For Students of Biological Sciences

1. B Y
N A V E E D A K H T A R
A S S I S T A N T P R O F E S S O R O F Z O O L O G Y
Animal Communication

2. What is communication?
 Animal communication is the passage of information b/w two
animals
 The animal which sends is called signaler and the animal
that receives signal is called receiver.
 It benefits the signaler or an average to both partner.
 The transfer of information from a signaler to a receiver—in
order to better understand animal behavior.
 Animal communication is also known as Biological
communication
 A stereotyped sequenced of behaviors that has a signaling
function is called Display.
 he study of animal communication is called Zoosemiotics
 The classical ethological view of communication was
developed by Niko Tinbergen.

3. Animal Need of Communication
 .

6. Channels of Communication in Animals
 The pathway linking a signaler and the receiver of
the signal is known as a channel.
 The term channel of communication is used to
describe the various sensory modalities that are
utilized by animals to facilitate effective
communication
 Some such as the electrical sense are relatively rarely
used because they can only operate in one specific
environment
 These are the visual, auditory, chemical and
mechanical channels

7.  Each of these channels presents advantages and
disadvantages to the user, and these may vary from
environment to environment.
 For this reason individuals may rely upon a
combination of them

8. 1. The Visual Channel (Vision)

13.  Facial expressions are also used to convey
information in some species. For instance, what is
known as the fear grin—shown on the face of the
young chimpanzee below—signals submission. This
expression is used by young chimpanzees when
approaching a dominant male in their troop to
indicate they accept the male's dominance.

18.  Sound signals have several advantages.
 They can be transmitted over long distances, especially in
water. Although sound is transmitted more slowly than
light, it still can be a rapid means of sending a message,
particularly at close range
 For example, mammals use their larynx and birds use
their syrinx to produce sound.
 The anatomical structure and location of these organs are
different, but both allow production of complex sounds.
 Crickets, for example, produce sound by opening and
closing their wings.

19.  Some animals make sounds that humans cannot
hear. For example, several groups of mammals,
including cetaceans, bats, and rodents, produce and
detect ultrasounds as part of echolocation
 Ultrasounds are sounds whose frequencies are above
those audible to humans, which means frequencies
greater than about 20 kHz
 Human hearing also has a lower limit: we typically
cannot hear sounds whose frequencies are less than
about 20 Hz, so sounds below this limit are called
infrasound.

20. 3. CHEMICAL SENSES

22.  The advantages of chemical communication are not as
immediately apparent as those offered by the visual and
acoustic channels.
 To be effective the molecules that make up a chemical
signal need to move from the sender to the receiver.
 In some cases this is achieved by the sender physically
placing the signal onto the receiver, or by the receiver
moving to a deposited signal to pick it up. More often it
involves the movement of the chemical through air or
water by the process of diffusion.

23.  Some species of amphibians, reptiles, and mammals have
a vomeronasal (or Jacobson’s) organ that is
important in chemical communication between mates,
parents and offspring, and rivals.
 t is anatomically separate from other chemosensory
structures, and its neural wiring goes to brain regions
different from those associated with the main olfactory
system
 The vomeronasal organ is located in the roof of the
mouth or between the nasal cavity and the mouth, so
communicative chemicals must reach it through the
nose, mouth, or both. B

24.  Pheromones:
 Chemicals produced to convey information to other members of the same
species are called pheromones. Some of these, releaser pheromones, have
an immediate effect on the recipient’s behavior.
 A good example of a releaser pheromone is a sex attractant
 The most famous sex attractant is probably that of the female silk moth,
Bombyx mori. She emits a minuscule amount, only about 0.01 microgram,
of her powerful sex attractant, bombykol, from a small sac at the tip of her
abdomen
 This pheromone, which is carried by the wind to any males in the vicinity,
binds to the receptor hairs on the male’s antennae. As few as 200 molecules
of bombykol have an immediate effect on the male’s behavior— he turns
and flies upwind in search of the emitting female
 Trail Pheromones: Other examples of releaser pheromones in insects
are trail pheromones, which direct the foraging efforts of others, and alarm
substances, which warn others of danger.

