sharks live in the depths of all the oceans near the equator where the water is warm.


Diet
Forming a suction cup with its mouth, the cookie cutter shark latches onto its prey. The top teeth are small, pointy and sharp to grasp hold of the prey’s skin. Turning in a circle, this shark carves a round chunk of flesh out with its larger razor-sharp, serrated or saw-like bottom teeth. In a flash, the cookie cutter scoops out the meal. After attacking, its prey is left with an almost perfectly round mark that looks like someone used a round cookie cutter on its body.

Cookie cutters bite chunks out of large billfish like marlins and tunas, large squid, seals, whales, dolphins, other sharks, and stingrays. This shark has even been recorded to take a bite out of a nuclear submarine’s rubber dome.

The entire ventral surface or belly of the cookie cutter shark glows. This glowing area looks like a small fish from below. The cookie cutter shark’s prey swims up to eat what they think is a small fish. Just as the prey is about to chow down, it is surprised and gets bit by the cookie cutter.


Reproduction
Cookie cutter sharks are ovoviviparous. This means they give birth to live pups or baby sharks after the young develop inside egg cases inside the uterus. Egg cases are thin, leathery cases that protect each developing pup. Each developing egg is enclosed within an individual egg case. A developing pup feeds off its egg’s yolk. The pups remain inside the egg cases until fully developed and then hatch out. Soon after, the mother gives birth to the pups. It is unknown how big the pups are or how many the mother has at one time.


Endangered
>A species or group of organisms that is in danger of extinction or disappearing from the face of the earth in the near future if its situation is not improved.

Threatened
A species that can be found throughout its natural range but is declining in number and may become endangered in the absence of special protection efforts.

Vulnerable
A species that is not declining in number but is of special concern because it is sensitive to pressure by particular human activities or natural events.

Stable
A species that is not declining in number and is not sensitive to pressures by human activities or natural events.

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Threats and Management
Because cookie cutter sharks live so deep in the ocean, they are hard for large fishing boats to target. However, many boats fish at night, the same time cookie cutters swim up from the depths to eat. For now their population remains stable, but increased pressure from fishing and a lack of law enforcement could eventually catch up with this shark.

Sharks play a crucial role in reef and ocean ecosystems. They prey on weak and diseased animals. Human choices and human interference cause their numbers to decline. Some countries manage their coastal waters to protect sharks. But others have lax fishing laws, or too few resources to enforce laws that exist. In these places, shark populations suffer.

Sharks also suffer in the popular media, which often portray them as people-eating monsters. In reality, sharks don't attack people very often. When they do, it may be because they've mistaken a person for some other prey. Each year, sharks kill an average of eight people worldwide-yet people kill millions of sharks. More importantly, a decline in shark numbers affects the well-being of the entire reef ecosystem.

Fishing boats search the seas for target animals, like tuna, and discard anything else they accidentally catch-like sharks. The unwanted animals, called by-catch, dry out or suffocate on the deck, or get thrown back into the ocean all but dead. Each year, the worldwide fishing industry discards about a third of its total catch. This waste, or by-catch, not only pollutes the ocean but also creates extra work on fishing boats and ruins nets.

Sharks reproduce slowly, bear few young at a time, have a long gestation period, and many swim great distances to find a mate. That's why it takes years for their populations to rebound after a serious decline from overfishing.

FAO (Food and Agriculture Organization of the United Nations) member countries have been working for about a decade to create a plan of action for the conservation and management of sharks throughout the world. Many participating countries have been successful in their efforts. However, the vast size of the ocean and the lack of law enforcement in many areas maintain poor conservation and management of sharks globally.


Did You Know?
For up to three hours after its death, the cookie cutter shark will emit a glow from its mouth.

Cookie cutter sharks are classified as parasites. Parasites hurt their prey, but don’t kill them—just like the cookie cutter.

This shark has never been known to attack a person—probably because they live in deep areas of the ocean where people can not venture.


References
Web Sites:
NOTE: The following Web sites are not maintained by the John G. Shedd Aquarium and will open in a new browser window.

Fishbase:
http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=877

Ichthyology at the Florida Museum of Natural History – Sharks: http://www.flmnh.ufl.edu/fish/sharks/sharks.htm

Print Publications:
Michael, S.W. 1993. Reef Sharks & Rays of the World. A guide to their identification, behavior, and ecology. Petaluma, California: Sea Challengers. 107p. ISBN# 0-930118-18-9.

Perrine, D. 1997. Mysteries of the Sea. Lincolnwood, Illinois: Publications International, Ltd. 312p. ISBN# 0-7853-2430-5.

Tricas, T.C., Deacon, K., Last, P., McCosker, J.E., Walker, T.I. and Taylor, L. 1997. Sharks & Rays. The Nature Company Guides. McMahons Point, Australia. 288p. ISBN# 0-7835-4940-7.


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Vocabulary Words

By-catch – The part of the fisher's catch which is returned to the sea either because it has no value to them. Fishing boats search the seas for target animals, like tuna, and discard anything else they accidentally catch—like sharks. The unwanted animals, called by-catch, dry out or suffocate on the deck, or get thrown back into the ocean all but dead.


Caudal – Having to do with the end or tail of an animal. The tail fin.


Dorsal – The back of an animal. The large fin on the back of a shark; the fin that sticks out of the water when a shark swims near the surface.


Egg case – A leathery protective container that enables shark eggs to mature until hatching.


Extinction – An organism that has not been present on the face of the earth for over 50 years.


Gestation – The period of development of the young in viviparous animals, from the time of fertilization of the egg until birth.


Ovoviviparous – A form of reproduction in which the young, or in this case pups, develop inside thin leathery egg cases inside the mother. Each pup receives food from a yolk sac inside the egg case. After the pups fully develop, they hatch from their egg cases. Soon after, the mother gives birth to the pups.


Organism – A living thing.


Overfishing – The excessive fishing or catching of aquatic (ocean or freshwater) animals to the point that the amount of animals being caught is greater than the amount of animals born. When more animals are caught than are being born, the aquatic environment is left depleted of the targeted animals.


Pup – A baby shark.


Serrated – The edges of the teeth have small teeth like those on a saw; jagged-edged having saw-like notches along the edge.


Species – A group of organisms capable of breeding and producing fertile offspring; organisms that share the same gene pool.


Ventral Surface – The belly of an animal.


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CONTENTS:

Cookie Cutter Shark
Credit: John G. Shedd Aquarium

Cookie Cutter's Mouth
Copyright Gwen Lowe/Seapics.com

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