Illustrations

Figure 1.1	Cloisonné vase with sunfish, made using gold wire and enamels.    2
Figure 1.2	Female cardinal evaluating a male in sunlight against natural foliage.    4
Figure 1.3	Fossilized compound eyes of two trilobite species.    5
Figure 1.4	A view of visual evolution as a punctuate process, advancing through a series of steps that represent significant leaps in visual capabilities.    6
Figure 1.5	Evolution of modern opsins.    7
Figure 2.1	The elephant hawkmoth (Deilephila elpenor) as viewed during late twilight and on a moonless night, showing the extreme chromatic changes that can occur within 30 minutes.    11
Figure 2.2	The electromagnetic spectrum.    12
Figure 2.3	Daylight spectrum binned by equal wavelength intervals and by equal frequency intervals.    14
Figure 2.4	The three most common light measurements: vector irradiance, radiance, and scalar irradiance.    15
Figure 2.5	Solar irradiance outside the atmosphere and at the Earth’s surface.    16
Figure 2.6	Fraction of irradiance at Earth’s surface near noon due to skylight alone.    17
Figure 2.7	Downwelling vector irradiance and scalar irradiance (at 560 nm) as a function of solar elevation.    18
Figure 2.8	Illuminance due to moon and sun at various times of day.    19
Figure 2.9	Irradiance on a North Carolina beach when sun is 10.6° below the horizon (late nautical twilight).    19
Figure 2.10	Landscape photographed under full moonlight and spectral reflectance of the moon.    20
Figure 2.11	Lunar irradiance (normalized to 1 for a full moon) and fraction of moon illuminated as a function of degrees from full moon.    21
Figure 2.12	Landscape under starlight and reconstructed downwelling irradiance spectrum of moonless night sky.    22
Figure 2.13	A green aurora combined with an unusually intense red aurora.    23
Figure 2.14	Light pollution in New York City and downwelling irradiance spectrum dominated by light pollution on a cloudy night at Jamaica Pond in Boston, MA.    24
Figure 2.15	Human-based chromaticities (i.e., perceived color) of daylight, sunset, twilight, and nocturnal irradiances.    25
Figure 2.16	Spectra of downwelling irradiance in a forest near Baltimore, MD.    26
Figure 2.17	The first two principal components (statistical measures of major sources of variation) of the spectra shown in figure 2.16.    26
Figure 2.18	The absorption and scattering coefficients of the clearest natural waters, along with their sum.    27
Figure 2.19	Downwelling irradiance in the equatorial Pacific modeled from vertical profiles of absorption, scattering, and chlorophyll concentration.    28
Figure 2.20	Radiance as a function of viewing angle and depth in equatorial Pacific waters with the sun 45° above the horizon.    30
Figure 2.21	Peak wavelength versus emission width for the light emissions from deep-sea benthic and mesopelagic species.    33
Figure 2.22	Examples of the various uses of bioluminescence.    34
Figure 2.23	Ambient light images of a deep-sea volcanic vent at nine visible and near-infrared wavelengths imaged by the ALISS camera system. Spectrum of emitted light at four locations within vent compared to the spectrum of a blackbody radiator at the vent temperature.    35
Figure 3.1	Structures of vertebrate and invertebrate visual pigments viewed from the plane of the plasma membranes of photoreceptor cells.    38
Figure 3.2	Structure of retinal, the most common chromophore found in visual pigments.    39
Figure 3.3	Typical absorption spectra of visual pigment molecules normalized to the same peak value.    40
Figure 3.4	The four types of chromophores known to be used in visual pigments.    41
Figure 3.5	Spectral effects on a visual pigment of changing from a retinal chromophore to a 3-dehydroretinal chromophore and how the wavelength of maximum absorption changes when the same opsin is bound to an A1 or an A2 chromophore.    42
Figure 3.6	Schematic illustration of dichroism in visual pigments.    43
Figure 3.7	Seemingly unimportant changes in absorbance can produce major effects on how a photoreceptor cell actually absorbs light.    45
Figure 3.8	Electron micrographs to show the arrangements of photoreceptor membranes in a vertebrate rod cell and an invertebrate rhabdom.    47
