Daniel Osorio

University of Sussex · Department of Evolution, Behaviour and Environment

In many animals, ultraviolet (UV) vision guides navigation, foraging, and communication, but few studies have addressed the contribution of UV signals to colour vision, or measured UV discrimination thresholds using behavioural experiments. Here, we tested UV colour vision in an anemonefish (Amphiprion ocellaris) using a five-channel (RGB-V-UV) LED...

Michael (Mike) Land made lasting contributions to physiological optics of diverse animals and to understanding how animals and humans move their eyes. He combined a keen interest in natural history and evolution with elegant and accessible mathematical accounts of optics and vision. In the early part of his career he discovered focusing mechanisms...

In vertebrate vision, early retinal circuits divide incoming visual information into functionally opposite elementary signals: On and Off, transient and sustained, chromatic and achromatic. Together these signals can yield an efficient representation of the scene for transmission to the brain via the optic nerve. However, this long-standing interpr...

An object’s colour, brightness and pattern are all influenced by its surroundings, and a number of visual phenomena and “illusions” have been discovered that highlight these often dramatic effects. Explanations for these phenomena range from low-level neural mechanisms to high-level processes that incorporate contextual information or prior knowled...

In many animals, ultraviolet (UV) vision guides navigation, foraging, and communication, but few studies have addressed the contribution of UV vision to color discrimination, or behaviorally assessed UV discrimination thresholds. Here, we tested UV-color vision in an anemonefish ( Amphiprion ocellaris ) using a novel five-channel (RGB-V-UV) LED dis...

Early retinal circuits divide incoming visual information into functionally opposite elementary signals: On and Off, transient and sustained, chromatic and achromatic. Together these signals can yield an efficient representation of the scene for transmission to the brain via the optic nerve. For example, primate On- and Off-parasol circuits are tra...

To camouflage themselves on the seafloor, European cuttlefish Sepia officinalis control the expression of about 30 pattern components to produce a range of body patterns.¹ If each component were under independent control, cuttlefish could produce at least 2³⁰ patterns. To examine how cuttlefish deploy this vast potential, we recorded cuttlefish on...

Animal use color vision in a range of behaviours. Visual performance is limited by thresholds, which are set by noise in photoreceptors and subsequent neural processing. The receptor noise limited (RNL) model of color discrimination is widely used for modelling color vision and accounts well for experimental data from many species. In one of the mo...

An object's colour, brightness and pattern are all influenced by its surroundings, and a number of visual phenomena and "illusions" have been discovered that highlight these often dramatic effects. Explanations for these phenomena range from low-level neural mechanisms to high-level processes that incorporate contextual information or prior knowled...

To conceal themselves on the seafloor European cuttlefish Sepia officinalis express a large repertoire of body patterns. Scenes with 3-D relief are especially challenging because neither is it possible to directly recover visual depth from the 2-D retinal image, nor for the cuttlefish to alter its body shape to resemble nearby objects. Here we char...

The encoding of light increments and decrements by separate On- and Off- systems is a fundamental ingredient of vision, which supports edge detection and makes efficient use of the limited dynamic range of visual neurons¹. Theory predicts that the neural representation of On- and Off-signals should be balanced, including across an animal’s visible...

The encoding of light increments and decrements by separate On- and Off- systems is a fundamental ingredient of vision, which supports the detection of edges in space and time and makes efficient use of limited dynamic range of visual neurons [1]. Theory predicts that the neural representation of On- and Off-signals should be approximately balanced...

To be effective, animal colour signals must attract attention-and therefore need to be conspicuous. To understand the signal function, it is useful to evaluate their conspicuousness to relevant viewers under various environmental conditions, including when visual scenes are cluttered by objects of varying colour. A widely used metric of colour diff...

The Avian retina is far less known than that of mammals such as mouse and macaque, and detailed study is overdue. The chicken (Gallus gallus) has potential as a model, in part because research can build on developmental studies of the eye and nervous system. One can expect differences between bird and mammal retinas simply because whereas most mamm...

