Blue tang
Depth: 25 m · Sunlight Zone
The blue tang glows bright blue and carries a sharp blade near its tail, almost like a little scalpel. That is how it got its name. When it flicks the blade out, it can defend itself against attackers. By day it nibbles algae off the coral.
For scientists
On its tail base the blue tang carries a sharp, folding bony blade on each side (hence the name), which it raises to defend itself. As an algae grazer it keeps the coral free of overgrowth and so is important for reef health. Its glowing blue color comes not from blue pigment but from light-bending structures in its skin.
🌊 Swim straight to it in 3D