CHAPTER 1
Sharks are a group of fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the
head, and pectoral fins that are not fused
to the head.Modern sharks are classified within the clade Selachimorpha
(or Selachii), and are the
sister group to the rays. However, the term
"shark" has also been used for extinct members of the subclass Elasmobranchii
outside the Selachimorpha, such as Cladoselache and Xenacanthus. Under this broader
definition, the earliest known sharks date from more than 420 million years
ago.
Since that time,
sharks have diversified into over 400 species. They range in size
from the small dwarf
lanternshark (Etmopterus pfish by filter feedingerryi),
a deep sea
species of only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus),
the largest fish in the world, which reaches approximately 12 metres
(39 ft). Despite its size, the whale shark feeds only on plankton, squid, and small. Sharks are found in all seas and are
common down to depths of 2,000 metres (6,600 ft). They breathe through
five to seven gill
slits. Sharks have a covering of dermal denticles that protects their
skin from damage and parasites in addition to improving their fluid
dynamics. They also have several sets of replaceable teeth.
One of we Well-known species such as the great white
shark, tiger shark, blue shark, mako shark, and the hammerhead
shark are apex predators organisms
at the top of their underwater food chain. Their predatory
skill fascinates and frightens humans, even though their survival is threatened
by human-related activities.
The tiger
shark, Galeocerdo cuvier, is a species of requiem shark and the only member of the genus
Galeocerdo. Commonly
known as sea tiger, the tiger shark is a relatively large macropredator,
capable of attaining a length of over 5 m (16 ft). It is found in
many tropical and temperate waters, and is especially common around central Pacific islands. Its name derives from the dark stripes down its body which
resemble a tiger's pattern, which fade as the shark matures.
The
tiger shark is a solitary, mostly nocturnal hunter. Its diet includes a wide
variety of prey, ranging from crustaceans, fish, seals, birds, squid, turtles, and sea snakes to dolphins and even other smaller sharks. The tiger shark is considered a near
threatened species due to finning and fishing by humans.
While
the tiger shark is considered to be one of the sharks most dangerous to humans,
the attack rate is low according to researchers. The tiger is second on the
list of number of recorded attacks on humans, with the great white shark being first. They often visit shallow reefs, harbors and canals,
creating the potential for encounter with humans.he shark was first described
by Peron and Lessueur in 1822, and was given the name Squalus cuvier.Müller and Henle in 1837 renamed it Galeocerdo tigrinus. The genus, Galeocerdo,
is derived from the Greek galeos which means shark and the Latin cerdus
which means the hard hairs of pigs. It is often colloquially called the
man-eater shark.
Scientific Clasification
Species : G. Cuvier
CHAPTER
II
2.1 Description Charakter unique
of the komodo
Figure 1
The
tiger shark is characterized among the Atlantic members of its family by the
forward position of its first dorsal fin (origin about over the arm pit of the
pectorals), combined with a caudal peduncle with a low longitudinal ridge of
skin on either side, besides a well-marked semilunar pit below as well as
above; a very small second dorsal fin; a furrow, about as long as the snout
along either side of the upper jaw; a very slender tipped caudal fin with
moderately large and pointed lower lobe; and large teeth alike in the two jaws,
of very characteristic shape, with convex inner margins, deeply and
conspicuously notched outer margins and strongly serrate edges (fig. 1).Young
tiger sharks are rather slender, but they become very heavy forward, with
growth, though they continue tapering toward the tail. The first dorsal fin is
high, triangular, and nearly as large as the pectorals, while the second dorsal
is hardly one-third to one-fourth as high as the first and stands over the
anal, which is of about equal size. The lower tail lobe is almost half as long
as the upper, the rear margin of which is notched near the tip. The large size
of the head, with very short, obtusely rounded front outline, and broad mouth
occupying nearly four-fifths of the width of the head, with long grooves along
the upper jaw, combined with the unique shape of its teeth, make the
"tiger" easy to recognize among Gulf of Maine sharks.The colour of
this shark is Gray, or grayish brown, darkest on the upper surface. Young
"tigers" up to 5 or 6 feet long, are more or less conspicuously
spotted or barred with darker brown on the back and along the upper parts of
the sides. But these markings fade with advancing age until large specimens are
plain colored, or nearly so.
