Photo & Video: What is it?

It’s the skin of a Wobbegong shark. Fish are covered with scales, but shark skin (and ray skin) is covered with dermal denticles. Dermal denticles are like small teeth: they have a soft centre supplied with blood and nerves, and are coated in a hard, enamel-like material. The denticles don’t grow in size as the animal does (unlike fish scales), instead more denticles are added.
The denticles face backward from the head; this improves hydrodynamics by creating vortices as the shark moves forward through the water. It’s what creates that rough feel when you rub a shark up the wrong way: the animal is smoother to pat if you go front-to-back, which conveniently has your hand moving away from the mouth… be a bit wary, though, as the Wobbegong is reportedly the only shark that can reach around and bite its own tail 😉
—Josh & Liz
Giddy Josh,
Nigel here from the Lady Elliot free dive lady Elliot trip. Just hanging for the footage of the swim through. No pressure just eager
Hi Nigel,
The Lady Elliot freediving video is up:
http://www.underseaproductions.com/blog/freediving-blowhole-lady-elliot-island-video/