scholarly journals Behavioural evidence for polychromatic ultraviolet sensitivity in mantis shrimp

2018 ◽  
Vol 285 (1884) ◽  
pp. 20181384 ◽  
Author(s):  
Michael J. Bok ◽  
Nicholas W. Roberts ◽  
Thomas W. Cronin
Keyword(s):  
Narrow Band ◽  
Visible Range ◽  
Mantis Shrimp ◽  
Visual Systems ◽  
Uv Vision ◽  
Wavelength Discrimination ◽  
Behavioural Experiments ◽  
Polarization Detection ◽  
Behavioural Evidence ◽  
Uv Range

Stomatopod crustaceans are renowned for their elaborate visual systems. Their eyes contain a plethora of photoreceptors specialized for chromatic and polarization detection, including several that are sensitive to varying wavelength ranges and angles of polarization within the ultraviolet (UV) range (less than 400 nm). Behavioural experiments have previously suggested that UV photoreception plays a role in stomatopod communication, but these experiments have only manipulated the entire UV range. Here, using a behavioural approach, we examine UV vision in the stomatopod Haptosquilla trispinosa . Using binary trained choice assays as well as innate burrow-choice experiments, we assessed the ability of H. trispinosa to detect and respond to narrow-band LED stimuli peaking near 314 nm (UVB) versus 379 nm (UVA) in wavelength. We find that H. trispinosa can discriminate these stimuli and appears to display an aversive reaction to UVB light, suggesting segregated behavioural responses to stimuli within the UV range. Furthermore, we find that H. trispinosa can discriminate stimuli peaking near 379 nm versus 351 nm in wavelength, suggesting that their wavelength discrimination in the UV is comparable to their performance in the human-visible range.

scholarly journals The colour of success: does female mate choice rely on male colour change in the chameleon Furcifer pardalis?

2020 ◽  
Vol 223 (20) ◽  
pp. jeb224550
Author(s):  
Alexis Y. Dollion ◽  
Anthony Herrel ◽  
Olivier Marquis ◽  
Mathieu Leroux-Coyau ◽  
Sandrine Meylan
Keyword(s):  
Mate Choice ◽  
Colour Change ◽  
Female Mate Choice ◽  
The Body ◽  
Body Region ◽  
Visible Range ◽  
Female Mate ◽  
Behavioural Experiments ◽  
Uv Range

ABSTRACTColour change is involved in various functions ranging from thermo- and hydroregulation to camouflage and communication. The role of colour change in communication has received increased attention over the past few decades, yet has been studied predominantly in the context of intrasexual competition. Here, we investigate the role of colour change in mate choice in an animal that can change its colour, the panther chameleon (Furcifer pardalis). We conducted behavioural experiments and colour analysis to investigate whether colour changes, including in the UV range, are involved in mate choice. This study presents evidence of female mate choice for specific aspects of colour change in courting males, both in the visible (i.e. human visible range: 400–700 nm) and the UV range. Females chose males exhibiting more saturation changes regardless of the body region and spectral range. In addition, females chose males showing fewer brightness changes at the level of the lateral line and males showing lower hue changes at the level of the bands and the interbands, in the visible range. At UV wavelengths, selected males showed more brightness changes and higher maximum brightness. These results suggest that male colour change is important in female mate choice in the panther chameleon.

scholarly journals Enhanced ultraviolet absorption in graphene by aluminum and magnesium hole-arrays

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xueling Cheng ◽  
Yunshan Wang
Keyword(s):  
Numerical Study ◽  
Uv Spectroscopy ◽  
Single Layer ◽  
Hybrid Structure ◽  
Uv Absorption ◽  
Single Layer Graphene ◽  
Visible Range ◽  
Uv Spectrum ◽  
Hole Arrays ◽  
Uv Range

AbstractOptoelectronic devices in the UV range have many applications including deep-UV communications, UV photodetectors, UV spectroscopy, etc. Graphene has unique exciton resonances, that have demonstrated large photosensitivity across the UV spectrum. Enhancing UV absorption in graphene has the potential to boost the performance of the various opto-electronic devices. Here we report numerical study of UV absorption in graphene on aluminum and magnesium hole-arrays. The absorption in a single-layer graphene on aluminum and magnesium hole-arrays reached a maximum value of 28% and 30% respectively, and the absorption peak is tunable from the UV to the visible range. The proposed graphene hybrid structure does not require graphene to be sandwiched between different material layers and thus is easy to fabricate and allows graphene to interact with its surroundings.

scholarly journals Behavioural evidence for self-medication in bumblebees?