Tiger
sharks are small at birth, corresponding to the large numbers in a litter, free
living specimens having been reported only 18 to 19 inches long. By the time
they mature they are among the larger sharks; but their size has often been
overestimated. The majority of tigers caught in centers of abundance are less
than 12 to 13 feet long, and the largest measured lately in the western
Atlantic was one of about 18 feet, from Cuba. Repeated statements that the
tiger grows to a maximum length of 30 feet have no reliable foundation, so far
as we can discover.
2.2 Habitat of the tiger shark
This
voracious shark, with wide jaws and powerful teeth, preys upon the large sea
turtles, other sharks, fish, and occasionally on invertebrates such as
horseshoe crabs, crabs, conchs, whelks. It is proverbial for its habit of
feeding on slaughter-house wastes or any other carrion. Remnants of squeteague,
mackerel, hake, scup, menhaden, goosefish, and dogfish all have been found in
stomachs of tiger sharks taken at Woods Hole. there is no placental connection
between mother and young, and the broods are very large, as many as 82 having
been counted in a large female; but other litters as small as 10 to 14. In the
West Indies it is much dreaded, whether or not with good cause.
The tiger
shark is often found close to the coast, mainly in tropical and subtropical waters
throughout the world. Along with the great white shark, Pacific sleeper shark, Greenland shark and sixgill shark, the tiger shark is among the
largest extant sharks. Its behavior is primarily nomadic, but is
guided by warmer currents, and it stays closer to the equator throughout the
colder months. It tends to stay in deep waters that line reefs, but it does
move into channels to pursue prey in shallower waters.
In the western Pacific Ocean, the shark
has been found as far north as Japan and as far south as New Zealand. A Tiger
Shark tagged in the Caribbean has been
tracked migrating Cape Cod, although
Tiger Sharks are a tropical species during the summer the warm Gulf Stream brings the
coast of Cape Cod to within the extreme north of its range.
Tiger sharks can be seen in the Gulf of Mexico, North American beaches and parts of South America. It is also commonly known in the Caribbean Sea. Other locations where tiger sharks
are seen include Africa, People's Republic of China, Hong Kong, India, Australia and New Zealand.
Certain tiger sharks have been recorded at depths just
shy of 900 metres (3,000 ft) but some sources claim they move into shallow
water normally thought to be too shallow for a species of its size.A recent
study showed the average tiger shark would be recorded at 350 metres
(1,100 ft), making it uncommon to see tiger sharks in shallow water. However,
tiger sharks in Hawaii have been observed in depths as shallow as 10 ft
and regularly observed in coastal waters at depths of 20 to 40 ft. They
often visit shallow reefs, harbors and canals, creating the potential for
encounters with humans.
Tiger shark is known as tababa in Kiribati and Tuvaluan. They have
been observed feeding in the tidal passages between the lagoon and ocean in Tarawa, Kiribati. Spring tides bring in plankton or animalcule, which
attract small soft-shell crabs, which attract sardines, which
attract the grey mullet, which
attract the blue-backed trevally (rereba),
which then attract the tiger shark (tababa).
2.3 Feed of
the tiger shark
The tiger shark is an apex predator and has a
reputation for eating anything. It also possesses the capability to take on
large prey. It commonly preys upon fish, crustaceans, mollusks, jellyfishes, dugongs, seabirds, seasnakes, marine mammals (e.g. bottlenose dolphins, spotted dolphins]), and sea turtles (e.g. green and loggerhead turtles). The broad, heavily calcified jaws
and nearly terminal mouth, combined with robust, serrated teeth, enable the
tiger shark to take on these large prey. In addition, excellent eyesight and acute sense of smell enable it
to react to faint traces of blood and follow them to the source. Due to high
risk of predatory attacks, dolphins often avoid regions inhabited by tiger
sharks. The tiger shark also eats other sharks (such as sandbar sharks) and
will even eat conspecifics.
Tiger sharks may also attack injured or ailing whales and prey
upon them. A group was documented attacking and killing an ailing humpback whale in 2006 near Hawaii. The tiger shark also scavenges on
dead whales. In one such documented incident, they were observed scavenging on
a whale carcass alongside great white sharks, Carcharodon carcharias.
The ability to pick up low-frequency pressure waves
enables the shark to advance towards an animal with confidence, even in murky
water. The shark circles its prey and
studies it by prodding it with its snout. When attacking, the shark often eats
its prey whole. Because of its aggressive feeding, it often mistakenly eats
inedible objects, such as automobile license plates, oil cans, tires, and baseballs. For this reason, the tiger shark
is often regarded as the ocean's garbage can.
