Japanese Wobbegong Shark
Scientific Name: Orectolobus japonicus
Sporting splotchy skin, the Japanese wobbegong shark blends in with the reef corals, rocks and sand. Lying on the ocean bottom, this shark goes unnoticed by it prey. As an unsuspecting fish swims on by, the Japanese wobbegong jumps up and gulps down the creature before it can escape.
The Japanese wobbegong shark looks like a combination of a shark and a ray, with a slightly flattened body and a very large head. This wobbegongs mouth is quite large with very distinctive barbels or flaps of skin used in tasting and feeling that hang from its mouth. The teeth are long, thin and dagger-like with the bigger teeth in the center of the mouth and smaller ones toward the ends. This creature can be up to 3 feet (1 m) long. Covered with splotches of brown, beige and white, the skin of Japanese wobbegong helps this shark to blend in with the coral covered reef and the rocky and sandy ocean bottom.
Japanese wobbegong sharks live on coral and rocky reefs in the channels or on sand flats to depths of 40 m (130 feet). This fish rests under tabletop corals, among ship wreckage, in caves, or beneath ledges during the day.
Japanese wobbegong sharks live in the warm parts of the Pacific Ocean.
The diet of the Japanese wobbegong consists almost entirely of fish, but this shark will occasionally eat shrimp, crabs, octopuses, cuttlefish and snails. The wobbegong mainly hunts at night, but will also ambush animals while resting during the day.
Lying hidden among the corals or sand, this wobbegong startles unsuspecting prey by jumping out at them when they venture near. Before the prey can even realize it, they are in the grasp of the wobbegongs sharp teeth. The Japanese wobbegong keeps hold its prey until they animal calms down. The shark then flips the animal around so it can swallow it head first. Most fish have sharp spines within their fins. By swallowing a fish head first, the fish cant stick out a fin and get stuck inside the sharks throat.
The flattened head of the Japanese wobbegong shark makes it easy to dive into reef cracks and crevices where prey animals try to escape to and hide.
This shark is ovoviviparous, meaning their eggs remain protected inside egg cases inside the uterus. A thin, leathery egg case contains each wobbegong egg, which feeds off the yolk as it develops into a pup or baby shark. The pups remain inside the egg cases until fully developed and then hatch out. Soon after, the mother gives birth to the pups. The Japanese wobbegong shark gives birth to 1 to 27 pups, which are about 8 inches (20 cm) long. The gestation period is about 1 year.
Young wobbegongs hide in deep reef holes, caves and crevices until they are large enough to fend for themselves. They can even be found living under rocks and in tidepools or shoreline areas that experience times of flooding and dryness.
>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.
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.
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.
A species that is not declining in number and is not sensitive to pressures by human activities or natural
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Threats and Management
Japanese wobbegong shark are hunted, but they are currently not being overfished. Camouflaged against the reef, this shark is hard for fishers to spot. Their coloration may be saving them from declining in numbers.
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 worldwideyet 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 catchlike sharks. The unwanted animals, called by-catch, dry out and 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.
NOTE: The following Web sites are not maintained by the John G. Shedd Aquarium and will open in a new browser window.
Ichthyology at the Florida Museum of Natural History - Sharks: http://www.flmnh.ufl.edu/fish/sharks/sharks.htm
Michael, S.W. 1993. Reef Sharks & Rays of the World. A guide to their identification, behavior, and ecology. Petaluma, California: Sea Challengers. 107p.
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.
Barbels Flaps of skin near the mouth used in tasting and feeling.
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 catchlike sharks. The unwanted animals, called by-catch, dry out or suffocate on the deck, or get thrown back into the ocean all but dead.
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.
Gills Structures used for breathing; gills extract oxygen out of water.
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.
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.
Pup A baby shark.
Species A group of organisms capable of breeding and producing fertile offspring; organisms that share the same gene pool.
Tidepool The water left in a depression or pool when the tide goes out. The shoreline area that experience times of flooding and dryness due to a change in the tide. Animals common to tidepools are urchins, sea stars and small fish. There is also an abundance of seaweed, seagrass and algae.
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