Question

(4)   What is the handicap hypothesis? How does it explain the existence of costly signals (such as the peacock’s tail)?

(5)        What is ritualization? Describe how ritualization might account for communication signals used to convey defensive attitudes, such as a cat might give when cornered by a dog (arched back, snarling vocalizations, visible teeth).

(6)        What are the three main methods for sound production in animal communication systems? Explain how they work, describe the structures used, and provide an example of each one.

Answer 1

6)

There are several types of animal communication. Three types are mentioned below:

Auditory:

Many animals communicate through vocalization. Vocal communication serves many purposes such as mating rituals, warning calls, conveying location of food sources, and social learning. In a number of species, males perform calls during mating rituals as a form of competition against other males and to signal females. Examples include hammer-headed bats, red deer, humpback whales, elephant seals.

Not all animals this mode as a means of auditory communication. Many arthropods rub specialized body parts together to produce sound. This is known as stridulating. Another means of auditory communication is the vibration of swim bladders in bony fish. The structure of swim bladders and the attached sonic muscles varies greatly across bony fish families, resulting in a wide variety of sounds. Striking body parts together can also produce auditory signals.

Touch

Touch plays an important role in many social interactions. Here are some examples:

1. Fighting: In a fight, touch may be used to challenge an opponent and to coordinate movements during the fight.
2. Mating: Mammals often initiate mating by grooming, stroking or rubbing against each other. This provides the opportunity to apply chemical signals and to assess those excreted by the potential mate. Touch may also announce the intention of the male to mount the female, as when a male kangaroo grabs the tail of a female. During mating, touch stimuli are important for pair positioning, coordination and genital stimulation.

c.     Social integration: Touch is widely used for social integration, a use that is typified by the social grooming of one animal by another. Social grooming has several functions; it removes parasites and debris from the groomed animal, it reaffirms the social bond or hierarchical relationship between the animals, and it gives the groomer an opportunity to examine olfactory cues on the groomed individual, perhaps adding additional ones. This behaviour has been observed in social insects, birds and mammals.

d.    Foraging: Some ant species recruit fellow workers to new food finds by first tapping them with their antennae and forelegs, then leading them to the food source while keeping physical contact. Another example of this is the waggle dance of honey bees.^[23]

e.     Huddling: Prolonged physical contact or huddling also serves social integration. Huddling promotes heat exchange, together with the transfer of olfactory or tactile information. Some organisms live in constant contact in a colony, for example colonial corals. When individuals are linked tightly in this way an entire colony can react on the aversive or alarm movements made by only a few individuals. In several herbivorous insect nymphs and larvae, aggregations where there is prolonged contact play a major role in group coordination. These aggregations may take the form of a procession or a rosette.