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 73 ◽  
Author(s):  
David Baracchi ◽  
Mark J. F. Brown ◽  
Lars Chittka
Keyword(s):  
Secondary Metabolites ◽  
Sucrose Solution ◽  
Parasite Load ◽  
Foraging Activity ◽  
Self Medication ◽  
Crithidia Bombi ◽  
Nicotine Consumption ◽  
Behavioural Experiments ◽  
Behavioural Tests ◽  
Behavioural Evidence

The presence of antimicrobial secondary metabolites in nectar suggests that pollinators, which are threatened globally by emergent disease, may benefit from the consumption of nectars rich in these metabolites. We tested whether nicotine, a nectar secondary metabolite common in Solanaceae and Tilia species, is used by parasitized bumblebees as a source of self-medication, using a series of toxicological, microbiological and behavioural experiments. Caged bees infected with Crithidia bombi had a slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity, though nicotine had an appetite-reducing effect overall. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion, the protozoan’s viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in starved bees but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees, suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nicotine consumption did not affect bee lifespan but the reduction in the parasite load may have other likely unexplored subtle benefits both for individual bees and their colony.  Potential evidence for self-medication is discussed. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.

For My Eyes Only

Secret Worlds ◽  
2021 ◽  
pp. 53-84
Author(s):  
Martin Stevens
Keyword(s):  
Visual Processing ◽  
Colour Vision ◽  
Green Light ◽  
Light Spectrum ◽  
Colour Perception ◽  
Mantis Shrimp ◽  
Uv Vision ◽  
Different Dimensions ◽  
Different Parts ◽  
Polarisation Vision

This chapter explores how vision is used by animals and the diversity in ways of seeing. It first details how colour vision works, focusing on the example of honeybees, which, like humans, are trichromatic and have good colour vision. Bees have a dedicated ultraviolet (UV) receptor, and then one for seeing shortwave (blue) and mediumwave (green) light. Other animals deviate more substantially, in that they have either more or fewer receptors used in colour vision, and hence different ‘dimensions’ of colour perception. The chapter then considers how jumping spiders use UV vision in identifying known or suitable prey species, as well as in mating. It also looks at polarisation vision in mantis shrimp. Mantis shrimp are bizarre in the number of receptors they have, each sensitive to different parts of the light spectrum. Finally, the chapter assesses how toads recognize prey from non-prey. The toad’s visual system acts as a ‘feature detector’ based on several stages of visual processing, producing a quick and appropriate response to a set of criteria that reliably encode objects of particular importance—in this case, food.

scholarly journals Contrast sensitivity and behavioural evidence for lateral inhibition in octopus

2019 ◽  
Vol 15 (5) ◽  
pp. 20190134 ◽  
Author(s):  
Luis Nahmad-Rohen ◽  
Misha Vorobyev
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Lateral Inhibition ◽  
Neural Processing ◽  
Visual Systems ◽  
Maximum Value ◽  
Fixation Reflex ◽  
First Time ◽  
The Brain ◽  
Behavioural Evidence

Behavioural contrast sensitivity in Octopus tetricus was measured in the range of 0.05–12 cycles per degree (cpd) using a fixation reflex. We show that the contrast sensitivity reaches its maximum (between 1 and 4%) at 0.3 cpd, and decreases to approximately half of the maximum value at the lowest spatial frequency. Reduction of sensitivity at low spatial frequency is a signature of lateral inhibition in visual systems. In vertebrates and insects, lateral inhibition helps to overcome the bottleneck of encoding information into spikes. In octopus, photoreceptors generate spikes themselves and are directly connected to the brain through their axons. Therefore, the neural processing occurring in the octopus brain cannot help overcome the bottleneck of encoding information into spikes. We conclude that, in octopus, either the lateral inhibition occurs in the brain after information has been encoded into spikes, or photoreceptors inhibit each other. This is the first time behavioural contrast sensitivity has been measured in a cephalopod.

Potential material for narrow‐band detectors in the visible range

1981 ◽  
Vol 39 (1) ◽  
pp. 79-80 ◽  
Author(s):  
N. V. Joshi ◽  
J. Martin ◽  
P. Quintero
Keyword(s):  
Narrow Band ◽  
Visible Range

scholarly journals EFFECT OF Ag NANOPARTICLE ON THE PHOTOCATALYTIC ACTIVITY OF TIO2 NANOTUBES

2018 ◽  
Vol 54 (1A) ◽  
pp. 42
Author(s):  
Le Thi Ngoc Tu
Keyword(s):  
Photocatalytic Activity ◽  
Tio2 Nanotubes ◽  
Visible Range ◽  
Ag Nanoparticle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Ag Particles ◽  
Structure Morphology ◽  
Uv Range

The TiO2 nanotubes were fabricated by the hydrothermal method. Then, Ag nanoparticles with the varying ratio were attached on the TiO2 nanotubes by photoreduction. The characteristics of structure, morphology, chemical composition and of TiO2 nanotubes modified Ag (Ag-TNTs) was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and the absorption spectral of Methylene blue (MB) solution. The results showed that Ag-TNTs have fairly uniform length with Ag particles immobilized on the tube. The photocatalysis TiO2 nanotubes (TNTs) is higher than Ag-TNTs in UV range and lower than Ag-TNTs in the visible light. And the photocatalytic activity of Ag-TNTs with 5 wt.% Ag is highest in the visible range.

