Insect morphology least three different positions: prognathous, opisthognathous, and hypognathous. In species with prognathous articulation, the head is positioned vertically aligned with the body, such as species of Formicidae; while in a hypognathous type, the head is aligned horizontally adjacent to the body. An opisthognathous head is positioned diagonally, such as species of Blattodea and some Coleoptera. The mouthparts vary greatly between insects of different orders, but the two main functional groups are mandibulate and haustellate. Haustellate mouthparts are used for sucking liquids and can be further classified by the presence of stylets, which include piercing-sucking, sponging, and siphoning. The stylets are
Insect-class gunboat Insect-class gunboat The Insect-class gunboats (or large China gunboats) were a class of small, but well-armed Royal Navy ships designed for use in shallow rivers or inshore. They were intended for use on the Danube against Austria-Hungary (the China name was to disguise their function). The first four ships—"Gnat", "Mantis", "Moth" and "Tarantula"—were first employed during the World War I Mesopotamian Campaign on the Euphrates and Tigris rivers. The ships were designed by Yarrow to operate in shallow, fast-flowing rivers, with a shallow draught and a good turn of speed to counter river flow. They were fitted with two reciprocating