A morphofunctional study of the jumping apparatus in globular springtails

Abstract

Springtails are notable for their jumping apparatus and latch-mediated spring mechanism. The challenge, in the light of the tiny size and rapid movement of these organisms, has been to understand the morphological intricacies of this spring system. This study takes an approach that integrates SEM, MicroCT, cLSM and high-speed video recordings to understand the composition and functionality of the jumping apparatus in Megalothorax minimus (Neelipleona), Dicyrtomina ornata and Dicyrtomina minuta (Symphypleona). We focus on reconstructing, describing, and understanding the functioning of structures such as basal plates, musculature and furca. The dimensions of the jumping apparatus in Dicyrtomina and Megalothorax differ significantly from those in elongated springtails. A hypothesis of functional coherence between taxa, based on muscle connections and basal plates, is postulated. High-speed video recordings provide information on: 1) furca release timing and function during jumping and self-righting; 2) performance properties of manubrium, dens and mucro in interaction with the ground and in take-off; 3) possible pre-release furca moves. The study underscores the need for further research employing a variety of visualization methods in order to explore additional aspects such as retinaculum unlatching and furca flexion/extension muscles.