2.4 Reproduction
Males reach sexual maturity at 2.3 to
2.9 m (7.5 to 9.5 ft) and females at 2.5 to 3.5 m (8.2 to 11 ft). Females mate
once every 3 years. They breed by internal fertilization. The male inserts one
of his claspers into the female's genital
opening (cloaca), acting as a guide for the sperm. The male uses its teeth to hold the
female still during the procedure, often causing the female considerable
discomfort. Mating in the Northern Hemisphere generally takes place between
March and May, with birth between April and June the following year. In the
Southern Hemisphere, mating takes place in November, December, or early
January. The tiger shark is the only species in its family that is ovoviviparous; its eggs hatch internally
and the young are born live when fully developed.
The young develop inside the mother's
body for up to 16 months. Litters range from 10 to 80 pups. A newborn is
generally 51 centimetres (20 in) to 76 centimetres (30 in) long. This
shark typically reaches maturity at lengths of 2 to 3 m (6.6
to 9.8 ft). It is unknown how long tiger sharks live, but they can live longer
than 12 years.
2.5 Danger and conversation
Although shark attacks are a
relatively rare phenomenon, the tiger shark is responsible for a large
percentage of fatal attacks and is regarded as one of the most dangerous shark
species. They are often found in river estuaries and harbors, as well as
shallow water close to shore, where they are likely to encounter humans. The
tiger shark also dwells in river mouths and other runoff-rich water. On average,
three to four shark attacks occur per year in Hawaii, and most attacks are not
fatal. This attack rate is surprisingly low considering thousands of people
swim, surf and dive in Hawaiian waters every day. A tiger shark attack made
headlines in October, 2003, when (then 13-year-old) American surfer Bethany Hamilton lost her arm near her shoulder. A
large tiger shark was killed and hung, and later measured; based on its size
and bite pattern, it was presumed to be the shark which attacked Hamilton.
Between 1959 and 1976, 4,668 tiger sharks were culled in an
effort to protect the tourism industry.
Despite these efforts, attacks did not decrease. It is illegal to feed sharks
in Hawaii, and interaction with them, such as cage diving, is
discouraged. South African shark behavioralist
and shark diver, Mark Addison, demonstrated divers could interact and dive with
them outside of a shark cage in 2007 Discovery Channel special.
The tiger shark is captured and killed for its fins, flesh, and liver. It is caught regularly in target
and nontarget fisheries. Several populations evidently have declined where they
have been heavily fished, but in general, they do not face a high risk of
extinction. Continued demand, though, especially for fins, may result in
further declines in the future. Tiger sharks are considered a near threatened species due to excessive finning and fishing by humans according to International
Union for Conservation of Nature.
While shark fin has very few nutrients, shark liver
has a high concentration of vitamin A which is
used in the production of vitamin oils. In addition, the tiger shark is
captured and killed for its distinct skin, as well as by big game fishers.
In 2010, Greenpeace International added the tiger
shark to its seafood red list, which is a list of fish commonly sold around the
world, and which have a very high risk of being sourced from unsustainable
fisheries.
CHAPTER
III
3.1
Conclution
The tiger shark is
characterized among the Atlantic members of its family by the forward position
of its first dorsal fin (origin about over the arm pit of the pectorals),
combined with a caudal peduncle with a low longitudinal ridge of skin on either
side, besides a well-marked semilunar pit below as well as above; a very small
second dorsal fin; a furrow, about as long as the snout along either side of
the upper jaw; a very slender tipped caudal fin with moderately large and
pointed lower lobe; and large teeth alike in the two jaws, of very
characteristic shape, with convex inner margins, deeply and conspicuously notched
outer margins and strongly serrate edges. The tiger
shark is often found close to the coast, mainly in tropical and subtropical waters
throughout the world. The tiger
shark is an apex predator and has a
reputation for eating anything.
It also possesses the capability to take on
large prey. It commonly preys upon fish, crustaceans, mollusks, jellyfishes, dugongs, seabirds, seasnakes, marine mammals (e.g. bottlenose dolphins, spotted dolphins]), and sea turtles (e.g. green and loggerhead turtles). .
They breed by internal fertilization. Although shark attacks are a
relatively rare phenomenon, the tiger shark is responsible for a large
percentage of fatal attacks and is regarded as one of the most dangerous shark
species.
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