Lecture D2 (2025-09-25): Modes of Communication

In this lecture, we discuss the major modes of communication and spend some time discussing how animals use these different modalities to signal each other. This lecture focuses on a variety of communication mechanisms across the modalities and how they might have been co-opted from existing mechanisms that were adapted for other functions. After discussing tactile, chemical, acoustic, visual, and electric communication, we close with a brief discussion of multi-modal signals.

Topic highlights:

• the four major communication modalities (plus electricity)
• exploration of tandem running as a behavior employing simultaneous bi-directional communication between ants
  • both tactile and olfactory communication
• examples of olfactory/chemical communication
  • discussion of the origins of the "tandem calling" signal as co-option of the poison/venom gland in the sting
  • definition of the semiochemicals: pheromones, allomones, kairomones, and synonomes
  • categories of different pheromones: volatile and headspace, non-volatile and contact
  • cuticular hydrocarbons (CHC's) on insects and their evolution for desiccation mitigation and then communication
• primer and releaser signals
• examples of acoustic communication
  • amplitude and frequency of sound waves
    • complex sound waves are viewed as sums of many different frequencies of simple oscillating sound waves
    • perceived amplitude of each frequency component of a signal varies by frequency
  • stridulation (and scrapers and files)
  • tymbal
  • semantic communication in monkey alarm calls
  • danger of noise corruption in acoustic signals
• examples of visual communication
  • use of color and bioluminescence for both signaling and deception
  • use of countershading and counter-illumination for concealment
• examples of electric communication in weakly electric fish
  • electrolocation and communication
  • comparison to evolution of the poison gland for communication
• multi-modal communication (and redundant signals as a subset of multi-modal communication)

Important terms: communication mode/modality, antennae, semiochemical, pheromone, allomone, kairomone, synomone, volatile pheromones, headspace, contact/non-volatile pheromones, cuticular hydrocarbon (CHC), primer, releaser, fixed action pattern, stridulation, frequency, amplitude, tymbal/timbal, bioluminescence, countershading, counter-illumination, multi-modal communication