Sharks

Sharks

Cartilaginous Fish

SCIENTIFIC CLASSIFICATION

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

FAST FACTS

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.
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.
WEIGHT: No data
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.
GESTATION: Depends on the species: oviparous (egg laying), viviparous (live birth), and ovoviviparous ("egg live birth")
SEXUAL MATURITY: No data
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.
RANGE: Worldwide
HABITAT: Sharks live all over the world, from warm, tropical lagoons to polar seas. Some even inhabit freshwater lakes and rivers.
POPULATION: GLOBAL No data
STATUS: IUCN Several species listed
CITES Several species listed
USFWS Not listed

FUN FACTS

1. Sharks live all over the world, from warm, tropical lagoons to polar seas. Some even inhabit freshwater lakes and rivers!
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.
3. A shark's fusiform (rounded and tapering at both ends) body shape reduces drag and requires minimum energy to swim.
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.
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.
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.
7. For more information about sharks & rays, explore the Sharks & Rays InfoBook.

ECOLOGY AND CONSERVATION

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.

BIBLIOGRAPHY

Eschmeyer, W.N., Herald, E.S. and H. Hammann. Peterson Field Guide to Pacific Coast Fishes. New York. Houghton Mifflin Co. 1983.

Springer, V.G. and J.P. Gold. Sharks in Question: The Smithsonian Answer Book. Washington D.C. Smithsonian Institution Press. 1989.

Wlodarski, L. Sharks: From Fear to Fascination. SeaWorld Education Department Publication. San Diego, SeaWorld, Inc. 1999.

fishbase.org

flmnh.ufl.edu/fish/organizations/ssg/ssg.htm (IUCN Shark Specialist Group)