Density and distribution of cutaneous sensilla on tails of leopard geckos (Eublepharis macularius) in relation to caudal autotomy

Abstract

The lizard tail is well known for its ability to autotomize and regenerate. Physical contact of the tail by a predator may induce autotomy at the location at which the tail is grasped, and upon detachment the tail may undergo violent, rapid, and unpredictable movements that appear to be, to some degree, regulated by contact with the physical environment. Neither the mechanism by which tail breakage at a particular location is determined, nor that by which environmental feedback to the tail is received, are known. It has been suggested that mechanoreceptors (sensilla) are the means of mediation of such activities, and reports indicate that the density of sensilla on the tail is high. To determine the feasibility that mechanoreceptors are involved in such phenomena, we mapped scale form and the size, density, distribution, and spacing of sensilla on the head, body, limbs, and tail of the leopard gecko. This species has a full complement of autotomy planes along the length of the tail, and the postautotomic behavior of its tail has been documented. We found that the density of sensilla is highest on the tail relative to all other body regions examined; a dorsoventral gradient of caudal sensilla density is evident on the tail; sensilla are more closely spaced on the dorsal and lateral regions of the tail than elsewhere and are carried on relatively small scales; and that the whorls of scales on the tail bear a one to one relationship with the autotomy planes. Our results are consistent with the hypotheses of sensilla being involved in determining the site at which autotomy will occur, and with them being involved in the mediation of tail behavior following autotomy. These findings open the way for experimental neurological investigations of how autotomy is induced and how the detached tail responds to external environmental input.

Ecological associations among epidermal microstructure and scale characteristics of Australian geckos (Squamata: Carphodactylidae and Diplodactylidae)

“…Cutaneous sensilla have also been reported for all geckos examined so far and the numbers we recorded lie within previously reported ranges (Matveyeva & Ananjeva, ; Russell et al. ).…”

“…; Russell et al. ). Detailed epoxy‐resin moulds of live specimens were made according to methods described by Vucko et al.…”

“…; Russell et al. ). Some studies have demonstrated that microstructures vary adaptively with specific life‐histories; for example, subdigital (toepad) microstructures are associated with habitat use in some geckos and iguanids (Höfling & Renous, ; Collins et al.…”

“…Also, the density and distribution of cutaneous sensilla on the tail of the leopard gecko ( Eublepharis macularius ) suggests that they mediate the location of tail breakage and the movement of the tail after breaking (Russell et al. ). Other authors have argued, however, that mechanoreception cannot be the sole functional explanation for the huge variation in the distribution and morphology of cutaneous sensilla in different taxa and suggest additional functions, such as the perception of humidity or temperature (Ananjeva et al.…”

Cutaneous tactile sensitivity before and after tail loss and regeneration in the leopard gecko (Eublepharis macularius)

“…Sensilla are widely distributed across the body of most lizards (e.g. Hiller, 1968Hiller, , 1971Matveyeva and Ananjeva, 1995;Russell et al, 2014), and hence are well positioned to participate in proprioception, tactile sensitivity, and the detection substrate-borne vibrations associated with locomotion, predator/prey detection and possibly communication (Lauff et al, 1993;Sherbrooke and Nagle, 1996;Barnett et al, 1999;Russell, et al, 2014; see also Hetherington, 1989;Virant-Doberlet et al, 2019). For example, the fossorial sandfish lizard (Scincus scincus) uses vibrational information to locate prey on or within a sandy substrate (Hetherington, 1989).…”