SHARKS

Parts of shark

sharks are a type of fish with a highly streamlined body. sharks were know more  than 420 million years ago.

they have diversified in 440 species  

(there are some of them)

ANGELSHARK	BASKING SHARK	BLACKTIP REEF SHARK	BLUE SHARK
BLUNTNOSE SIXGILL SHARK	BONNETHEAD SHARK	BROADNOSE SEVENGILL SHARK	BULL SHARK
DOGFISH SHARK	GALAPAGOS SHARK	GOBLIN SHARK	GREAT WHITE SHARK
HAMMERHEAD SHARK	LEMON SHARK	MANTA RAY	MAKO SHARK
NURSE SHARK	PORBEAGLE SHARK	SPINED PYGMY SHARK	THRESHER SHARK
TIGER SHARK	WHALE SHARK

multiple rows of replacement teeth groove on the inside of the jaw and steadily move forward as in a conveyor belt. some sharks lose about 30 000 teeth in their lifetime

                                                   

 shark skeleton are very different  from bony fish and terrestrial vertebrates. they have skeletons made of cartilage and connective issue. cartilage's flexible, durable. this help to save energy
They also do not have a swim bladder, the air filled balloon-like organ that keeps most fish upright. Sharks have gill slits but no gill-cover, which is common to most bony fish. Because they have no swim bladder to keep them buoyant, sharks sink when not swimming. Shark's bodies are heavier than water and most sharks are constantly on the move. By moving forward with their mouths open,
sharks move water across their gills for breathing.  The larger species produce live young that are
fully formed, miniature versions of their parents. Mother sharks offer no food or protection for theiryoung. Young sharks do have a fighting chance, though, as they are born with a full set of teeth and the ability to swim.


Nowadays they are in a danger of being extinct. more people are dying from eating shark's meat than from shark's attack so the question is who's more dangerous?