Birds and reptiles typically have five spectral types of visual pigment: the rod pigment, plus four cone pigments, which probably gives them tetrachromatic color vision. This system, which was inherited from ancestral vertebrates, can vary under natural selection. Most obvious is the loss of visual pigments in nocturnal lineages including mammals....

Humans and other animals often use colour to recognise objects regardless of their context - as a measure of material properties rather than of their contrast with a background. Most work on visual communication signals is however concerned with colour differences, typically scaled by just noticeable differences (JNDs). Here we move from the prevai...

The jawless fish that were ancestral to all living vertebrates had four spectral cone types that were probably served by chromatic-opponent retinal circuits. Subsequent evolution of photoreceptor spectral sensitivities is documented for many vertebrate lineages, giving insight into the ecological adaptation of color vision. Beyond the photoreceptor...

Cephalopods are the first invertebrate class regulated by the European Union (EU) under Directive 2010/63/EU on the protection of animals used for scientific purposes, which requires prospective assessment of severity of procedures. To assist the scientific community in establishing severity classification for cephalopods, we undertook a web-based...

Colour is commonly regarded as an absolute measure of object properties, but most work on visual communication signals is concerned with colour differences, typically scaled by just noticeable differences (JNDs). Object colour solids represent the colour gamut of reflective materials for an eye. The geometry of colour solids reveals general relatio...

Animal coloration patterns, from zebra stripes to bird egg speckles, are remarkably varied. With research on the perception, function, and evolution of animal patterns growing rapidly, we require a convenient framework for quantifying their diversity, particularly in the contexts of camouflage, mimicry, mate choice, and individual recognition. Idea...

Colour vision mediates ecologically relevant tasks for many animals, such as mate choice, foraging and predator avoidance. However, our understanding of animal colour perception is largely derived from human psychophysics, and behavioural tests of non-human animals are required to understand how colour signals are perceived. Here, we introduce a no...

Vertebrate color vision is evolutionarily ancient. Jawless fish evolved four main spectral types of cone photoreceptor, almost certainly complemented by retinal circuits to process chromatic opponent signals. Subsequent evolution of photoreceptors and visual pigments are now documented for many vertebrate lineages and species, giving insight into e...

Colour vision mediates ecologically relevant tasks for many animals, such as mate choice, foraging and predator avoidance. However, our understanding of animal colour perception is largely derived from human psychophysics, even though animal visual systems differ from our own. Behavioural tests of non-human animals are required to understand how co...

Animal eyes have evolved to process behaviorally important visual information, but how retinas deal with statistical asymmetries in visual space remains poorly understood. Using hyperspectral imaging in the field, in vivo 2-photon imaging of retinal neurons, and anatomy, here we show that larval zebrafish use a highly anisotropic retina to asymmetr...

Computational models that predict the spectral sensitivities of primate cone photoreceptors have focussed only on the spectral, not spatial, dimensions. On the ecologically valid task of foraging for fruit, such models predict the M-cone (“green”) peak spectral sensitivity 10–20 nm further from the L-cone (“red”) sensitivity peak than it is in natu...

Animal eyes evolve to process behaviourally important visual information, but how retinas deal with statistical asymmetries in visual space remains poorly understood. Using hyperspectral imaging in the field, in-vivo 2-photon imaging of retinal neurons and anatomy, here we show that larval zebrafish use a highly anisotropic retina to asymmetrically...

In this quick guide, Darmaillacq and Osorio introduce the reader to the fascinating biology of the cuttlefish.

In living color Animals live in a colorful world, but we rarely stop to think about how this color is produced and perceived, or how it evolved. Cuthill et al. review how color is used for social signals between individual animals and how it affects interactions with parasites, predators, and the physical environment. New approaches are elucidating...

The evolutionary relationship between signals and animal senses has broad significance, with potential consequences for speciation, and for the efficacy and honesty of biological communication. Here we outline current understanding of the diversity of colour vision in two contrasting groups: the phylogenetically conservative birds, and the more var...

