bio 374 study guide

• Umwelt

  The world as it is experienced by a particular organism
• Dazzle camouflage


  A camouflage technique used on ships during World War I and II, consisting of complex patterns of geometric shapes in contrasting colors, intended to confuse enemy ships' rangefinders and gunners by making it difficult to estimate the range, speed, and direction of the camouflaged ship
• Dazzle camouflage on ships


  Not meant to hide the ship but to confuse the enemy about its size, speed, and direction, making it harder for them to accurately target it
• Zebra stripes


  May help deter biting insects, such as horseflies, by disrupting their visual perception and making it difficult for them to land on the zebra's skin
• Dazzle camouflage and zebra stripes


  • Using visual patterns to disrupt perception and make it harder for predators or enemies to target or track the object
• The relationship between equid striping and the prevalence of tabanid flies, which are biting flies known to transmit diseases, has been studied in the context of the evolution of stripes in zebras
• Equid phylogeny


  Shows the relationship between equid striping and the prevalence of tabanid flies
• The presence of stripes in zebras may disrupt the visual cues that tabanid flies use to locate hosts, making it harder for them to land on the zebra's skin and feed, which could reduce the risk of disease transmission and discomfort for the zebra
• The evidence from the equid phylogeny informs current thinking about the evolution of stripes in zebras by suggesting that the striping pattern may have evolved as an adaptation to the presence of tabanid flies
• Predator psychology hypothesis


  Eyespots mimic the eyes of larger animals, such as predators or other threatening creatures, triggering a psychological response in the predator, such as fear or intimidation, causing the predator to hesitate or abandon its attack
• The available evidence generally supports the predator psychology hypothesis, although the exact mechanisms and effectiveness may vary depending on the species and context
• Studies have shown that predators, such as birds and lizards, are more likely to attack prey items that lack eyespots or have eyespots obscured, compared to those with prominent eyespots
• Experiments using artificial prey with and without eyespots have demonstrated that predators are less likely to attack prey with eyespots
• There are also alternative hypotheses that suggest eyespots may serve other functions, such as deflecting attacks away from vital body parts or disrupting the predator's ability to target the prey
• Flycatchers evaluate the suitability of potential nest sites

  Based on factors such as the presence of predators, the availability of food resources, the proximity to suitable foraging areas, and the quality of the nesting substrate
• Early-arriving flycatchers


  May prioritize factors such as competition for nest sites and the availability of high-quality territories, and rely more on environmental cues to assess nest site suitability
• Late-arriving flycatchers


  May have fewer options for nest sites and may be more focused on quickly finding a suitable location, relying more on direct assessments, such as inspecting potential nest cavities or observing the presence of predators, to determine suitability
• Signal-to-noise ratio (SNR)


  A measure of how much stronger the signal is compared to the noise
• Response


  The output of the system being studied, which can vary depending on the SNR
• As the SNR increases (signal becomes stronger relative to noise), the response of the system being studied would generally be expected to increase or become more pronounced
• There may be a threshold SNR below which the response is not detectable or significant
• Olfaction

  The sense of smell, primarily detected by the olfactory system located in the nasal cavity
• Taste


  Detected by taste buds located on the tongue and other parts of the mouth, can detect five basic tastes: sweet, sour, salty, bitter, and umami (savory)
• Differences between olfaction and taste

  • Olfaction involves specialized receptors in the nasal epithelium that detect specific odor molecules, while taste involves receptors located on taste buds that detect different taste molecules
  • Olfaction is important for detecting and identifying volatile chemicals in the environment, while taste helps to evaluate the chemical composition of foods and beverages
  • Olfaction contributes significantly to the overall perception of flavor, while taste provides a more limited range of sensory information
• Odor travel


  Odor molecules are emitted from a source and spread out, creating a concentration gradient that organisms can use to track the odor to its source
• Factors influencing odor travel and tracking

  • Air currents can carry odor molecules over long distances and affect the dispersion of the odor
  • Diffusion of odor molecules creates a gradient of decreasing concentration away from the source
  • Organisms may exhibit specific behaviors, such as zigzagging flight patterns, to sample the air and determine the direction of the odor gradient
  • Environmental factors, such as obstacles or barriers, can influence how odors travel and how organisms track them
• Pheromones


  Chemical substances released by an animal that trigger a specific response in other members of the same species, such as mating behavior, territorial marking, aggregation, alarm signals, and trail following
• Signature mixes


  Unique chemical blends that are specific to individual animals or groups of animals, used to convey information about identity, kinship, and group membership
• Differences between pheromones and signature mixes

  • Pheromones are used to communicate information about reproductive status, social status, and other important aspects of an animal's behavior, while signature mixes are used to recognize and identify individuals within a group, establish social bonds, and maintain group cohesion
• Insect olfactory sensillum

  Hair-like structures on the antennae of insects that contain sensory neurons surrounded by support cells, with odor molecules entering through pores and binding to odorant receptors on the dendrites of the sensory neurons
• Vertebrate olfactory epithelium

  Located in the nasal cavity, contains olfactory receptor neurons (ORNs) with cilia that extend into the mucus layer, where odorant receptors are located to detect odor molecules
• Electroreception, the ability to detect electric fields, is most likely to be found in ecological conditions where organisms can benefit from detecting bioelectric signals or navigating in environments where visual or olfactory cues are limited, such as dark or murky environments, nocturnal conditions, and aquatic environments
• Olfactory nerve


  Nerve that sends electrical signals to the brain
• Olfactory epithelium


  • Capable of regenerating throughout life
  • Contains support cells that provide structural support and help maintain the mucus layer
• Ecological conditions where electroreception is most likely to be found

  1. Dark or murky environments

  2. Nocturnal or crepuscular activity

  3. Sediment-rich environments

  4. Detecting prey or predators

  5. Communication and navigation
• Experiment that established small-spotted catsharks use electroreception to find prey


  1. Flatfish buried in sand - shark orients to fish

  2. Flatfish buried in sand, but surrounded by agar chamber that blocks mechanical and some olfactory cues - shark orients to fish

  3. Flatfish chopped up into pieces and buried in sand in agar chamber that blocks mechanical and some olfactory cues - shark orients to flow-through

  4. Flatfish buried in sand, but surrounded by electrically insulated agar chamber that blocks mechanical, electrical, and olfactory cues - shark does not orient

  5. Two electrodes buried in sand - shark orients to electrodes

  6. Electrode buried in sand, flatfish chopped up and placed on surface of sand - shark orients to electrode
• Passive electroreception


  Detection of electric fields generated by other organisms or environmental sources without actively emitting electric signals
• Active electroreception


  Generation and detection of electric signals by an organism
• Active electroreception


  • Animals can generate weak electric fields themselves and then detect distortions or changes in these fields caused by nearby objects or organisms
• Information gained from active electroreception


  • Object detection
  • Prey detection
  • Communication
  • Navigation
  • Social interactions