The feeding apparatus of ants: an overview of structure and function

Abstract

Ants are a dominant family of eusocial terrestrial insects with a diversity of ecologies, lifestyles and morphologies. Ant diet preferences range from strict carnivory through omnivory to almost complete herbivory in species feeding on seeds or exudates of plant-sucking insects. While several studies have investigated ant feeding performance on different substrates, comparatively little is known about the functional morphology of the structures involved in food uptake or their diversification across the ants. To take stock of our current knowledge, we give an overview of how adult ants ingest food, followed by a morphological description of the mouthparts, preoral space and cephalic sucking pump. The mandibles are the most prominent mouthparts and have received considerable attention in the literature, so we focus on the maxillae and labium here. We present current hypotheses for the movement patterns of these parts and discuss morphological differences among ants that may be related to their ecological diversity. Finally, we give short comparisons of the ant condition with some other insects and vertebrates, as well as an outlook summarizing gaps in our knowledge. This sets the stage for future studies elucidating the connections between ant feeding mechanisms and mouthpart evolution. This article is part of the theme issue ‘Food processing and nutritional assimilation in animals’.

Introduction: food processing and nutritional assimilation in animals

“…Oral feeding performance is defined in this issue through a range of conventional measures. Püffel et al [40] define mandibular performance in feeding ants using bite force production, and Richter & Economo [38] discuss performance though food uptake rates and feeding duration. Similarly, Bels et al [55] [21] all assess feeding performance through jaw and tongue kinematics, as well as muscle performance (length-change), whereas Panagiotopoulou et al [56] use bone strain.…”

“…Püffel et al . [ 40 ] define mandibular performance in feeding ants using bite force production, and Richter & Economo [ 38 ] discuss performance though food uptake rates and feeding duration. Similarly, Bels et al .…”

“…rigid body kinematics, three-dimensional motion capture and XROMM), similar techniques have only recently been adapted to understand chewing and biting in insects [39]. Articles in this special issue focused on ants [38][39][40] present novel frameworks to quantitatively characterize insect mandible motion and derive bite forces across the insect phylogeny. Further development of these methods will inspire future researchers to pursue quantitative comparisons of the mechanics of feeding across a wider range of invertebrates and vertebrates.…”

“…There are profound differences but also remarkable similarities between the feeding systems of vertebrate and invertebrate animals that this special issue highlights (e.g. [ 38 – 40 ]). While researchers for decades have used highly advanced and technical methods to study vertebrate feeding kinematics (e.g.…”

Mechanical and elemental characterization of ant mandibles: consequences for bite mechanics

“…Along with these cross-links, it is known that ant species can incorporate minerals into their cuticle [72], similar to the cuticles of crustaceans. All of this highlights the relevance of determining the cuticle elemental composition, as is being explored in the chitinous structures of several mollusc lineages [26,[73][74][75], especially regarding structures heavily employed to perform multiple tasks, like ant mandibles [7,76,77].…”