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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.


Blacktip Reef Shark Scientific Name: Carcharhinus melanopterus
A small group of blacktip reef sharks often hunt down schools of fish together. They work together to corral the fish into a tight ball, and then attack the trapped prey. This feeding frenzy often results in the blacktips leaping out of the water to catch the prey that are trying to escape.



Region: Philippines


Appearance
With a length up to 6 feet (1.8 m) and weight up to 100 pounds (45 kg) blacktip reef sharks are considered a small to medium-sized shark. This shark is often confused with the larger 9 foot (2.7 m) blacktip shark, which almost always swims in the open ocean away from coral reefs.

The blacktip reef shark is a common reef shark that can easily be identified by its black-tipped fins. Below the black tip on the large first dorsal fin or back fin, there are black splotches followed by a white band. Most of the dorsal part of the body is a light grey-brown which fades to white near the ventral or stomach area. Like most sharks, the blacktip exhibits countershading. This means the shark has a dark-colored back and a light-colored belly. When viewed from below, the blacktip blends in with the brightness of the sunny waters above. Viewed from above, the shark blends in with the dark ocean bottom. Countershading camouflages the animal, allowing it to sneak up on unsuspecting prey.

The blacktip has a short round snout or nose. The teeth are long, thin, and serrated or saw-toothed, which are suited for its diet of reef fish.


Habitat
Blacktip reef sharks live in shallow lagoons and on coral reefs near reef drop-offs. In general, these sharks do not swim deeper than 33 feet (10 m), but can be found as far as 250 feet (75 m) down. These fish also live in mangrove areas, moving in and out with the tide. Blacktip reef sharks even venture into fresh water but don’t swim too far in from the ocean.

These sharks are active swimmers that can most often be found cruising along the bottom. Sometimes blacktip reef sharks can be found swimming at the surface in very shallow waters. They will travel alone or in small groups.

Unlike many sharks that travel vast sections of the ocean, blacktips rarely venture out of a one square mile (2.59 km2) section of a reef.


Range
Blacktip reef sharks live in the warm parts of the Pacific Ocean and Indian Ocean.


Diet
With a sleek body and speedy tail, the blacktip reef shark sneaks up on prey with ease. Cruising coastlines in large schools, blacktip reef sharks often jump out of the water during a feeding frenzy of schools of fish, rays and even small sharks. Blacktips mainly eat reef fish, but also eat squid, octopuses, cuttlefish, shrimp, crabs, and sea snakes.


Reproduction
Of the three different ways that sharks reproduce, blacktip reef shark are live-bearing or viviparous fish. This form of reproduction is very uncommon in fish as most fish lay eggs. This advanced reproductive ability gives us a clue that these sharks are highly developed animals. Sharks don’t have a placenta like mammals, but they do have a uterus. Inside the uterus, each embryo is enclosed inside a separate membrane. The embryos attach to an egg yolk and leach nutrients from the yolk until birth. The babies or pups are born when they are old enough or large enough to survive on their own. Blacktips bear litters of one to four pups or baby sharks. The gestation period lasts at least eight months, but can be as long as 16 months. When born, the pups are 13 to 20 inches (33 to 50 cm) long.


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
Being a smaller shark, the blacktip reef shark falls prey to larger sharks and groupers—large reef fish. But this shark also falls prey to humans. Blacktips are common in shallow waters and live near the shore, making them easy for fishers to hunt. They have been listed as vulnerable because more sharks are being caught than are replaced through reproduction. Like all sharks, blacktips have a very long gestation period and produce few young at a time. This makes it hard to replenish their population quickly.

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.

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?
Blacktip reef sharks must swim constantly with their mouths open, allowing oxygen-rich water to flow over the gills or breathing structures, which are located in five separate slits on each side of the head. Since sharks don’t have a swim bladder like bony fishes, they will sink to the bottom if they stop swimming.

The blacktip reef shark is not considered to be a threat to people, even though they often swim up into the shallow waters where there are many snorkelers and scuba divers.


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

IUCN:
http://www.redlist.org/search/details.php?species=39375

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 that 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.


Countershading – A form of camouflage in which an animal has a dark-colored back and a light-colored belly. Using fish as an example, when viewed from below, a fish blends in with the brightness of the sunny waters above. Viewed from above, the animal blends in with the dark ocean bottom. Countershading camouflages the animal, allowing it to sneak up on unsuspecting prey or hide from predators.


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.


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.


Gills – Structures used for breathing; gills extract oxygen out of water.


Organism – A living thing.


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.


Snout – The pointy part of the head; similar to our nose.


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


Ventral – The belly of an animal.


Viviparous – A form of reproduction in which the young, or in this case pups, develop inside the mother. Each pup receives food from the mother’s blood through an umbilical cord. The pups are born fully developed and able to hunt and swim on their own. This form of reproduction is referred to as “live birth".


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CONTENTS:

Blacktip Reef Shark
Blacktip Reef Shark

Blacktip Reef Shark 2
Blacktip Reef Shark 2

Blacktip shark (Carcharhinus melanopterus) Copyright Shedd, Tom Berault
Blacktip shark (Carcharhinus melanopterus) Copyright Shedd, Tom Berault

Blacktip Reef Shark 4
Blacktip Reef Shark 4

Blacktip Reef Shark 5
Blacktip Reef Shark 5

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