The sense organs play a very important role in the life and behavior of fish. Fish, like other vertebrates, have a complete set of five senses. But they have a significant difference - the side line. In fish, this sense organ is called the sixth. Terrestrial animals in the process of evolution have lost this sixth sense, but in waterfowl it remains and pretty much makes their life easier, helps them survive and feed.
Anatomy of fish. Sensory organs
One of the main sensory organs in fish is the sense of smell and taste. With their help, they are able to capture even minor changes in the environment. Pike fish, for example, with the help of the mouth not only eats, but also, sensing a touch of the ground, instantly reacts, changing direction. Sensitive cells located in the mouth transmit nerve impulses, signaling danger, the appearance of obstacles or food.
The fish have a rather finely developed temperature sensation. Such a high sensitivity to fluctuations in temperature and pressure is unusual for terrestrial animals.
The olfactory organs of fish are located on the lateral parts of the head and resemble small cones. With their help, they can capture changes in the chemical composition of water. Especially sharply developed sense of smell in those animals that conduct night hunting. For example, pike fish can sniff prey that swims a few meters from it.
Side line. Location
Many scientists believe that the sideline in fish is the most important sensory organ that helps animals live more comfortably. The lateral line is a kind of a single center that combines all the sensitive cells in the body located in the head or body.
The organ is located throughout the body, starting at the head and ending at the tail. Anatomy of fish, their variety and subspecies determine the location of the lateral line and its color. In one species, it may look like a bright white line, in others - a dark, almost black stripe.
In a larger number of fish, the lateral line is presented in a single specimen. But there are some species that can boast of five or more. The lateral line in the fish can be very visible visually, and can be hidden in the scales and immediately invisible to the human eye. In some fish it has an arched shape, in others - in the form of small jerky stripes on the head.
There are fish that are devoid of the sixth sense organ. These include mullet, dallia, and some fish of the carp-like family.
The sideline consists of ...
As we have already said, the lateral line in the fish is a kind of brain and nerve center that allows you to control what is happening around. What does this center consist of?
The lateral line is an accumulation of a number of receptors that are located at a certain interval. Receptors can be located in the channels on the head or indentations that are located on the sides of the body. Most receptors are hidden under the skin of the fish. Only a few come to the surface and are hidden in scales. Remind open pores on the skin.
Inside, the sideline channel is filled with fluid. Nerve receptors (their sensitive hairs), catching changes, give a signal to this same fluid. Any movement, change in pressure or temperature of the water can cause the receptors and, therefore, the water in the channel to move. The stronger the changes in the fish habitat, the more the hair-receptors will deviate, the faster the information gets into the central nervous system.
The value of the lateral line in fish
The sixth sense, or side line, allows the fish to feel the approach of other animals living in the water much earlier than their visual or olfactory organs have informed them. The lateral line is able to capture the smallest changes in pressure in the water. Scientists say that the distance at which she is able to determine the imminent danger is six times the size (length) of the fish itself.
The value of the lateral line in fish with low vision is especially high. There are animals that are able to respond exclusively to shadow or light, while completely not noticing movement in the water. The lateral line in this case allows you to compensate for the underdevelopment or lack of visual or olfactory skills.
The life of the fish often depends on the sideline. If it is damaged, then external influences will be perceived by the animal not so brightly. It will cease to respond to outside danger, will not be able to fully hunt, obtain food, and hide from enemies. And soon perish.
Sideline and nibble
Surely all experienced fishermen know the importance of the sideline in fish. With its help, the fish is able to catch the slightest noise and fluctuations in water. As the experts say, a shot, an explosion, a normal conversation on elevated tones, a blow to the water, the side line will immediately “smell”. And the fish, therefore, will react, get scared and hide. It is for this reason that fishermen try to never make noise in a pond, not to speak too loudly, not to throw something into the water.
Movement, small noise and vibrations should not be created by a fisherman, but by bait in the water. Experienced anglers say that the bait should not stand in a pond, it must certainly move, making fluid oscillations. Only in this case, the fish with its lateral line will smell food and will move in the direction of the hook.