Visual modelling supports the potential for prey detection by means of diurnal active photolocation in a small cryptobenthic fish

Bitton, Pierre‐Paul; Christmann, Sebastian Alejandro Yun; Santon, Matteo; Harant, Ulrike K.; Michiels, Nico K.

doi:10.1101/338640

Cited by 4 publications

(12 citation statements)

References 35 publications

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“…In clear waters, red light from the sun is the least abundant part of the spectrum (and virtually absent below 15 m of depth) because red light penetrates least through water, but many organisms convert the deeply penetrating green and blue wavelengths into red. Indeed, the eyes of gammarids, a common prey of round goby, strongly reflect red light [122]. An enhanced red perception through an additional red opsin gene may thus be relevant for round goby predation success below 15 m. In turbid waters, red is the most common part of the light spectrum because long wavelengths experience least scattering [24].…”

Section: Environmental Perceptionmentioning

confidence: 99%

The round goby genome provides insights into mechanisms that may facilitate biological invasions

et al. 2020

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Background: The invasive benthic round goby (Neogobius melanostomus) is the most successful temperate invasive fish and has spread in aquatic ecosystems on both sides of the Atlantic. Invasive species constitute powerful in situ experimental systems to study fast adaptation and directional selection on short ecological timescales and present promising case studies to understand factors involved the impressive ability of some species to colonize novel environments. We seize the unique opportunity presented by the round goby invasion to study genomic substrates potentially involved in colonization success. Results: We report a highly contiguous long-read-based genome and analyze gene families that we hypothesize to relate to the ability of these fish to deal with novel environments. The analyses provide novel insights from the large evolutionary scale to the small species-specific scale. We describe expansions in specific cytochrome P450 enzymes, a remarkably diverse innate immune system, an ancient duplication in red light vision accompanied by red skin fluorescence, evolutionary patterns of epigenetic regulators, and the presence of osmoregulatory genes that may have contributed to the round goby's capacity to invade cold and salty waters. A recurring theme across all analyzed gene families is gene expansions. Conclusions: The expanded innate immune system of round goby may potentially contribute to its ability to colonize novel areas. Since other gene families also feature copy number expansions in the round goby, and since other Gobiidae also feature fascinating environmental adaptations and are excellent colonizers, further long-read genome approaches across the goby family may reveal whether gene copy number expansions are more generally related to the ability to conquer new habitats in Gobiidae or in fish.

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Section: Environmental Perceptionmentioning

confidence: 99%

The round goby genome provides insights into mechanisms that may facilitate biological invasions

et al. 2020

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“…Using a visual modelling approach, Bitton et al . (2019) showed that the amount of light redirected by a blue ocular spark can indeed generate a perceivable achromatic (luminance) increase in the reflective eyes of gammarid microcrustaceans under natural conditions. Assuming average parameter values of ambient light intensity, ocular spark reflectance and gammarid eye reflectance, average detection distances were in the 1–2 cm range (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…However, triplefins show more ocular sparks in the presence of prey and change the colour of the ocular spark in response to the colour of the background against which prey is presented, suggesting an association (Michiels et al, 2018). Using a visual modelling approach, Bitton et al (2019) showed that the amount of light redirected by a blue ocular spark can indeed generate a perceivable achromatic (luminance) increase in the reflective eyes of gammarid microcrustaceans under natural conditions. Assuming average parameter values of ambient light intensity, ocular spark reflectance and gammarid eye reflectance, average detection distances were in the 1-2 cm range ( Figure 1).…”

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confidence: 98%

“…Recently, it has been shown that micropredatory fish are able to redirect enough downwelling sunlight sideways to illuminate and thus improve visual detection of nearby organisms (Bitton et al, 2019;Santon et al, 2020). This suggestion follows the simple observation that a small amount of light suffices to generate a perceivable increase in eyeshine in the pupils of species with retroreflective eyes, provided the observer possesses a (small) light source near-coaxial to its viewing axis, for example on its iris (Jack, 2014(Jack, , 2015Santon et al, 2018).…”

