SHARKS!!

What is a shark? they are fish have cartilage instead of bones

Evolution of Sharks sharks have existed for over 400 million years they evolved over 200 million years before the dinosaurs they have gone through very little change over their 400 million years of existence

Size fully grown sharks range in size from 6 inches up to 50 feet most sharks are intermediate in size, and are about the same size as people, 5-7 feet

Varieties of Sharks there are about 350 different species of sharks sharks belong to the group of cartilaginous fish the Elasmobranchii, which includes the sharks, rays and skates

Teeth sharks have up to 3,000 teeth at one time some, like the great white, mako and tiger sharks do not chew their food, but gulp it down whole in large pieces others like the angelshark crush and eat shellfish the whale shark and basking sharks are filter feeders, feeding on large quantities of plankton and small animals

Do Sharks Sleep? they have active and inactive periods some sharks, like the nurse shark, rest motionless on the seafloor others have to keep moving in order to breathe (water has to continually flow across their gills)

Shark Attacks humans taste bad to sharks and we aren’t part of their food web/diet Sharks only eat 2% of their body weight per day, much less than humans eat only about 25 species of sharks are known to attack people in 2013 there were 47 shark attacks in the US (1 death was in Hawaii) –worldwide there were 72 with 10 deaths many more people are killed by bees or lightning

Shark Attacks attacks are rare considering how many people go into the ocean every year the most dangerous sharks to people are the white shark, tiger shark, oceanic whitetip shark and the BULL SHARK (the most frequent attacker of people) million sharks die each year due to humans

Habitat sharks live in oceans and seas all over the world, and even in some rivers and lakes, especially in warmer waters

Shark Reproduction sharks eggs are fertilized inside the female’s body the male shark has claspers, extensions of the pelvic fins that are used to transfer sperm to the female and fertilize her eggs most sharks give birth to live young, but some release eggs that hatch later

Shark Reproduction Cont. the gestation period can be up to almost two years long baby sharks (called pups) are born with a full set of teeth and are fully ready to take care of themselves they quickly swim away, even from their mothers who might eat them litter size ranges from one to two pups to over 100

Three Types of Shark Reproduction: Viviparity Oviparity Ovoviviporous

Viviparity eggs hatch inside females body and the babies are fed by a placenta (much like humans) give live birth number of pups ranges from or more EX: bull shark, whitetip reef shark, and hammerheads Shark Live Birth

Oviparity deposit eggs in the ocean which will hatch later eggs are covered by a tough, leathery membrane eggs may be pouch-like to screw-shaped an egg yolk feeds the embryo EX: zebra shark, swellshark and hornshark

Ovoviviporous the eggs hatch and the babies develop inside the mother there is no placental nourishment the pups eat any unfertilized eggs and each other very few pups in a litter survive until birth due to this form of sibling cannibalism EX: great white shark, nurse shark, and tiger shark

Endangered and Protected Species the largest sharks are decreasing in numbers around the world because of being hunted by people the great white, basking and whale shark are all waning the great white shark is protected along the coast of California and South Africa

Bycatch sharks caught and killed in nets not intended for them.

Finning cutting just the fins off of sharks (a delicacy – shark fin soup) and throwing the rest of the shark (still living!) back into the water Shark Finning Video