25.  Vertebrates also produce releaser pheromones. For
example, lactating rabbits produce mammary
pheromone, which stimulates their pups to search
for and grasp onto a nipple
 Vertebrates also produce releaser pheromones. For
example, lactating rabbits produce mammary
pheromone, which stimulates their pups to search
for and grasp onto a nipple
 3. Primer pheromones exert their effect more
slowly, by altering the physiology and subsequent
behavior of the recipient.

26.  In insect societies, queens control the reproductive
activities of nest mates largely through primer
pheromones. For example, a queen honeybee
produces several compounds from her mandibular
gland that ensure that she will remain the only
reproductive indi

30. MULTIMODAL COMMUNICATION
 Animals do not always use a single channel when
communicating. In fact, the displays of many
animals contain signals from two or more sensory
modalities. This type of communication is called
multimodal communication, and the signaling in
different channels can occur either simultaneously or
sequentially

32. Characteristic's of different sensory
Channel for Communication in Animals

33. Topic# 2
SIGNALS AND HONESTY
 SIGNALS AND HONESTY
 Four common circumstances under which we expect
to see honest signals:
 (1) when senders and receivers share overlapping
goals,
 (2) when signals indicate something about the
sender that cannot be faked,
 (3) when signals are costly to produce, and
 (4) when dishonest signalers can be identified.

34.  1. If Senders and Receivers Share
Overlapping Goals
 Sometimes both the sender and receiver share the
same goal: the sender benefits by accurately
transmitting information, and the receiver benefits
by accurately interpreting it.
 The coordination of behaviors between animals that
have chosen to mate provides an example. In cases
like these, we expect that natural selection will favor
unambiguous, honest signals.

35.  Example: Begging chicks are quite obvious to
predators as well as parents, so begging too much,
when food is not needed, is a poor strategy
 Parents usually respond to the signal by providing
food to those chicks that beg most vigorously

36.  2. If Signals Cannot Be Faked
 Sometimes signals are honest because they are tightly
linked to a trait of the sender.
 Although the sender might benefit if it could lie, it simply
is not possible to fake the signal.
 Size is usually a good predictor of fighting success, and
many displays allow opponents to judge one another’s
size.
 In some species, combatants can enhance their apparent
size by puffing up their feathers, fluffing out their fur, or
assuming an upright posture, but in other species, size is
not so easily faked. In the threat display of male stalk-
eyed flies

37.  Other signals are honest because they are linked very
strongly to an animal’s health and physiological
wellbeing.
 For example, the bright reds and yellows of feathers,
scales, or fleshy necks or combs of some birds depend on
chemicals called carotenoids. These chemicals cannot be
synthesized by vertebrates but must be obtained in the
diet.
 3. If Signals Are Costly to Produce
 Reliable signals will be favored in a population when
signals are costly to the sender
 Handicap Principle

39.  If Dishonest Signalers Can Be Identified
 A stable social unit also favors honest
communication.
 One reason to expect honesty is that individuals will
both send and receive signals at different times.
 The advantages of sending dishonest signals will be
reversed when the animal is the receiver. Therefore,
the advantages of receiving honest signals might
outweigh the advantages of sending dishonest ones,
and honesty might come to predominate in the
population.

40. WHEN ARE DISHONEST SIGNALS LIKELY?
 If Senders and Receivers Have Different
Goals
 Just as overlapping goals between senders and
receivers favor honesty in signaling, different goals
set the stage for deception
 If Signals Are Costly to Assess or Challenge
 Assessing signals can itself be costly. For example, a
cricket assessing the quality of a singing male must
invest time in listening and may risk attack by
parasites or predators that are attracted to the male’s
song.