Colour patterns displayed by animals frequently comprise multiple elements, including hue, pattern, luminance and texture. Predators' perception of and learning about visual stimuli has important implications for the evolution of animal coloration, including aposematism and mimicry. This study investigated how a coral reef fish, the triggerfish Rhi...

Toxic Heliconius butterflies have yellow hindwing bars that - unlike their closest relatives - reflect ultraviolet (UV) and long wavelength light, and also fluoresce. The pigment in the yellow scales is 3-hydroxy-DL-kynurenine (3-OHK), found also in the hair and scales of a variety of animals. In other butterflies like pierids with color schemes ch...

Toxic Heliconius butterflies have yellow hindwing bars that – unlike their closest relatives – reflect ultraviolet (UV) and long wavelength light, and also fluoresce. The pigment in the yellow scales is 3-hydroxy-DL-kynurenine (3-OHK), found also in the hair and scales of a variety of animals. In other butterflies including pierids, which similarly...

Stubbs and Stubbs present a novel visual mechanism based on chromatic aberration that might allow animals with only one spectral photoreceptor-type to perceive color (1) (see ref. 1 for details about their mechanism). The authors chose cephalopods to showcase their hypothesis and claim that discrepancies between earlier (2, 3) and recent (4, 5) neg...

Color conveys important information for birds in tasks such as foraging and mate choice, but in the natural world color signals can vary substantially, so birds may benefit from generalizing responses to perceptually discriminable colors. Studying color generalization is therefore a way to understand how birds take account of suprathreshold stimulu...

Most butterfly families expand the number of spectrally-distinct photoreceptors in their compound eye by opsin gene duplications together with lateral filter pigments, however most nymphalid genera have limited diversity, with only three or four spectral types of photoreceptor. Here we examine the spatial pattern of opsin expression and photorecept...

Presentation of EU funded Cephalopod research network to inaugural meeting of the BBSRC Animal Welfare Research Network

Colour vision and colour signals are important to aquatic animals, but light scattering and absorption by water distorts spectral stimuli. To investigate the performance of colour vision in water, and to suggest how photoreceptor spectral sensitivities and body colours might evolve for visual communication, we model the effects of changes in viewin...

Humans use shading as a cue to three-dimensional form by combining lowlevel information about light intensity with high-level knowledge about objects and the environment. Here, we examine how cuttlefish Sepia officinalis respond to light and shadow to shade the white square (WS) feature in their body pattern. Cuttlefish display the WS in the presen...

Intracellular recording is a powerful technique used to determine how a single cell may respond to a given stimulus. In vision research, intracellular recording has historically been a common technique used to study sensitivities of individual photoreceptor cells to different light stimuli that is still being used today. However, there remains a de...

This paper is the result of an international initiative and is a first attempt to develop guidelines for the care and welfare of cephalopods (i.e. nautilus, cuttlefish, squid and octopus) following the inclusion of this Class of ∼700 known living invertebrate species in Directive 2010/63/EU. It aims to provide information for investigators, animal...

Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements...

Objective: Scar assessment in the clinical setting is typically impeded by a lack of quantitative data and most systems rely on subjective rating scales which are user dependant and show considerable variability between raters. The growing use of digital photography in medicine suggests a more objective approach to scar evaluation. Our objective w...

Male Lawes's Parotia, a bird of paradise, use the highly directional reflection of the structurally colored, brilliant-silvery occipital feathers in their courtship display. As in other birds, the structural coloration is produced by ordered melanin pigmentation. The barbules of the Parotia's occipital feathers, with thickness ~3 µm, contain 6-7 la...

Cephalopods, such as octopus and squid, can change their coloration in an instant, and even produce moving patterns on their skin. A new study describes these wavelike patterns in a colourful tropical cuttlefish, providing insights into the neural mechanisms that generate them.