Figure 3.9	The structure of typical vertebrate photoreceptors illustrated diagrammatically, showing the inner and outer segments connected by a ciliary neck.    49
Figure 3.10	Structure of typical microvillar, or rhabdomeric, photoreceptors found in many invertebrates.    50
Figure 3.11	Optical modifications of vertebrate photoreceptors for specialized tasks.    51
Figure 3.12	Filters in vertebrate cones and the spectra of light they transmit.    52
Figure 3.13	Filters in invertebrate photoreceptors.    53
Figure 3.14	Photographs of invertebrate photoreceptor filter pigments and characteristic absorption spectra of the pigments.    54
Figure 3.15	Spectral sensitivity augmentation by sensitizing pigments.    55
Figure 3.16	Histograms to show values of λmax of visual pigments in photoreceptors of deep-sea animals.    57
Figure 3.17	Visual pigments in rod photoreceptors of marine mammals that reach different maximum depths when foraging, compared with a terrestrial mammal (the cow).    58
Figure 3.18	Irradiance spectra in typical habitats occupied by animals and an analysis of how photon capture in each irradiance condition changes with visual pigment λmax.    59
Figure 3.19	Color images of natural scenes in a temperate forest and a tropical coral reef along with dichromatic images of the same scenes using various wavelength pairs.    62
Figure 3.20	The cone array in the retina of the chinchilla (Chinchilla lanigera).    63
Figure 3.21	Developmental changes in visual pigments that occur during development of the hydrothermal vent crab Bythograea thermydron. 65
Figure 4.1	The pigment-pit eye of the arc clam Anadara notabilis.    67
Figure 4.2	A schematic camera eye viewing a visual scene (the trunk and bark of a eucalyptus tree).    69
Figure 4.3	Spatial resolution and light level.    70
Figure 4.4	Quantum events in photoreceptors.    72
Figure 4.5	Diffraction.    79
Figure 4.6	Optical aberrations.    81
Figure 4.7	Underfocused eyes.    83
Figure 4.8	Solutions for optical cross talk in the retina.    85
Figure 4.9	The modulation transfer function.    87
Figure 4.10	The modulation transfer function of an eye.    89
Figure 5.1	The pinhole eye of Nautilus.    93
Figure 5.2	The concave mirror eye of the scallop Pecten.    95
Figure 5.3	Camera eyes.    98
Figure 5.4	Amphibious vision in camera eyes.    101
Figure 5.5	The dark-adapted and light-adapted pupil of the nocturnal helmet gecko, Tarentola chazaliae.    103
Figure 5.6	The camera eyes of the octopus and the cod (Gadus morhua).    104
Figure 5.7	Ommatidia.    107
Figure 5.8	The two broad subtypes of compound eyes.    108
Figure 5.9	Focal and afocal optics in apposition compound eyes.    109
Figure 5.10	The three different types of superposition optics found in the Arthropoda, showing the paths of incident light rays focused by the cornea into the crystalline cones.    111
Figure 5.11	The refracting superposition eyes of the nocturnal dung beetle Onitis aygulus, which consist of a smaller dorsal eye and a larger ventral eye that are separated by a chitinous canthus on each side of the head.    112
Figure 5.12	Graded refractive index optics in the refracting superposition eyes of the nocturnal dung beetle Onitis aygulus. 113
Figure 5.13	Theoretical retinal image quality in the refracting superposition eyes of three species of dung beetles from the genus Onitis—the diurnal O. westermanni, the crepuscular O. alexis, and the nocturnal O. aygulus. The rhabdoms of dung beetles are flower shaped in cross section.    115
Figure 6.1	The definition of the interreceptor angle Δφ in camera eyes and the interommatidial angle Δφ in compound eyes.    118
Figure 6.2	The densities of rods and cones in the human retina as a function of distance (eccentricity) from the fovea.    120
Figure 6.3	The retinal ganglion cells, the sampling stations of the vertebrate retina.    122
Figure 6.4	The eyes of jumping spiders.    124
Figure 6.5	Negative lenses in camera eyes.    126
Figure 6.6	Acute zones and bright zones in apposition compound eyes.    128
Figure 6.7	An acute zone in the retina of a superposition compound eye.    130
