The bi­ol­ogy be­hind a chameleon’s light­ning-quick licker

World of Animals - - Tongue-Fu Masters -

Hy­oid bone

This bone an­chors the tongue in the lower jaw. When ready to fire, the hy­oid is lifted up and out, rais­ing the tongue above the jaw­line ready to fire.

Re­trac­tor mus­cle

Tightly wound coils of col­la­gen tis­sue – the ‘hyo­glos­sus com­plex’ – con­certina in lay­ers around the hy­oid gleam. When at rest this is where po­ten­tial en­ergy is stored.

Ac­cel­er­a­tor mus­cle

Con­tract­ing this ring-shaped mus­cle re­leases the stored en­ergy. As the re­trac­tor com­plex stretches out the tongue shoots for­ward.

Reel­ing it in

Hy­oid gleam

Which­ever di­rec­tion this cylin­dri­cal bone is point­ing is where the tongue-tip will travel; it’s es­sen­tially the bolt in this bi­o­log­i­cal cross­bow.

Sticky end

The tongue ter­mi­nates with a firm pad sur­rounded by folds of softer tis­sue. On im­pact, the squidgy tis­sue con­tin­ues to move for­wards, en­gulf­ing the vic­tim. Re­tract­ing the tongue with the en­snared prey is a far slower process, rel­a­tively speak­ing, re­ly­ing on the con­trac­tion of the re­trac­tor mus­cle.

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