Snake genomes encode only two opsins for use in retinal cones, limiting their adaptive flexibility and color vision. Research now shows that, by using alternative opsin alleles, some sea snakes may ...add a third opsin spectral class to their retinas.
Snake genomes encode only two opsins for use in retinal cones, limiting their adaptive flexibility and color vision. Research now shows that by using alternate opsin alleles, some sea snakes may add a third opsin spectral class to their retinas.
Shedding new light on opsin evolution Porter, Megan L; Blasic, Joseph R; Bok, Michael J ...
Proceedings of the Royal Society. B, Biological sciences,
01/2012, Letnik:
279, Številka:
1726
Journal Article
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Opsin proteins are essential molecules in mediating the ability of animals to detect and use light for diverse biological functions. Therefore, understanding the evolutionary history of opsins is key ...to understanding the evolution of light detection and photoreception in animals. As genomic data have appeared and rapidly expanded in quantity, it has become possible to analyse opsins that functionally and histologically are less well characterized, and thus to examine opsin evolution strictly from a genetic perspective. We have incorporated these new data into a large-scale, genome-based analysis of opsin evolution. We use an extensive phylogeny of currently known opsin sequence diversity as a foundation for examining the evolutionary distributions of key functional features within the opsin clade. This new analysis illustrates the lability of opsin protein-expression patterns, site-specific functionality (i.e. counterion position) and G-protein binding interactions. Further, it demonstrates the limitations of current model organisms, and highlights the need for further characterization of many of the opsin sequence groups with unknown function.
Path integration is a robust mechanism that many animals employ to return to specific locations, typically their homes, during navigation. This efficient navigational strategy has never been ...demonstrated in a fully aquatic animal, where sensory cues used for orientation may differ dramatically from those available above the water’s surface. Here, we report that the mantis shrimp, Neogonodactylus oerstedii, uses path integration informed by a hierarchical reliance on the sun, overhead polarization patterns, and idiothetic (internal) orientation cues to return home when foraging, making them the first fully aquatic path-integrating animals yet discovered. We show that mantis shrimp rely on navigational strategies closely resembling those used by insect navigators, opening a new avenue for the investigation of the neural basis of navigation behaviors and the evolution of these strategies in arthropods and potentially other animals as well.
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•Mantis shrimp exhibit direct paths to their home burrows after foraging•Homing is mediated by path integration (vector-based navigation) in mantis shrimp•Mantis shrimp rely on the sun and celestial polarization patterns when orienting•Without celestial information, mantis shrimp use idiothetic (internal) orientation
After finding food, mantis shrimps navigate directly back to the safety of their burrows. Patel and Cronin demonstrate that this aquatic homing behavior is mediated by path integration reliant on celestial and idiothetic compasses, closely resembling strategies used by accomplished terrestrial navigators, such as desert ants.
Animals inhabiting the open ocean often conceal themselves by being highly transparent, but this transparency is compromised by light that is scattered and reflected from the body surface. New ...research shows that some midwater crustaceans use antireflection coatings to enhance their invisibility.
Animals inhabiting the open ocean often conceal themselves by being highly transparent, but this transparency is compromised by light that is scattered and reflected from the body surface. New research shows that some midwater crustaceans use antireflection coatings to enhance their invisibility.
Stomatopod crustaceans, or mantis shrimp, are renowned for their complex visual systems. Their array of 16 types of photoreceptors provides complex color reception, as well as linear and circular ...polarization sensitivity 1–6. The least-understood components of their retina are the UV receptors, of which there are up to six distinct, narrowly tuned spectral types 4. Here we show that in the stomatopod species Neogonodactylus oerstedii, this set of receptors is based on only two visual pigments. Surprisingly, five of the six UV receptor types contain the same visual pigment. The various UV receptors are spectrally tuned by a novel set of four short- and long-pass UV-specific optical filters in the overlying crystalline cones. These filters are composed of various mycosporine-like amino acid (MAA) pigments. Commonly referred to as “nature’s sunscreens,” MAAs are usually employed for UV photoprotection 7, 8, but mantis shrimp uniquely incorporate them into powerful spectral tuning filters, extending and diversifying their preeminently elaborate photoreceptive arsenal.