Figure 6.8	Double eyes and sexual dimorphism in insects.    133
Figure 6.9	Optical sexual dimorphism in the apposition eyes of flies.    134
Figure 6.10	Neural sexual dimorphism in the apposition eyes of flies.    136
Figure 6.11	The dorsal acute zone of dragonflies.    138
Figure 6.12	The visual fields of predators and prey.    139
Figure 6.13	Horizontal acute zones in compound eyes.    140
Figure 6.14	Habitat-related ganglion cell topographies in terrestrial mammals.    141
Figure 6.15	Vision through Snel’s window, where the 180° view of the world above the water surface is compressed due to refraction into a 97.6°-wide cone below the water surface.    143
Figure 6.16	Deep-sea eye structure and the changing nature of visual scenes with depth.    144
Figure 7.1	An apple tree image optimized for human color vision using our three-color (RGB) printing process and with the color stripped from the image.    147
Figure 7.2	The varied spectral sensitivities of vertebrates and invertebrates.    148
Figure 7.3	The colors of natural objects and their perception by the color-vision systems of animals.    150
Figure 7.4	Histogram of the distribution of known spectral sensitivity peaks in 40 hymenopteran species.    153
Figure 7.5	The spectral sensitivities of tetrachromatic birds and fish.    154
Figure 7.6	The spectral sensitivities and resulting trichromatic color space of adult lungfish modeled without and with oil droplets.    155
Figure 7.7	Bee color vision and flower colors, reef fish color vision and fish colors.    158
Figure 7.8	UV patterns and contrast made visible to the human visual system by photography through UV filters.    160
Figure 7.9	λmax positions of cones and rods in marine fish arranged by habitat.    161
Figure 7.10	The spectral sensitivities of four species of reef fish from the same photic microhabitat.    162
Figure 7.11	Color vision in cardinal fish (Family Apogonidae).    163
Figure 7.12	African cichlid eyes collectively contain all seven cone opsins known in fish.    165
Figure 7.13	The offset hypothesis.    166
Figure 7.14	The barracuda Sphyraena helleri is associated with reefs and lives in a shallow photic habitat that could accommodate more than its known two spectral sensitivities.    167
Figure 7.15	Crustacean spectral sensitivities.    169
Figure 7.16	Spectral tuning with depth both between and within stomatopod species.    171
Figure 7.17	Behaviorally determined wavelength discrimination functions (Δλ) in stomatopods (Haptosquilla trispinosa) compared to various animals: human, goldfish, butterfly, honeybee.    172
Figure 7.18	Regionalization of spectral sensitivities in the eyes of vertebrates and invertebrates.    174
Figure 7.19	Vision in the archerfish (Toxoides chatareus), a fish that spits at prey located above the water surface.    175
Figure 7.20	The hypothetical origin of color vision as a way to remove caustic flicker produced by ripples in water in shallow Cambrian aquatic habitats.    176
Figure 8.1	Two representations of various states of polarized light starting as a nonpolarized light beam and its polarization through a linear polarizing filter and then conversion to circular polarization through a quarter-wave retarder.    179
Figure 8.2	Sources of linearly polarized light in nature.    181
Figure 8.3	Polarized light in air and water.    182
Figure 8.4	Sources of elliptically polarized light in nature.    184
Figure 8.5	The orientation of visual pigment chromophores and resulting dichroism within photoreceptor membrane.    185
Figure 8.6	Terrestrial and aquatic scenes showing differences in polarization information.    187
Figure 8.7	Drassodes cupreus and its polarization-sensitive posteromedial eyes.    188
Figure 8.8	Ommatidia in the dorsal rim area and main eye of various insects.    189
Figure 8.9	Rhabdom construction in crustaceans and cephalopods.    190
Figure 8.10	Circular polarization detection in stomatopods.    192
Figure 8.11	Responses of polarization receptors.    194
Figure 8.12	Polarization processing.    195
Figure 8.13	Polarization vision in the backswimmer Notonecta glauca.    196
Figure 8.14	Organization and function of dorsal rim area ommatidia.    197
