Many sharks can disguise themselves to look like their surroundings. And this is called "CAMOUFLAGE".
CAMOUFLAGE is a good way to hide from enemies, but it can also be used to help sharks sneak up on their without being seen.
Many small sharks, such as zebra sharks, epaullette sharks, and wobbegongs, have brown or grey patterns to help them blend in with coral and seaweed.
Sharks are often darker on their top half and paler on their bottom half. And this is called COUNTERSHADING.
A shark with COUNTERSHADING, viewed from below will blend with the brightly lit sea surface. Seen from above, it blends with the murky depths. Some wobbegongs sharks have barbels that look like seaweed around their mouths. The fake seaweed tricks fish to come close to the wobbegongs can catch them.
Angel Sharks have very flat, smooth bodies. When they lie on the sandy seabed they become almost invisible.
Shovelnose sharks or guitarfish (really a type of ray) disguises itself for burying itself under the seabed, with only it's eyes sticking out.
The cookie-cutter shark uses patches of lights on its skin to attract hunting fish, seals or whales to come close - then the cookie-cutter takes a bite out of them.
When leopard sharks are young, they have spots to help them hide. As they get older and bigger they don't need so much protection, and the spots fade.
"A silvertip shark demonstrate the COUNTERSHADING that many sharks have pale skin on the underside, and darker skin above."