Unlike the bony fish, sharks & rays have a light-weight, flexible and durable skeleton made of cartilage. It's the same grisly stuff your ears and nose tip are made of, and it's only about half the normal density of bone. We have a chance to see sharks & rays at all the dive sites around Koh Lanta.
This light-weight skeleton allows sharks and rays to swim faster and use less energy than other bony fishes. As sharks age, calcium salts begin to accumulate in the cartilage skeleton to strengthen it. That's why dried shark jaws feel heavy and solid like bone.
Sharks and Rays have five to seven pairs of gill clefts which can open independently, rigid dorsal fins and small bony, pointed, tooth-shaped scales on the skin.
The teeth are arranged in multiple rows and are replaced continually, with some species of shark getting through up to 35,000 teeth in their lifetime.
Unlike other fish which rely on swim bladders for buoyancy, sharks have large livers full of a low-density oil which provides buoyancy. The oil-filled liver can be up to 20% of the total animal weight.
Most sharks have excellent eyesight, enhanced by small electroreceptor organs near their eyes, nose and mouth that can sense electromagnetic fields and temperature changes in the sea. These special sensing organs look like small black spots and can help sharks to sense food many miles away.
Sharks and rays reproduce by internal fertilization, and usually lay large, heavy-shelled eggs or give birth to live young.
Can I see sharks when diving around Koh Lanta?
Yes, if you're lucky you might see black tip reef sharks, leopard sharks, or even a whale shark while you're diving around Koh Lanta.
