sharks

sharks - Transcript

Sharks
By: Mrs. Meredith Sanders
Great White Shark Information
TEETH TO SPARE
If great white sharks had tooth fairies, they’d be rich! A great white
loses and replaces thousands of its teeth during its lifetime. Its
upper jaw is lined with 26 front-row teeth; its lower jaw has 24.
Behind these razor-sharp points are many rows of replacement
teeth. The “spares” move to the front whenever the shark loses a
tooth. At any one time about one-third of a shark’s teeth are in the
replacement stage.
HEADS UP
Great whites are the only sharks that can hold their heads up out
of the water. This ability allows them to look for potential prey at
the surface. Great white sharks usually attack from underneath,
surprising their unwary prey
Great white sharks are superstars. Before the Star Wars series, the
1975 movie Jaws was Hollywood’s biggest moneymaker. Jaws,
about a great white on the prowl, cost $8 million to film but made
$260 million in the U.S. Not bad for a fish story!
Great white sharks can sprint through the water at speeds of 43
miles an hour (69 kilometers an hour). That’s about 8.5 times as fast
as the top Olympic swimmer. Scientists on the California coast
tracked one shark as it swam all the way to Hawaii—2,400 miles
(3,862 kilometers)—in only 40 days!
BOX OFFICE BULLY & SPEEDY SWIMMERS
Great white sharks can sprint through the water at speeds of 43 miles
an hour (69 kilometers an hour). That’s about 8.5 times as fast as the
top Olympic swimmer. Scientists on the California coast tracked one
shark as it swam all the way to Hawaii—2,400 miles (3,862
kilometers)—in only 40 days!
Unlike most fish, great white sharks’ bodies are warmer than their
surroundings. The sharks’ bodies can be as much as 27.3°F
(15.17°C) warmer than the water the fish swim in. A higher
temperature helps the great white shark swim faster and digest its
food more efficiently. Very useful for an animal that’s always on the
go!
SPEEDY SWIMMERS & HOT ON THE TRAIL
A pregnant female great white shark can carry as many as 14
babies in her belly. At birth, a 5-foot-long (1.52-meter), 60-
pound (22-kilogram) pup looks and acts like a miniature adult.
Great whites average between 10 and 15 feet (3 and 4.6
meters) long. Females tend to be bigger than males. The
longest confirmed great white shark measured 19.5 feet (5.9
meters). Male or female, they’re the world’s largest meat-eating
fish.
A great white shark isn’t all white. A pale belly and dark
charcoal-gray back help the shark avoid detection by prey.
Viewed from above, the shark’s dark-colored back blends with
the murky seafloor. From below, the shark’s belly matches the
light-colored surface. Sneaky!
BIG MAMA & SNEAK ATTACK
“Man-eaters?” Maybe not. Some scientists believe that great white
sharks are better described as “man-biters.” In more than half of all
known great white attacks on swimmers, sharks have taken only a
single bite before swimming away. Scientists speculate that
perhaps people just don’t taste as good as seals or sea lions!

NOT ON THE REGULAR
MENU
Confirmed Unprovoked Shark Attacks
• Florida – 520
• Hawaii – 104
• California – 89
• South Carolina – 52
• North Carolina – 30
• Texas – 32
• Oregon – 18
• Mississippi – 1
• Total in USA from
1670-2005: 902
What is a Shark?
• Sharks are amazing fish that have been around
since long before the dinosaurs existed. They live
in waters all over the world, in every ocean, and
even in some rivers and lakes.
Unlike bony fish, sharks have no bones; their
skeleton is made of cartilage, which is a tough,
fibrous substance, not nearly as hard as bone.
Sharks also have no swim bladder (unlike bony
fish).
The Biggest Shark
The biggest shark is the whale shark (Rhincodon or
Rhiniodon typus), which can be up to 50 feet (15 m) long.
It is a filter feeder and sieves enormous amounts of
plankton to eat through its gills as it swims. It is also the
biggest fish. The second biggest fish and shark is the
basking shark (Cetorhinus maximus) which is about 40
feet (12.3 m) long and is another filter feeder.
The biggest meat-eating sharks are the Greenland shark
and the Great white shark (Carcharodon carcharias)
which grow to be up to 21 feet (6.4 m) long. Great whites
up to 37 feet (11.3 m) long have been reported, but not
verified.
SCARIEST SHARK EVER (NOW
EXTINCT)
The largest shark known was the Megalodon (
Carcharodon or Carcharocles megalodon); it is
now extinct. It was an ancient, meat-eating shark
that lived between 25 million and 1.6 million
years ago. It was up to 40 feet (12 m) long and its
teeth were each the size of a person's hand!
Smallest Sharks
• Dwarf Lanternfish (Etmopterus perryi), which is about 7
1/2 to 8 inches (19 - 20 cm) long for fully-grown females
and 6 to 7 inches (16 - 17.5 cm) long for adult males
• Spined pygmy shark (Squaliolus laticaudus), which is
about 8 inches (21 cm) long for fully-grown females and
7 inches (18 cm) long for males
• Pygmy ribbontail catshark (Eridacnis radcliffei) , which
is about 6 to 7 inches (15 - 16 cm) long for fully-grown
females and 7 to 7 1/2 inches (18 - 19 cm) long for males.
MOST DANGEROUS
The oceanic white-tipped sharks are the
most fearless predators. Jacques-Yves
Cousteau says that it is: "the only species
of shark that is never frightened by the
approach of a diver, and they are the most
dangerous of all sharks."
FASTEST
The fastest swimming sharks are the mako sharks
and blue sharks, which can even leap out of the
water. They are also among the fastest fish.
Estimates of their speed varies; some say that
they can swim at about 60 miles per hour (97
kph), while more conservative estimates are
about 22 mph (35 kph). There hasn't been enough
observation of their speeds to have a definitive
answer.
BIGGEST MOUTH
The whale shark has the biggest mouth
among sharks.
LONGEST TAIL
The thresher sharks have the longest tail among
sharks; the upper lobe of their tails are about the
same length as their bodies.
STRONGEST SHARK BITE
The strongest shark bite belongs to the
dusky shark (Carcharhinus obscurus); its
jaws have been measured to exert 132
pounds (60 kg) of force per tooth (James
Snodgrass and Perry Gilbert, 1965).
MOST COMMON SHARK
The piked dogfish shark (Squalus
acanthias) is very abundant, especially in
the North Atlantic Ocean. It is a small
shark, about 63 inches (1.6 m) long.
LARGEST EGGS
The whale shark was long thought to be
oviparous (an egg 14 inches (36 cm) long was
found in the Gulf of Mexico in 1953; this would
be the largest egg in the world). Recently,
pregnant females have been found containing
hundreds of pups. Whale sharks are viviparous,
giving birth to live young. Newborns are over 2
feet (60 cm) long.
DEEPEST DIVER
The Portuguese shark dives down over 9,000 feet
(2750 m). This is over 1.5 miles.
LONGEST MIGRATION
The Blue shark had been known to migrate
from 1,200-1,700 miles (2000-3000 km) in
a seasonal journey from New York state in
the USA to Brazil.
LARGEST LITTER
One Blue shark was found with 135 pups
in her uterus.