We can give simple definition like this. An animal has communicated when it changes the behavior of another animal. But this definition has problems. For example, someone put you in danger, you have change your behavior to safe your...
We can give simple definition like this. An animal has communicated when it changes the behavior of another animal. But this definition has problems. For example, someone put you in danger, you have change your behavior to safe your life. But this isn't a communication.
So we have to look for a clear definition for this. Animal Communication is defined as transmission of a signal from one animal to another so that the sender benefits on average from the response of the recipient.
Modes of Animal Communication
Animals use different modes to communicate each other.
Odor :
One animal produces chemicals typical to the species and another animal of the same species senses this. This mode of communication can be transmitted in the dark. The chemical signals last for hours or days.
Pheromones :
Mostly insects use this type of communication to communicate each other.
Bombykol pheromone which silkworm moths produce is a great example for this. This chemical , produced by the glands in the abdomen of the female silkworm moth, vaporizes in the air. Odor of the chemical triggers a nerve impulse in a receptor cell in the antenna of male. When receiving this signal male moth know there is female moth somewhere ready to mate.
Ants also use pheromones as their communication method. Most of their social behaviors are controlled by pheromones. Eating, finding and exploiting food, recruiting other ants in the nest for battle and warning about enemies are some of them.
In mammals chemical signals are used to mark territories or home ranges. The chemical substances used are often produced by the digestive or urinary systems.
Sound :
This communication method has advantages. Animals use sound in the dark to communicate. Frequency and amplitude modulation is used to convey different information.
Mosquitoes produce a particular frequency of sound by beating their wings at a particular rate. Female mosquitoes avoid males when they perceive the particular frequency of sound produced by the males.
Grasshoppers produce species typical sounds by opening and closing their wings. Male ones use this sound to attract female ones.
Bird song is one of the most complex auditory communications. The sound is produced by blowing air from the lungs so that it passes over the vocal cords in the trachea. Usually male bird is the one who sing songs. Bird songs used to attract mates and to mark territories.
High frequency sounds are used by a variety of animals, especially mammals. Bats use this sounds to find their route and food.
Touch :
This is a short range communication in the form of physical contact. Insects use their antennae to communicate by touch.
Honeybees living place of hives are very dark. So they use touch to pass information about the presence of food to other worker bees in the hive. This is done by dancing.
Surface vibrations :
Water striders are insects with long legs, which lives in fresh water ponds. These insects have the ability to float on the surface of water. They communicate with others by producing ripples at particular frequency in water.
Spiders communicate with each other by making vibrations on the web.
Electric Field :
Some sharks, electric fish and eels have the ability to produce electric fields in the water by special organs. These electric fields produced in the water are used to detect objects and to avoid predators.
Also, communication by electric fields are very useful to animals that live in dark, muddy waters where visual sense is not useful for communication.
Visual communication :
Communicating by visual displays has limitations. A direct line of sight between the two animals is necessary. Secondly communication by this mode can be usually carried out only when there is light.
Fireflies are the best example for using this communication method. Their flashes of light are used in species recognition during mating.
Functions of Animal Communication
Animals communicate with each other for different purposes.
Species recognition :
Species recognition is important to avoid infertile mating between closely related species.
For example there are many species of grasshoppers, which are closely related to each other. In nature a grasshopper will rarely mate with a different species.
Animals use different ways to recognize species. Using pheromones is one of them. Silkworm moth use it. Birds and some insects produce species typical sounds or songs.
Reproduction :
In some species, individuals which are ready to mate and reproduce advertise their condition. For example, female baboons, which are ready to mate and in estrous, develop a red coloration in the anal area.
Agonist and social status :
Agonistic behavior is a system of behavior pattern, which functions in a situation of conflict among the conspecifics. Actual physical combat is costly to animals because of the possibility of death or injury. To avoid this, species have evolved displays to communicate the intention and the mood of an animal.
Alarm :
Animals, which live in groups usually, alert each other when there is danger. Rabbits live in social groups in burrows. They come outside to feed. When predator is detected by a rabbit, it thumps on the ground with its paws and then it runs in to burrow. Just before entering the burrow the tail of the rabbit goes up showing the white color underneath the tail. When the rest of the rabbits hear the thumping noise and see the flash of the tail they ran so quickly into the burrows. This is an example for alarm signal where there is both auditory and visual communication.