Hermit crab response to a visual threat is sensitive to looming cues

Abstract

Prior work in our lab has shown that an expanding image on a computer screen elicits a hiding response in the Caribbean terrestrial hermit crab (Coenobita clypeatus). We conducted two experiments to identify what properties of the expanding stimulus contribute to its effectiveness as a visual threat. First we found that an expanding geometric star evoked a strong hiding response while a contracting or full-sized stationary star did not. A second experiment revealed that the more quickly the stimulus expanded the shorter the latency to hide. These findings suggest that the anti-predator response to looming stimulus relies heavily on visual cues relating to the manner of approach. The simulated visual threat on a computer screen captures key features of a real looming object that elicits hiding behavior in crabs in the wild.

Evidence of long-term allocentric spatial memory in the Terrestrial Hermit Crab Coenobita compressus

“…Coenobitids (Anomura) have evolved a good aerial sense of distance olfaction that is anatomically centered on the first antenna and behaviorally highly relevant [ 42 ], detecting food as far as 5 m [ 43 , 44 ], however there is some controversy about the existence of an odoriferous chemical substances release system that could be left as a trace in the substrate for spatial orientation in this group [ 22 ]. Though, when in threatening situations, hermit crabs use multisensory channels to evaluate their environment [ 45 ], which has also been observed in other crustaceans as fiddler crabs ( Uca vomeris ) [ 46 ]. More studies are needed to determine the sensory inputs used in this group for the resolution of spatial tasks.…”

Polarization vision in terrestrial hermit crabs

“…The response of hermit crabs to visual stimuli was tested using an approach similar to previous studies on other crab species (How et al 2012(How et al , 2015Shragai et al 2017;Wilby et al 2018;Smithers et al 2019). Briefly, animals were tethered above a treadmill (for terrestrial species) or underwater over a slippery surface (for the marine species) so that they Fig.…”

“…To determine whether C. rugosus and C. brevimanus make use of the polarization of light, we determined their sensitivity to predator-like visual cues presented only in contrasts of polarization using an established playback assay (How et al 2012;Shragai et al 2017;Wilby et al 2018) and compared this to the polarization responses of a fully marine species, Pagurus bernhardus (Linnaeus 1758). To interpret our findings, we analysed the distribution of polarization cues in the visual habitats of the two terrestrial species by collecting footage with a polarization camera on the island of Mahé, Seychelles.…”

A synthesis of deimatic behaviour

“…Deimatic displays may trigger the ‘looming reflex’, an adaptive response to avoid rapidly approaching objects, including predators (Yamawaki, 2011). The looming reflex has been studied across a wide range of species including insects (Rind, Santer & Wright, 2008; Yamawaki, 2011), crustaceans (Shragai et al ., 2017), cephalopods (King & Adamo, 2006; Hanlon & Messenger, 2018) and chordates (Temizer et al ., 2015), and is characterised by receivers taking rapid evasive action to avoid contact with the approaching object. Like startle reflexes, the stimuli that induce this response are specific – looming‐sensitive neurons respond to stimuli that increase rapidly in surface area on the retina (Yilmaz & Meister, 2013).…”