Cephalopods are generally regarded as the most intelligent group among the invertebrates. Despite their popularity, relatively little is known about the range and function of their cognitive abilities. This book fills that gap, accentuating the varied and fascinating aspects of cognition across the group. Starting with the brain, learning and memor...

Perceptual organization bridges the gap between the low-level building blocks of incoming sensations and the high-level interpretation of these inputs as meaningful objects, scenes and events in the world. In the visual modality, for instance, the features signaled by the neurons in low-level cortical areas must be combined in order for the high-le...

The compound eyes of mantis shrimps see color in a fundamentally different way from other animals.

Cephalopods have been utilised in neuroscience research for more than 100 years particularly because of their phenotypic plasticity, complex and centralised nervous system, tractability for studies of learning and cellular mechanisms of memory (e.g. long-term potentiation) and anatomical features facilitating physiological studies (e.g. squid giant...

Biological communication signals often combine bright and dark colors, such as yellow and black, but it is unclear why such patterns are effective. The literature on aposematism suggests that high contrast patterns may be easily learnt or innately avoided, whereas studies of sexual signaling refer to their attractiveness or to their cost. Here in e...

The colour vision polymorphism of most New World primates is a model system to study the function of colour vision. Theories for the evolution of primate trichromacy focus on the efficient detection and selection of ripe fruits and young leaves among mature leaves, when trichromats are likely to be better than dichromats. We examined whether colour...

Mimetic wing coloration evolves in butterflies in the context of predator confusion. Unless butterfly eyes have adaptations for discriminating mimetic color variation, mimicry also carries a risk of confusion for the butterflies themselves. Heliconius butterfly eyes, which express recently duplicated ultraviolet (UV) opsins, have such an adaptation...

Survival in the deep sea depends on seeing others without being seen yourself. A recent study examined two switchable camouflage strategies in cephalopods: transparency and dark pigmentation.

Bilateral symmetry is visually salient to diverse animals including birds, but whereas experimental studies typically use bilaterally symmetrical two-dimensional patterns that are viewed approximately fronto-parallel; in nature, animals observe three-dimensional objects from all angles. Many animals and plant structures have a plane of bilateral sy...

Processes in the psychological plane cause us to overlook the fact that in the physical plane all optical effects whatsoever are fundamentally due to differences of colour and brightness, and of light and shade. Cott (1940, p. 3) Accounts of camouflage reflect basic concepts about the relationship between sensory perception and the physical world....

Comparative, ecological, and developmental aspects of visual system design and function - Volume 28 Issue 4 - Barbara L. Finlay, Daniel C. Osorio

It might seem obvious that a camouflaged animal must generally match its background whereas to be conspicuous an organism must differ from the background. However, the image parameters (or statistics) that evaluate the conspicuousness of patterns and textures are seldom well defined, and animal coloration patterns are rarely compared quantitatively...

Evidence that a larval brachiopod has ciliary photoreceptors that are directionally selective, and therefore may function as eyes, bears on an enduring puzzle about photoreceptor evolution in animals.

This chapter and the next focus on measurements of the physical and chemical attributes of potential foods that primates select or reject. The major reason for analysing primate diets in this manner is to understand the basis for their food choice. Observing primates as they feed quickly raises questions in the observer's mind about the possible fo...

The breast-plate plumage of male Lawes' parotia (Parotia lawesii) produces dramatic colour changes when this bird of paradise displays on its forest-floor lek. We show that this effect is achieved not solely by the iridescence--that is an angular-dependent spectral shift of the reflected light--which is inherent in structural coloration, but is bas...

There are three types of account of whether and how primate photoreceptor spectral sensitivities and color vision might have evolved: I) the existing arrangement is sub-optimal, and in particular the spectral separation of the L and M cones reflects their recent evolutionary divergence; II) the spectral sensitivities are optimized for color vision,...

Many animals use the spectral distribution of light to guide behaviour, but whether they have colour vision has been debated for over a century. Our strong subjective experience of colour and the fact that human vision is the paradigm for colour science inevitably raises the question of how we compare with other species. This article outlines four...