Figure 8.15	Organization of polarization information coming from the compound eyes of the locust, Schistocerca gregaria.    198
Figure 8.16	Behavioral orientation and navigation under celestial e-vector patterns or artificial polarizers.    199
Figure 8.17	Responses of animals with polarization vision to virtual looming stimuli.    202
Figure 8.18	Choices of female Australian orchard swallowtail butterflies, Papilio aegeus, viewing color/polarization targets.    203
Figure 8.19	Linear polarization patterns likely to be involved in signaling.    204
Figure 9.1	Underwater photograph taken at the Great Barrier Reef off the coast of Australia and fog on a pond in Durham, NC.    207
Figure 9.2	A beam of light is both absorbed and scattered as it passes through an attenuating medium such as water or fog.    208
Figure 9.3	The scattering and beam attenuation coefficients at the surface and at 100 m depth in clear oceanic water.    210
Figure 9.4	A mackerel (Grammatorcynus bicarinatus) in water. The object, path, and total radiance for an object that is twice as bright as the background viewed horizontally in oceanic water at 480 nm.    212
Figure 9.5	The GretagMacbeth Colorchecker modeled to show how it would appear if viewed horizontally in clear oceanic water at a depth 5 m and at various viewing distances.    216
Figure 9.6	The minimum detectable radiance difference as a function of the adapting illumination in humans.    217
Figure 9.7	The contrast threshold as a function of the adapting illumination in humans.    218
Figure 9.8	The contrast threshold as a function of spatial frequency for a number of vertebrate species.    219
Figure 9.9	Historical room in Bäckaskog castle in Kristianstad, Sweden.    219
Figure 9.10	Sighting distances depend on the product of two factors.    221
Figure 9.11	The second factor affecting sighting distance (1/[c − KL cos θ]) is given in meters as a function of wavelength and viewing angle (θ) for oceanic water at 100-m depth.    222
Figure 9.12	The inherent contrast of an underwater object is greatly affected by wavelength.    223
Figure 9.13	Sighting distances for a large object that diffusely reflects 50% of the light that strikes it as a function of depth, wavelength, and viewing angle.    224
Figure 9.14	Underwater scene photographed through vertically oriented and horizontally oriented polarizers. Image also shown after polarization-based dehazing.    226
Figure 9.15	The scattering coefficients in a standard atmosphere as a function of altitude.    228
Figure 9.16	A case in which the only light that reaches the viewer’s eye is light that has never been scattered. Another case in which some of the light that reaches the viewer’s eye has been scattered more than once. An underwater scene where multiple scattering is just beginning to be significant.    230
Figure 10.1	Representations of flow fields projected onto a retina (these vectors also could represent the motions of objects in visual space).    234
Figure 10.2	A diagrammatic view of a Reichardt detector sensitive to motion in the direction of the large open arrow. An apparatus often used to study motion perception in flying insects.    236
Figure 10.3	Wide-field cells in the lobula plate of Drosophila. 238
Figure 10.4	Modeling wide-field sensing in flies.    238
Figure 10.5	Schematic showing typical responses of a motion-sensitive ganglion cell.    239
Figure 10.6	Motion sensing in vertebrate retinas.    239
Figure 10.7	Eye movements in mantis shrimp (photographs).    241
Figure 10.8	Eye movements in mantis shrimp (graphs).    242
Figure 10.9	Examples of optokinesis in aquatic animals.    245
Figure 10.10	Ocular fixation movements in action.    246
Figure 10.11	Tracking and chasing.    249
Figure 10.12	Tracking in praying mantis.    250
Figure 10.13	Flight room at the Janelia Farm research center in Virginia for study of the neurobiology underlying motion sensing and flight control in dragonflies.    252
Figure 10.14	Aerial tracking by a peregrine falcon at a cliff site in Colorado, showing spiral flight paths made to intercept prey over a lake.    253
Figure 10.15	Scanning behavior in larvae of the water beetle Thermonectes marmorata.    254
