Hypostome

from Wikipedia, the free encyclopedia

The hypostome ( old Gr. Ὑπό hypó 'under [half]' and στόμα stóma 'mouth') is the mouth of cnidarians and articulated animals .

Hypostome in ticks

In the case of a tick bite , the hypostome is used after the cut with the bite claws. The tick is a tongue-like and barbed part of the oral apparatus that is inserted into the cut.

Hypostome in trilobites

The hypostome is a plate on the underside of the cephalon in trilobites . It was probably part of the oral apparatus. The shape and the positioning of this hypostome are essential features in the systematic classification of the trilobite species.

Arrangements of the hypostome on the underside of the cephalon

Conterminant positioning

Hypostome of an Isotelus

In what is known as conterminant positioning, the hypostome is attached to the rostral plate . The front of the glabella on top is flush with the front of the hypostome.

Natante positioning

In the so-called natant positioning, the hypostome lies within the underside of the cephalon and is therefore no longer connected to the rostral plate. With this positioning, too, the glabella front is flush with the hypostome front.

Independent positioning

The hypostome is attached to the doublets but is positioned independently of the glabella . The glabella is usually longer and thus overlaps the hypostome.

Individual evidence

  1. ^ Wilhelm Gemoll : Greek-German school and hand dictionary . G. Freytag Verlag / Hölder-Pichler-Tempsky, Munich / Vienna 1965.

Web links