SHARKs

1. SHARKs Shark week!!

2. Cartilaginous Fish • Cartilage is a flexible connective tissue composed of cells and protein. • Fish whose entire skeleton is composed of cartilage are called cartilaginous fish. • They are placed in the class Chondrichthyes • They have been on Earth for millions of years and include Sharks, Rays and skates.

3. Characteristics of Cartilaginous Fish • There are about 600 species of fish that have skeletons made of Cartilage. • They have several characteristics that make them unique. • They have what is called placoid scales, which are actually tiny teeth that are deeply embedded in the skin. • All of the scales point backwards. • To the touch it feels like sandpaper.

4. Characteristics cont. • Sharks have visible gill slits used for breathing, bony fish have gills covered by a flap. • Some sharks live on the bottom and have gill slits on the underside of their body. • They have a pair of breathing holes called spiracles located on their dorsal side behind each eye. • Water passes through the spiracles and flows to the gill chamber. • The mouth is also located on the ventral side of all sharks, and some it is for bottom feeding.

5. Characteristics cont • Fins of sharks are more rigid than bony fish. • Sharks rely on the lift provided by their wing like pectoral fins to prevent sinking and to glide in the water. • Most sharks need to be moving continuosly in order to breathe and survive.

6. SHARKS • There are more than 465 known species of sharks in the ocean • They are apex predators and are found at the top of the food chain • Sharks very greatly in size • The smallest is the pigmy shark (23 cm long) • And the largest is the whale shark which can reach 15 meters in length (the largest fish in the ocean) • Some sharks filter feed (whale shark) while others are active predators.

7. Sharks cont • The nurse shark is a type of shark that lives on the bottom and feed mostly on mollusks. • Other sharks like the White Shark (Carcharadoncarcharias) and the Tiger shark are extreme predators and have been known to attack and even kill humans. • Tiger sharks have been known to eat anything even trash. • Bull sharks can live in both salt and fresh water, and have also been known to attack humans. They also are organisms with the most testosterone making them highly agressive

8. Behavior in Sharks • As a group Sharks have been on Earth for over 300 Million Years. • They are often called living fossils, because they have not changed very much over time. • Sharks have many special adaptations that have enabled them to survive over millions of years.

9. Shark Adaptations • The lateral line organs which is shown as a faint line along each side of a sharks body. • It can pick up sound vibrations over great distances. • The sharks sense of smell is so acute it can detect a drop of blood nearly half a Km away. • Nearly 2/3 of a sharks brain is dedicated to smell. • Sharks also can detect electrical fields given off by organisms. • Tiny pores in the sharks snout contain nerve receptors called the Ampullae of Lorenzini sense the electrical fields generated by organisms.

11. Shark adaptations cont • Many sharks have to be in constant motion because if they do not swim they can sink to the bottom. • Swimming also supplies oxygenated water to the gills • Also a shark has a large oily liver that increases buoyancy.

12. Reproduction in Sharks • Sharks differ from most other fish in the way they reproduce. • They have internal fertilization. • Male sharks have 2 organs called claspers, located between their pelvic fins. • They transfer sperm into the females reproductive tract. • Some sharks have internal development and live-bear their young. • Others lay eggs called mermaids purses which are often found washed up on the beach • Some live bearing young begin their predatory behavior in the womb cannibalizing each other in the womb. • Some sharks carry live young for up to two years before they hatch, and some eggs take more than a year to develop.

13. Some Shark facts • Sharks are a threatened species and are often caught by fisherman for their dorsal fin which is used to make shark fin soup. • Between 20 and 100 million sharks are killed each year. • The rest of the shark is inedible and is cast aside and the shark dies. • Sharks have rows upon rows of teeth. When a tooth is lost a new one rotates into its place. • Sharks live in all ocean waters and can be found at all depths. A six gilled shark can live miles deep in the dark ocean.

14. Shark Facts continued • Some sharks are solitary animals while others hunt together in groups. • A hammerhead shark has the ability to see 300 Degrees with their odd shaped head. • Great Whites can swim at speeds up to 30 km per hour. • Each year there are about 50 to 70 confirmed shark attacks and 5 to 15 shark-attack fatalities around the world • The US has about 16 attacks each year and average one fatal attack every two years.

15. Shark Facts • Some sharks stay in one area for their entire lives, others migrate all across the globe. • Sharks do not sleep. Rather, they experience alternating periods of activity and rest. • Sharks have long life spans and don't reach sexual maturity until they are 12 to 20 years old. • The majority of Sharks live for 20-30 years while others have been thought (like the whale shark) to live up to 100 years.