ENTERING THE ESCA
How this anglerfish organ is turned into a beacon that lures prey like moths to a flame
1 PIGMENT
A layer of dark pigmentation prevents light from penetrating the surrounding tissue. This keeps the illicium and the body of the anglerfish hidden until it’s too late for its prey.
2 REFLECTOR
A material called guanine forms a reflective layer in the esca to enhance the light being emitted by the photobacteria.
3
CAVITY
Bioluminescent bacteria are fed into the cavity of the esca, where they carry out light-producing reactions.
4 WINDOW
Sphincter-like muscles open and close around the window of the esca to block light or release it.
5 ILLICIUM
The lightemitting esca is attached to the fish’s body via a structure called the illicium, which acts like a fishing rod pole holding glowing bait.
Fish are drawn in by the glow
5 FACTS LOTS OF LURES
1 WHIPNOSE ANGLER (
GIGANTACTINIDAE
)
Known for swimming upside down in depths of up to around 2,500 metres, these anglerfish dangle their esca from an extra long illicium, which can be several times longer than its body.