Nudibranch (sea slug)

A nudibranch is a soft-bodied sea slug that lacks a shell. These small creatures come in many shapes. You will find them mostly in tropical waters like Anilao or Koh Tao where they feed on sponges. Most species stay under 5 cm because they rely on bright colors to warn predators of their toxicity. I often spend 20 minutes searching a single coral head for a specific color pattern. Look closely at the underside of rubble. A common mistake is moving too fast while searching for them. Slow your buoyancy so that you do not stir up silt before you see the animal. Check your light angles to reveal their true colors.