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confidence: 99%

“…By immediately placing a standardized distance grid on the substrate in the location where the strike had just taken place, we were able to estimate the distance over which the individual approached and subsequently struck at prey by analysing still frames from the recordings. We compared these results with the predictions of Bitton et al (2019) (Wirtz, 1978). The standard length is usually between 3 and 7 cm.…”

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confidence: 99%

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Small benthic fish strike at prey over distances that fall within theoretical predictions for active sensing using light

Neiße

Santon

Bitton

et al. 2020

Journal of Fish Biology

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Small, benthic, cryptic fishes represent a species-rich guild on marine substrates. Most of them are micropredators that feed on crustaceans that are often smaller than 1 mm. Typical examples are seahorses and pipefishes (Syngnathidae), most gobies (Gobiidae), dragonets (Callionymidae) and triplefins (Tripterygiidae). Previous work on the yellow black-headed triplefin Tripterygion delaisi demonstrated that it actively redirects downwelling sunlight sideways using its iris and can use this to locally illuminate objects of interest. We call this form of active sensing using light "diurnal active photolocation". Visual modelling predicted that light redirection can be sufficient to induce a perceivable change in luminance in the eyes of one of its prey species, a cryptic gammarid crustacean (Cheirocratus sp.), over distances of 1-2 cm. Empirical validation, however, was not possible because measurements of predation distances have not been quantified for free-ranging, small, benthic fishes before. Here, we present interaction distances measured from videos of T. delaisi approaching and striking at prey in the field. Out of 160 recordings, we were able to quantify 78 prey approaching distances and 100 striking distances. Approaching distances ranged from 2.1 to 4.1 cm (interquartile range, IQR) and involved one to five approaching steps before the actual strike occurred. The distance over which the final strike took place varied from 0.7 to 1.6 cm (IQR). Both approaching and striking distances increased with fish body size. We conclude that most approaching sequences started too far away to be explained by prey detection through light redirection. Striking distances, however, fell well with the distances predicted by the model. We conclude that if diurnal active photolocation plays a role in prey detection, it is during the final decision whether to strike or not.

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Active sensing with light improves predator detection in a diurnal fish

Santon

Bitton

Dehm

et al. 2018

Preprint

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20Active sensing by means of light is rare. In vertebrates, it is known only from chemiluminescent fish 21 with light organs below their pupils, an anatomical arrangement that is ideal to generate eyeshine in 22 the pupils of nearby organisms. Here, we test whether diurnal fish can achieve the same by 23 redirecting sunlight through reflection instead. We recently showed that small (< 5 cm), benthic, 24 marine triplefin fish actively redirect downwelling light using their iris. We hypothesized that this 25 mechanism allows triplefins to improve detection of a cryptic organism by generating eyeshine in its 26pupil. Here, we tested this by attaching small dark hats to triplefins to shade their iris from 27 downwelling light. Two controls consisted of triplefins with a clear or no hat. These treatments test 28 the prediction that light redirection increases the visual detection ability of triplefins. To this end, we 29 placed treated fish in a tank with a display compartment containing either a stone as the control 30 stimulus, or a scorpionfish, i.e. a cryptic, motionless triplefin predator with retroreflective eyes. After 31 overnight acclimatization, we determined the average distance triplefins kept from the display 32 compartment over two days. Both in the laboratory (n = 15 replicates per treatment) and in a similar 33 field experiment at 15 m depth (n = 43 replicates per treatment) fish kept longer distances from the 34 scorpionfish than from the stone. This response varied between hat treatments: shaded triplefins 35 stayed significantly closer to the scorpionfish in the laboratory and in one of two orientations tested 36 in the field. A follow-up field experiment at 10 m depth revealed the immediate response of 37 triplefins to a scorpionfish. At first, many individuals (n = 80) moved towards it, with shaded 38

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Visual modelling supports the potential for prey detection by means of diurnal active photolocation in a small cryptobenthic fish

Cited by 4 publications

References 35 publications

The round goby genome provides insights into mechanisms that may facilitate biological invasions

The round goby genome provides insights into mechanisms that may facilitate biological invasions

Small benthic fish strike at prey over distances that fall within theoretical predictions for active sensing using light

Active sensing with light improves predator detection in a diurnal fish

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