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Communication - Visual signals

When humans greet each other, eyebrows are often raised. This gives an open, friendly facial expression, unlikely to be aggressive.

Animals also communicate with other individuals among their own species or with other species. One way of doing this is through visual signals.

Though, often they use more than one way of communication at the same time. Such as both visual and acustic signals.

Badges or displays

Communicating by visual signals happens in two ways:

Example of badge. The feathers of the male peacock attract females.

- With structural adaptions (badges), such as color patterns or bright colours. Certain nocturnal animals and those that live in deep-water habitats communicate by light flashes and light patterns. Bright colours may indicate that the animal is poisonous. When aggressive, some animals send a signal by changing colour.

An example of display. When showing its stomach the cat is content and feels safe.

- With behavioural adaptions (displays), such as body posture. For example when a cat arches its back to look bigger and more frightening or when a dog puts its tail betweeen its hind legs to show submission.

These signals often distribute as territorial display in aquatic environments.

Comparison of two different species, how their behavior can be expressed.

Both cats and wolves use tail-, ear- and body posture and facial expressions when communicating visually. A big part of cats’ communication is aimed to avoid other cats and thereby avoid conflicts.

Order in a wolf pack is regularly reinforced by displays of visual signals to show dominance and submission.The posture of the wolf when interacting with fellow pack members easily shows the status of said wolf in the pack. Subordinates try to appear as small as possible and often lick more dominant wolves, the submissive wolf has its ears flat back, close to the head, the tail between its legs and a slumping body posture.

When showing submission, a cat flattens its ears, lowers or even tucks its tail between its hind legs. The cat crouches, as the wolf does, and is likely to lower its head. Submissive cats also avoid eye contact, since it’s seen as a threat.. A crouched position with tail tucked around or under their body and tense muscles, however, indicates anxiousness. To communicate dominance the wolf has its ears straight up or facing forward, tail straight out and slightly upwards. If a cat becomes aggressive, the hind legs stiffen, the rump raises, but the back stays flat, tail hairs lifts, the nose is pushed forward and the ears are pulled back to some degree. This display is used to avoid fights.

Both wolves and cats use visual signals to communicate with other individuals of the same or a different species. Since wolves live in packs they use this sort of communication frequently to set order. Cats usually live by themselves or with very few members involved and therefore does not use these visual signals as often. The level of sociability also differs between cats.

Advantages and disadvantages

Visual signals can only be sent when the receiver is in sight and only lasts as long as the sender signals. Being exposed to the reciever may be disadvantaging for prey species, since the risk of illegitimate receivers is high. However,they can also be beneficial in the same context. The sender can communicate that a predator is nearby without informing the predator that it has been spotted.

How far away from the sender the receiver can be varies between signals. Smaller signals requires shorter distances, and vise versa. The transmission and the fade-out time is fast when using visual signals and many different messages can be sent during a short period of time. Communication through visual signals is however dependent on light, without it the signal is impossible to be received. Nor is it possible when there is a physical barrier between the sender and the receiver.

Some displays are made for the benefit of the sender and disadvantages the receiver, which makes visual communication both benefitting and disadvantaging. “Deceptive signals can lure receivers into responding to the benefit of the sender and the detriment of the receiver. Photuris fireflies are the only predatory species of firefly. By mimicking the female response of the prey species the "femme fatale" Photuris female lures in males, and then preys upon them. Wary males are careful in responding to female displays of their own species for fear of being preyed upon by the Photuris females. In this way, the prey males experience conflicting pressures from natural selection, which demands both individual survival and mating for species survival.” This makes the firefly males have difficulties of reproducing and therefore disadvantages evolution.