Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2778615 | Arthropod Structure & Development | 2013 | 12 Pages |
Jumping bristletails (Archaeognatha) have flagellate antennae with frequent breakpoints, structures destined to break when undue mechanical stress is applied. In natural populations of Petrobius brevistylis at least 67% of animals had broken antennae. In twenty-four trials, all antennae broke at a breakpoint under the animal's weight. Breakpoints consist of two cylinders of laminated cuticle, one stuck inside the other. For half the length of the breakpoint the cylinders are separated by a non-laminated layer of cuticle; thus a tripartite cuticle is formed. During a breakage, the two cylinders slide apart along that non-laminated middle layer that seems to act like a lubricant. While the cylinders pull apart, a thin cuticle unfolds that closes off the new tip of the antenna formed by the outer breakpoint cylinder. Later on, the cylinder is not replaced by a new terminal antennomere. Instead, the antennomere directly proximal to a breakpoint, i.e. the one that after the break forms the last antennomere, already possess the same complement of sensilla as the original terminal antennomere. This includes sensilla basiconica Type A and B found exclusively on these antennomeres and the original terminal antennomere. Breakpoints are common to Archaeognatha and Thysanura, insects that moult throughout their lifetime.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Antennal breakpoints (BPs) consist of two cylinders one inside the other. ► During a break, they slide apart along a middle layer that may act like a lubricant. ► While sliding, a thin cuticle unfolds that closes off the new tip of the antenna. ► The outer cylinder remains as the new tip of the antenna. ► Sensilla basiconica Type A, B only occur on the old tip and proximal to BPs.