Osmaterium

Swallowtail caterpillar with everted osmaterium

Papilio glaucus caterpillar with everted osm material

The osmaterium is a nuchal fork that sits between the head and the first thorax segment of the caterpillars of knightly butterflies (Papilionidae). It is used to deter predators. The osmaterium, which is folded in its normal state and is therefore invisible, is everted in the event of danger by forcing in hemolymph fluid. In addition, the caterpillar bends the front part of the body upwards to look more threatening. In addition to the mostly yellow, orange or reddish color and the peculiar, bulky, fleshy shape that irritates enemies, the caterpillar with glands located on this organ sends out a foul-smelling secretion that causes enemies such as z. B. ants flee. This scent is produced by terpenes , the composition of which varies depending on the species. If the caterpillar is disturbed several times and it notices that its reaction is unsuccessful, it flees.

credentials

^ T. Eisner, YC Meinwald: The defensive secretions of a caterpillar (Papilio). In: Science. 150, 3704, 1965, pp. 1733-1735 (1965).

Web links

Commons : Osmaterium - collection of images, videos and audio files

Osmaterium - neck fork ( Memento from September 7, 2008 in the Internet Archive )

[Eisner/Meinwald-1] T. Eisner, YC Meinwald: The defensive secretions of a caterpillar (Papilio). In: Science. 150, 3704, 1965, pp. 1733-1735 (1965).