Figure 10.16	A flight tunnel used in experiments on motion vision of flying honeybees.    257
Figure 10.17	Schematic drawing of the apparatus used to test the abilities of honeybees to judge relative heights of “flowers” using motion vision.    258
Figure 10.18	Head movements of a foraging whooping crane searching for food on the ground.    259
Figure 10.19	Responses of a dragonfly interneuron that responds to looming stimuli, signaling estimated time to contact.    260
Figure 11.1	Nocturnal color vision in insects.    265
Figure 11.2	Nocturnal navigation using celestial cues.    267
Figure 11.3	Nocturnal homing in arthropods.    268
Figure 11.4	Visual acuity in nocturnal birds and mammals measured behaviorally as a function of luminance.    272
Figure 11.5	Optical adaptations for nocturnal vision in camera eyes.    274
Figure 11.6	Fresh head of a giant squid (likely from the genus Architeuthis).    275
Figure 11.7	Tubular eyes in deep-sea fish.    276
Figure 11.8	Rostral aphakic gaps in the eyes of deep-sea fish.    278
Figure 11.9	The tapetum lucidum and the eye glow of animal eyes.    279
Figure 11.10	Retinal specializations for dim-light vision in vertebrates.    280
Figure 11.11	The banked retina of the nocturnal oilbird and deep-sea fish.    281
Figure 11.12	Specializations for dim-light vision in compound eyes.    284
Figure 11.13	Spatial summation in nocturnal bees.    287
Figure 12.1	A sandhopper, Talitrus saltator, on a sandy beach in Italy.    290
Figure 12.2	Two photographs of deep-sea fish with bioluminescent lures and flashlight fish with lids open and closed.    292
Figure 12.3	The third zoeal stage of the larva of the crab Rhithropanopeus harrisi and graphs showing phototaxis to various wavelengths of light by early-stage zoea larvae and descent by these larvae on a sudden decrease in light intensity in clean water and in water that had contained ctenophores, a predator on larvae.    293
Figure 12.4	Genetic inheritance of orientation in different populations of Talitrus saltator on the west coast of Italy.    294
Figure 12.5	Orientations of ball-rolling dung beetles, Scarabaeus nigroaeneus, in the field, South Africa.    295
Figure 12.6	The orientations during flight outdoors near noon of intact and antennaless monarch butterflies, Danaus plexippus, before and after being subjected to a 6-hour phase delay in the light:dark cycle.    297
Figure 12.7	“Turn-back-and-look behavior” in foraging honeybees, Apis mellifera. 299
Figure 12.8	Nest orientation in the solitary wasp Cerceri rybyensis on leaving its nest hole.    300
Figure 12.9	Landmark learning in honeybees.    300
Figure 12.10	The “snapshot model” of landmark orientation in honeybees.    301
Figure 12.11	Nocturnal learning and recognition of landmarks by the Panamanian bee, Megalopta genalis.    302
Figure 12.12	Landmark orientation in the desert ant Cataglyphis bicolor, an individual of which is shown at the top left.    303
Figure 12.13	Place cells in the rat, Rattus norvegicus. 304
Figure 12.14	Landmark learning and use in the ant, Formica rufa.    306
Figure 12.15	Landmark use in the Australian desert ant, Melophorus bagoti. 307
Figure 12.16	Images of the Panamanian rainforest canopy taken at intervals along a trail through the forest.    308
Figure 12.17	Seaward orientation by hatchling loggerhead turtles, Caretta caretta. 309
Figure 12.18	Visual odometry in honeybees.    311
Figure 13.1	Silhouette of the cookie-cutter shark (Isistius brasiliensis) as viewed from below without counterillumination and the silhouette of the same animal with its many small ventral photophores turned on.    314
Figure 13.2	Animals in featureless environments, such as the snub-nosed dart (Trachinotus blochii), tend to employ strategies that reduce contrast and thus detectability. In contrast, animals in complex environments, such as the giant Australian cuttlefish (Sepia apama), tend to employ strategies that reduce recognition, usually via color patterns and in some cases texture.    315
Figure 13.3	The four primary mechanisms of camouflage and signaling are based on the four ways in which light can interact with matter.    316