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•Mantis shrimp have only two UV visual pigments in their retinas•Four types of UV optical filters are found in specific facets of the compound eye•The four UV filters and two visual pigments combine to tune six receptor types•The filters are composed of pigments akin to biological sunscreens
Bok et al. describe a unique system of UV spectral tuning in the eyes of the mantis shrimp Neogonodactylus oerstedii. Specifically, two visual pigments in conjunction with four optical filters, composed of biological sunscreen pigments, produce six spectral types of UV photoreceptors.
Gaze stabilization is an almost ubiquitous animal behaviour, one that is required to see the world clearly and without blur. Stomatopods, however, only fix their eyes on scenes or objects of interest ...occasionally. Almost uniquely among animals they explore their visual environment with a series pitch, yaw and torsional (roll) rotations of their eyes, where each eye may also move largely independently of the other. In this work, we demonstrate that the torsional rotations are used to actively enhance their ability to see the polarization of light. Both Gonodactylus smithii and Odontodactylus scyllarus rotate their eyes to align particular photoreceptors relative to the angle of polarization of a linearly polarized visual stimulus, thereby maximizing the polarization contrast between an object of interest and its background. This is the first documented example of any animal displaying dynamic polarization vision, in which the polarization information is actively maximized through rotational eye movements.
It has been recognized for decades that animals sense light using photoreceptors besides those that are devoted strictly to vision. However, the nature of these receptors, their molecular components, ...their physiological responses, and their biological functions are often obscure. Only recently have researchers begun to learn how critical these non-visual or very simple visual responses are to organismal function. New approaches, including high-throughput molecular genetic techniques, have led to a revolution in our understanding of the evolution, anatomical distribution, physiology, and—in some cases—function of non-visual photoreception in diverse organisms. In the following papers, we bring together specialists from throughout the field to review the current state of knowledge regarding extraocular, non-visual, and simple photoreceptors in a large diversity of organisms ranging from protists through vertebrates and invertebrates.
Patterns and properties of polarized light in air and water Cronin, Thomas W.; Marshall, Justin
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
03/2011, Letnik:
366, Številka:
1565
Journal Article
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Natural sources of light are at best weakly polarized, but polarization of light is common in natural scenes in the atmosphere, on the surface of the Earth, and underwater. We review the current ...state of knowledge concerning how polarization and polarization patterns are formed in nature, emphasizing linearly polarized light. Scattering of sunlight or moonlight in the sky often forms a strongly polarized, stable and predictable pattern used by many animals for orientation and navigation throughout the day, at twilight, and on moonlit nights. By contrast, polarization of light in water, while visible in most directions of view, is generally much weaker. In air, the surfaces of natural objects often reflect partially polarized light, but such reflections are rarer underwater, and multiple-path scattering degrades such polarization within metres. Because polarization in both air and water is produced by scattering, visibility through such media can be enhanced using straightforward polarization-based methods of image recovery, and some living visual systems may use similar methods to improve vision in haze or underwater. Although circularly polarized light is rare in nature, it is produced by the surfaces of some animals, where it may be used in specialized systems of communication.
Arthropods operate in an outrageous diversity of environments. From the deep sea to dense tropical forests, to wide open arctic tundra, they have colonized almost every possible habitat. Within these ...environments, the presence of light is nearly ubiquitous, varying in intensity, wavelength, and polarization. Light provides critical information about the environment, such as time of day or where food sources may be located. Animals take advantage of this prevalent and informative cue to make behavioral choices. However, the types of choices animals face depend greatly on their environments and needs at any given time. In particular, animals that undergo metamorphosis, with arthropods being the prime example, experience dramatic changes in both behavior and ecology, which in turn may require altering the structure and function of sensory systems such as vision. Amphibiotic organisms maintain aquatic lifestyles as juveniles before transitioning to terrestrial lifestyles as adults. However, light behaves differently in water than in air, resulting in distinct aquatic and terrestrial optical environments. Visual changes in response to these optical differences can occur on multiple levels, from corneal structure down to neural organization. In this review, we summarize examples of alterations in the visual systems of amphibiotic larval and adult insects and malacostracan crustaceans, specifically those attributed to environmental differences between metamorphic phases.
•Arthropod visual systems change with different developmental needs in water and air.•Corneal nipple arrays present in adult mayflies, but absent in aquatic juveniles.•Dragonfly nymphs use polarization vision differently than dragonfly adults.•Terrestrial adult crab eyes are spatially adapted to their flat surroundings.•Opsin expression varies between juvenile and adult Palaeoptera.
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