A Model of Filiform Hair Distribution on the Cricket Cercus

Abstract

Crickets and other orthopteran insects sense air currents with a pair of abdominal appendages resembling antennae, called cerci. Each cercus in the common house cricket Acheta domesticus is covered with between 500 to 750 filiform mechanosensory hairs. The distribution of the hairs on the cerci, as well as the global patterns of their movement axes, are very stereotypical across different animals in this species, and the development of this system has been studied extensively. Although hypotheses regarding the mechanisms underlying pattern development of the hair array have been proposed in previous studies, no quantitative modeling studies have been published that test these hypotheses. We demonstrate that several aspects of the global pattern of mechanosensory hairs can be predicted with considerable accuracy using a simple model based on two independent morphogen systems. One system constrains inter-hair spacing, and the second system determines the directional movement axes of the hairs.

The morphological heterogeneity of cricket flow-sensing hairs conveys the complex flow signature of predator attacks

“…One key element taken into account when fitting our model (equation (2.28)) was the preferential plane of deflection of the hair. This factor greatly affects the resistance of the hair to rotation [24,25]. Unlike its length, the directionality a of the hair was not known and had to be estimated by regression.…”

“…The red points represent the mean deflection for the same hair subjected to the flow produced by a piston approaching at 58 cm s 21 The fact that a hair has a preferential plane of deflection greatly affects its resistance to rotation. The preferential plane of motion of each sensory hair is an excitatory direction along each hair and its existence can be explained by the anisotropy of the mechanical properties of the socket [24][25][26]. The crucial morphological features conditioning this directionality are the bilaterally symmetrical form of the hair base and the way in which the hair shaft is seated in the socket floor [4].…”

Developmental and activity-dependent plasticity of filiform hair receptors in the locust

“…Filiform hairs are known from the cerci of many insects, such as cockroaches and crickets (Murphey, 1986; Dangles et al, 2006, 2008; Mulder-Rosi et al, 2010; Miller et al, 2011), and from caterpillars, where they mediate escape responses (Tautz and Markl, 1978; Gnatzy and Tautz, 1980; Blagburn and Beadle, 1982; Pflüger and Tautz, 1982; Bacon and Murphey, 1984; Ogawa et al, 2006; Heys et al, 2012). Spiders possess similar, highly sensitive hair sensilla known as trichobothria.…”

Insect-Inspired Distributed Flow-Sensing: Fluid-Mediated Coupling Between Sensors

“…In Figure 21 we show three arrays of increasing size, having 5×5, 9×9 and 17×17 hairs. From these simulations we see that the effect of displacing the flow along the outside of what actual arthropod hairs, with hair-canopies with rather more variability in hair length, diameter and inter-hair distance [14], seated on a rounded shape rather than a flat surface, and airflows with strongly changing properties (frequency content, direction, etc. ), may be exposed to.…”

“…It has also been studied that there exists an 'identifiable' pattern with respect to a hair's preferred directionality and its occurrence on the cercal surface, observed on individuals of the same species [21]. Miller et al [14] have quantitatively characterised the hair patterns on cercus of different crickets Acheta domesticus, determining their lengths, positions and orientations, recalling that the interindividual variation of the patterns of structural organisation was very low. Heys et al [15] have also recently proposed a predictive model of distribution of the preferential orientations of the hairs.…”