Figure 13.4	The barreleye spookfish (Opisthoproctus soleatus), one of many deep-sea fish with eyes that look directly upward, presumably to catch the most light and thus improve vision.    317
Figure 13.5	The euphausiid shrimp, Meganyctiphanes norvegica, and the deep-sea hatchetfish, Argyropelecus aculeatus.    318
Figure 13.6	Various established and hypothesized functions of bioluminescence in marine species.    320
Figure 13.7	Fireflies at night. Note that the dark and simple background makes the signal easy to discern.    321
Figure 13.8	The bioluminescent courtship displays of various species of ostracod.    322
Figure 13.9	The coronate medusa Atolla wyvillei and one moment in the animal’s bioluminescent “pinwheel” display.    322
Figure 13.10	Examples of transparent animals.    324
Figure 13.11	Transparency and pelagic existence mapped onto a phylogeny of the major phyla in the Animalia.    325
Figure 13.12	The bolitaenid octopus, Japetella heathi in its transparent and pigmented forms.    327
Figure 13.13	The pelagic tunicate, Salpa cylindrical, and its transmittance of visible and ultraviolet radiation.    328
Figure 13.14	Selected images of transparent plankton viewed between parallel polarizing filters and crossed polarizers.    329
Figure 13.15	The anemone cleaner shrimp, Periclimenes holthuisi. 330
Figure 13.16	Strongly colored lures on the tips of the feeding tentacles of the siphonophore Resomia ornicephala, an example of aggressive mimicry.    330
Figure 13.17	Reflection from vertical mirrors underwater can look just like the view behind the animal because the light field is symmetric around the vertical axis. A vertical mirror photographed at 10-m depth shows that mirroring also works as crypsis in shallow waters if the sun is high in the sky.    331
Figure 13.18	The snub-nosed dart (Trachinotus blochii) well camouflaged by reflection from its silvery sides and a moment later, after it had tilted slightly, reflecting downwelling light to the viewer and becoming more visible.    332
Figure 13.19	The common bleak fish, Alburnus alburnus and a cross section of the fish showing the vertical orientation of most of the reflecting structures in the scales.    332
Figure 13.20	Intensity image of the bluefin trevally (Caranx melampygus), showing that it matches the background light well. Another image of the same fish shows the degree of polarization of the fish and the background.    334
Figure 13.21	Structural colors in the plumage of the male of the Indian peafowl (Pavo cristatus).    334
Figure 13.22	The coloration of oceanic species as a function of depth.    336
Figure 13.23	The red-eye gaper (Chaunax stigmaeus) photographed at depth under broad-spectrum lighting.    337
Figure 13.24	Mexican blind cavefish Astyanax mexicanus, one from a surface-dwelling population and one from a cave-dwelling population.    338
Figure 13.25	Twelve color morphs of the strawberry poison dart frog (Dendrobates pumilio), all from the Bocas del Toro region of Panama.    339
Figure 13.26	Maxwell triangle for a honeybee (Apis mellifera) viewing a violet flower and a blue flower through fog.    341
Figure 13.27	The dottyback (Pseudochromis paccagnellae) photographed at depth on a coral reef and a head of a male three-spined stickle-back (Gasterosteus aculeatus) photographed in the greenish water that it usually inhabits.    341
Figure 13.28	The GretagMacbeth ColorChecker™ as it appears in daylight and as it would appear if it were photographed at 40-m depth in clear ocean water or if it were photographed at 20-m depth in green coastal water.    342
Figure 13.29	Full-color image of two surf parrotfish (Scarus rivulatus), a lined butterflyfish (Chaetodon lienolatus), a minifin parrotfish (Scarus altipinnis), and the head of a hussar (Lutjanus adetii). The same image as viewed by an animal with only a medium-wavelength visual pigment, (the patterns on the three parrotfish are no longer visible) and as viewed by an animal with only a long-wavelength visual pigment, which increases the achromatic contrast of the details on the parrotfish. A dichromatic viewer can distinguish more than a monochromat.    343