PSY 2364 Animal Communication. Midterm. Properties of light. Electromagnetic spectrum. Properties of light. Properties of light 10/4/2017

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1 1/4/217 PSY 2364 Animal Communication Midterm Monday October 9 midterm exam Midterm exam review sheet is posted on the course web page: Electromagnetic spectrum Destroys bonds Increases Increases Absorbed electron energy rotational energy by ions, microwave Different frequencies of light are perceived as different colors. Light varies in intensity (brightness) Light shows wavelength-specific and medium-specific attenuation (selective filtering) One nanometer (nm) = 1 x 1-9 meters Light is directional Light follows the inverse square law Unlike sound, light requires no medium for transmission and in fact travels fastest in a vacuum Light speed varies depending on the medium reflection: light bounces off a surface at the same angle as it strikes the surface refraction: light bends as it travels from one substance to another. diffraction: the slight bending of light as it passes around the edge of an object 1

2 1/4/217 used in animal communication spatial characteristics - variations in shape, size, surface features, color pattern temporal characteristics - changes in pattern of color, surface, color change, apparent size and shape over time Optical communication Specializations of the sender (body structures modified to generate or reflect light for the purposes of communication) Specializations of the receiver (visual system is designed to pick up electromagnetic radiation) Optical communication Ambient light spectra in forest Adaptations to the channel (properties of the signal are selected to maximize the likelihood of unambiguous reception) Ambient light spectra in forest habitats Irradiance Irradiance.1 Forest shade, sunny GREEN.1 Small gap RED W oodland shade, sunny BLUE-GREY Large gap WHITE Forest, woodland shade, or cloudy WHITE.1 Low sun angle PURPLE Batesian mimicry one species has evolved to mimic the warning signals of another species directed at a common predator. Wavelength (nm) W avelength (nm) Wavelength (nm) Monarch Viceroy 2

3 1/4/217 Batesian mimicry: one species has evolved to mimic the warning signals of another species directed at a common predator. Müllerian mimicry: convergence between two or more species to warn predators of their unpalatability. Coral Snake (Micrurus tener) Milk Snake (Lampropeltis triangulum) Phylum: Mollusca Class: Cephalopoda Order: Sepiida Family: Sepiadariidae Genus: Sepioloidea Species: lineolata Anolis carolinensis Green Anole lizard Source: Sepioloidea lineolata Australian cuttlefish Source: Phylum: Mollusca Class: Cephalopoda Order: Sepiida Family: Sepiadariidae Genus: Sepia Species: officinalis Sepia officinalis male squid display zebra stripes only during aggressive conflicts; normal pattern is mottled or blotchy Blue-ringed Octopus (Hapaloclaena lunulata) 1. Warning coloration (blue rings signal danger) 2. Concealing coloration (body colors match coral surroundings) 3. Disruptive coloration (blotches on the skin disguise the outline of the octopus body) 3

4 1/4/217 Hawaiian sepiolid squid (Euprymna scolopes) Camouflage (keeps a "sand coat" on its dorsal surface) Counter-shading (a symbiotic bacteria lives in the sepiolid's light organ to produce a weak light under the body of the animal) Vampire Squid (Vampyroteuthis infernalis) Lives in the dark oxygen minimum layer (6-8 m) For its size, it has the largest eyes of any animal Named for its jet-black skin (but color varies from black to red to purple depending on light conditions) Has photophores; lights all over its body; bioluminescent organs at the tips of each arm Source: Bioluminescence Bioluminescence Deep sea squid, Histioteuthis heteropsis Scyphomedusa, Atolla vanhoeffeni Bioluminescence (lantern fish) Bioluminescence (firefly) Phylum: Arthropoda Class: Insecta Order: Coleoptera Family: Lampyridae Genus: Photinus Species:?? 4

5 1/4/217 Deceptive signaling A female Photuris firefly eats a male Photinus ignitus to obtain defensive compounds called lucibufagins which are distasteful to predators. Femmes Fatales Males are attracted to the species-specific flashing patterns emitted by females. Predatory fireflies of a different species, Photuris, mimic the species-specific flashing pattern of a Photinus firefly to attract and eat the male. Visual systems *** This topic will be covered after the midterm *** Proceedings of the National Academy of Sciences (Sept. 2, 1997, Vol. 94, pp ) Ruby-throated Hummingbird Further reading 5