Dine or dash? Turbulence inhibits blue crab navigation in attractive–aversive odor plumes by altering signal structure encoded by the olfactory pathway

Abstract

SUMMARYBlue crabs can distinguish and navigate to attractive (food) odors even when aversive odors (injured crab metabolites) are released nearby. Blue crabs in these conditions detect the aversive odor and avoid it, but find the attractive source with nearly the same success rate as when the attractive source is presented alone. Spatially and temporally distinct odor filaments appear to signal to foragers that the two odor sources are not co-located, and hence navigating to the attractive odor entails an acceptable risk of predation. However, environmentally produced turbulence suppresses tracking by homogenizing the two odors; blue crabs fail to track to the attractive source when the aversive source is present, even though turbulence does not substantially inhibit tracking to the attractive source alone. Removal of sensory input from aesthetascs on the antennules, but not chemosensors on the legs, rescues navigation to attractive-aversive dual plumes in turbulent conditions. These results suggest that mixing in the natural environment may amplify the effects of predators by suppressing tracking to food odors when aversive cues are present, and that the olfactory pathway mediates the response.

Context dependence of the olfactory perceptual range in the generalist land snail Cornu aspersum

“…Furthermore, statistical interactions between the effects of the two types of plants are not well supported by data; they could have been an indication that one plant maintained a net attractive or repulsive effect despite the presence of another plant with opposite properties (one stimulus "overshadowing the other"; see, e.g., Perez et al 2015). These results are qualitatively similar to those from previous studies on odour mixtures, in particular mixtures involving both attractive and aversive stimuli (Tomba et al 2001;Weissburg et al 2012;Späthe et al 2013). The absence of a response from individuals exposed to a heterogeneous stimulus (blend of palatable and repulsive plants) can result from two main mechanisms.…”

“…Electrophysiological studies directly investigating neuronal responses to olfactory cues might be able to discriminate these two hypotheses (Peschel et al 1996;Cummins and Wyeth 2014). In blue crabs (Callinectes sapidus M.J. Rathbun, 1896), experiments show that the absence of response to conflicting cues results from the active cancellation of the foraging response (Weissburg et al 2012); a similar mechanism in C. aspersum would tend to support the second hypothesis (i.e., change in response bias).…”

“…However, given our results when different types of plants are mixed and the plant diversity of habitats in which C. aspersum occurs (Iglesias and Castillejo 1999), the relationship between patch size and effective perceptual range might be much more complex. Additionally, the role of wind and air movements in propagating, but also mixing, plant odours needs to be taken into account (Olden et al 2004); in particular, patches located upwind may be detected from farther distances (Schooley and Wiens 2003), but higher turbulence might make discriminating between conflicting odour sources more difficult (Weissburg et al 2012). In light of our results, terrestrial gastro-…”

Simultaneous Sampling of Flow and Odorants by Crustaceans can Aid Searches within a Turbulent Plume

“…Certain cues, such as correlations between the flow kinematics and odorant concentration that the animal sense through the chemoreceptors and mechanoreceptors, can provide valuable information regarding the plume source. However, due to the high intermittency and temporal and spatial variability of the plume, this often reduces the ability of organisms, such as the blue crab, Callinectes sapidus , to successfully navigate to the source of an attractive odor [16]. …”

Odor-background segregation of unknown odorants based on stimulus onset asynchrony in honey bees

“…In particular, odorants that arise from a single source would arrive at the olfactory organ synchronously, whereas odorants that arise from multiple sources would differ in their arrival times (Erskine et al, 2019;Hopfield, 1991). Accordingly, invertebrates can use both spatial and temporal information from odor plumes for odor-background segregation (spatial: (Andersson et al, 2011;Baker et al, 1998;Hopfield and Gelperin, 1989;Weissburg et al, 2012); temporal: (Saha et al, 2013;Sehdev et al, 2019;Szyszka et al, 2012). Remarkably, tobacco hawk moths can segregate odorant sources separated by only 1 millimeter (Baker et al, 1998), and honey bees can use odorant onset asynchronies as short as 6 milliseconds to segregate a known target odorant (odorant with innate or learned valence) from a background odorant (Szyszka et al, 2012).…”