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| SCIENTIFIC
CLASSIFICATION |
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| COMMON
NAME: |
sharks |
| KINGDOM: |
Animalia |
| PHYLUM: |
Chordata |
| CLASS: |
Chondrichthyes |
| SUBCLASS: |
Elasmobranchii |
| SUPERORDER: |
Selachii |
| ORDER: |
No
data |
| FAMILY: |
No
data |
| GENUS
SPECIES: |
There
are approximately 350 different species of sharks |
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| DESCRIPTION: |
Sharks
are fishes and most have the typical fusiform body
shape. Like other fishes, sharks are ectothermic
(cold-blooded), live in water, have fins, and breathe
with gills. However, sharks differ from Osteichthyes
fish. One difference is that a shark's skeleton
is made of cartilage instead of bone. Another visible
difference is that bony fish tend to have a single
gill slit, whereas all but two species of shark
have 5 gill slits. |
| MALE |
External
claspers located on the far underside of the body
- forward of the caudal fin - distinguish males. |
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| SIZE: |
The
largest shark is the 13.7 m (45 ft.) whale shark.
The 22-25 cm (8.7-9.8 in.) midwater shark and pygmy
ribbontail catshark are among the smallest. |
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| DIET: |
The
characteristic teeth of each species are adapted
to that particular species' diet. The teeth may
be serrated or smooth. Most are used for seizing
prey, cutting, or crushing. Some sharks are probably
not very picky about what they eat. But certain
kinds of sharks eat some foods more than others.
For example, hammerhead sharks eat mostly stingrays.
Tiger sharks eat sea turtles. And whale sharks eat
plankton. |
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| GESTATION: |
Depends
on the species: oviparous (egg laying), viviparous
(live birth), and ovoviviparous ("egg live
birth") |
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| LIFE
SPAN: |
Because
sharks grow slowly and have a low reproductive rate,
scientists believe that sharks are relatively long-lived.
As of yet, there is no accurate way to determine
the age and lifespan of a shark. |
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| HABITAT: |
Sharks
live all over the world, from warm, tropical lagoons
to polar seas. Some even inhabit freshwater lakes
and rivers. |
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| POPULATION: |
GLOBAL |
No
data |
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| STATUS: |
IUCN |
Several
species listed |
| CITES |
Several
species listed |
| USFWS |
Not listed |
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| 1. |
Sharks
live all over the world, from warm, tropical lagoons
to polar seas. Some even inhabit freshwater lakes
and rivers! |
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| 2. |
Sharks
are fishes. Like other fishes, sharks are cold-blooded,
have fins, live in the water, and breathe with gills.
A shark's skeleton is made of cartilage. |
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| 3. |
A
shark's fusiform (rounded and tapering at both ends)
body shape reduces drag and requires minimum energy
to swim. |
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| 4. |
Sharks
eat far less than most people imagine. Cold-blooded
animals have a much lower metabolism than warm-blooded
animals. In fact, in a zoological environment, a
shark eats about 1-10% of its total body weight
each week. Studies on sharks in the wild show similar
food intake. |
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| 5. |
Only
32 (of roughly 350) shark species have ever been
known to attack people. Like other wild animals,
most sharks would rather avoid you. Sharks that
have attacked probably mistook people for food or
may have attacked to protect their territory. |
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| 6. |
Unlike
bony fish, sharks teeth are not anchored in their
jaw and sharks often lose teeth, especially when
feeding. Sharks are equipped with three or more
rows of teeth, so when a tooth is lost another tooth
quickly replaces it. A single shark may have as
many as 30,000 teeth throughout the course of its
life. |
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| 7. |
For
more information about sharks, explore the sharks
& rays info book. |
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Over
the years, people have used sharks for food, medicines,
and vitamins; shark teeth for weapons and jewelry;
and shark skin for sandpaper. But today some shark
populations are on the brink of extinction. Why?
Shark meat is a popular food (with many sharks
being caught only for human consumption of their
fins). And thousands of sharks are caught by accident,
snagged in nets set out to catch other kinds of
fish.
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| Eschmeyer,
W.N., Herald, E.S. and H. Hammann. Peterson Field
Guide to Pacific Coast Fishes. New York. Houghton
Mifflin Co. 1983. |
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| Springer,
V.G. and J.P. Gold. Sharks in Question: The Smithsonian
Answer Book. Washington D.C. Smithsonian Institution
Press. 1989. |
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| Wlodarski,
L. Sharks: From Fear to Fascination. SeaWorld
Education Department Publication. San Diego, SeaWorld,
Inc. 1999. |
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| http://www.fishbase.org/ |
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| http://www.flmnh.ufl.edu/fish/organizations/ssg/ssg.htm
(IUCN Shark Specialist Group) |
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