Escape behaviour in the stomatopod crustacean Squilla mantis, and the evolution of the caridoid escape reaction

2000 ◽  
Vol 203 (2) ◽  
pp. 183-192 ◽  
Author(s):  
W.J. Heitler ◽  
K. Fraser ◽  
E.A. Ferrero
Keyword(s):  
Escape Response ◽  
Large Diameter ◽  
Mechanical Vibration ◽  
Maximal Response ◽  
Escape Behaviour ◽  
Mantis Shrimp ◽  
Threshold Response ◽  
Low Threshold ◽  
Escape Reaction ◽  
Behavioural Evidence

The mantis shrimp Squilla mantis shows a graded series of avoidance/escape responses to visual and mechanical (vibration and touch) rostral stimuli. A low-threshold response is mediated by the simultaneous protraction of the thoracic walking legs and abdominal swimmerets and telson, producing a backwards ‘lurch’ or jump that can displace the animal by up to one-third of its body length, but leaves it facing in the same direction. A stronger response starts with similar limb protraction, but is followed by partial abdominal flexion. The maximal response also consists of limb protraction followed by abdominal flexion, but in this case the abdominal flexion is sufficiently vigorous to pull the animal into a tight vertical loop, which leaves it inverted and facing away from the stimulus. The animal then swims forward (away from the stimulus) and rights itself by executing a half-roll. A bilaterally paired, large-diameter, rapidly conducting axon in the dorsal region of the ventral nerve excites swimmeret protractor motoneurons in several ganglia and is likely to be the driver neuron for the limb-protraction response. The same neuron also excites unidentified abdominal trunk motoneurons, but less reliably. The escape response is a key feature of the malacostracan caridoid facies, and we provide the first detailed description of this response in a group that diverged early in malacostracan evolution. We show that the components of the escape response contrast strongly with those of the full caridoid reaction, and we provide physiological and behavioural evidence for the biological plausibility of a limb-before-tail thesis for the evolution of the escape response.

scholarly journals Aerosol Optical Depth and the Global Brewer Network: A Study Using U.K.- and Malaysia-Based Brewer Spectrophotometers

2012 ◽  
Vol 29 (6) ◽  
pp. 857-866 ◽  
Author(s):  
Wilawan Kumharn ◽  
John S. Rimmer ◽  
Andrew R. D. Smedley ◽  
Toh Ying Ying ◽  
Ann R. Webb
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Climate Models ◽  
Visible Range ◽  
Depth Data ◽  
The United Kingdom ◽  
Brewer Spectrophotometer ◽  
Sky Conditions ◽  
Aerosol Optical Depth Data ◽  
Uv Range

Abstract Aerosols play an important role in attenuating solar radiation reaching the earth's surface and are thus important inputs to climate models. Aerosol optical depth is routinely measured in the visible range but little data in the ultraviolet (UV) are available. In the UV range it can be determined from Langley plots of direct-sun measurements from the Brewer spectrophotometer (where conditions allow) and can also be determined as the residual once the ozone and sulfur dioxide have been accounted for in the extinction observed during a normal Brewer direct-sun measurement. By comparing aerosol optical depth derived from Brewer direct-sun data in both the United Kingdom and Malaysia, two very different locations, it is determined that while most of the existing global Brewer network could contribute to aerosol optical depth data, further analysis, such as calculation of the Ångström parameter, would be dependent on latitude and sky conditions.

scholarly journals Forecasting of UV-Vis absorbance time series using artificial neural networks combined with principal component analysis

2016 ◽  
Vol 75 (4) ◽  
pp. 765-774
Author(s):  
Leonardo Plazas-Nossa ◽  
Thomas Hofer ◽  
Günter Gruber ◽  
Andres Torres
Keyword(s):  
Neural Networks ◽  
Principal Component Analysis ◽  
Time Series ◽  
Artificial Neural Networks ◽  
Principal Component ◽  
Component Analysis ◽  
Series Data ◽  
Visible Range ◽  
Artificial Neural ◽  
Uv Range

This work proposes a methodology for the forecasting of online water quality data provided by UV-Vis spectrometry. Therefore, a combination of principal component analysis (PCA) to reduce the dimensionality of a data set and artificial neural networks (ANNs) for forecasting purposes was used. The results obtained were compared with those obtained by using discrete Fourier transform (DFT). The proposed methodology was applied to four absorbance time series data sets composed by a total number of 5705 UV-Vis spectra. Absolute percentage errors obtained by applying the proposed PCA/ANN methodology vary between 10% and 13% for all four study sites. In general terms, the results obtained were hardly generalizable, as they appeared to be highly dependent on specific dynamics of the water system; however, some trends can be outlined. PCA/ANN methodology gives better results than PCA/DFT forecasting procedure by using a specific spectra range for the following conditions: (i) for Salitre wastewater treatment plant (WWTP) (first hour) and Graz West R05 (first 18 min), from the last part of UV range to all visible range; (ii) for Gibraltar pumping station (first 6 min) for all UV-Vis absorbance spectra; and (iii) for San Fernando WWTP (first 24 min) for all of UV range to middle part of visible range.

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