The electric ray is fairly easy to distinguish from other underwater animals. Outwardly, these fish look like a disc, reaching 3 feet (50 cm to 1 meter) in diameter with a slight elongation in the form of a movable tail, decorated with a fin. On the sides of their rounded body are paired organs that generate electricity. In nature, there are 69 species of these fish, divided into four families.
The origin of the rays is still a controversial issue. In the most common variant, stingrays evolved from sharks, some of which have changed their usual mobile lifestyle for a moderate bottom habitat. As a result of these changes, the shape of the body of animals and the functioning of organ systems have changed.
In the scientific literature, their ancient ancestor is mentioned, which existed about 58 million years ago. The fossils found testify to the great external similarity of the ancestor and modern individuals. The ancient representative had a similar body shape and a long, sharp tail, with which the animal hit its prey or protected itself from enemies.
The appearance and features of the electric ray
The body is rounded flat in shape, a small tail with a caudal fin and 1-2 upper fins. The pectoral fins have grown together, giving the fish a more rounded appearance and forming the so-called wings. The protruding eyes and breathing holes are clearly visible on the head. In most cases, vision is relatively well developed, but in some species it is practically absent, and the eyes are immersed under the skin, for example, in representatives of the genus of deep-sea electric rays. These types of vision are replaced by electroreception – the ability to perceive the slightest electrical impulses emanating from living organisms and other senses.
The oral and branchial slits are located on the underside of the body. During breathing, water enters the gills through the holes in the upper body and exits through the holes below. This way of breathing has become a distinctive feature of all stingrays and is directly related to the lower lifestyle. If, breathing, they swallowed water with their mouths, like sharks, then sand and other soil elements flowed with the water to the gills, injuring the organs. Therefore, the intake is carried out from the upper side of the body, but the water pushed out from the gill slits helps to wash away the sand in search of prey. Due to this arrangement of the eyes and mouth, the rays cannot physically see what they are eating.
The upper part of the body has a very varied coloration, which depends on the color background of the habitat. It helps the fish to camouflage and hide from predators. The range of colors ranges from dark, almost black, like a black electric ray, to a light, beige color, like some species. The patterns on the upper torso are very varied – in the form of stripes, patterns or spots. The lower part of the body in the predominant number of species is light.
Where do electric rays live?
These are mainly bottom dwellers. They live in bays, on reefs, near sandy beaches. Some species dive to 3,000 feet (1,000 meters). The electric beam is mainly found in seas and oceans with tropical and subtropical climates. But some species live even in Arctic waters, where the water temperature is 1.5-2 ° C.
What do electric rays eat?
The diet of electric rays includes plankton, annelids, cephalopods and bivalves, crustaceans, fish and various carrion. To catch mobile prey, stingrays use discharges of electricity generated by paired organs at the base of their pectoral fins. An electric ray hangs over the victim and, as if hugging its wings, at this moment releases a discharge of electric current, stunning the victim.
The electric ray got its name due to its ability to generate a charge in its body from 8 to 220 volts (depending on the type of fish). First of all, this ability is necessary to compensate for poor vision due to electroreception – “probing” with the help of electrical impulses of the surrounding world.
The electric ray releases a stream of electrical particles and shakes everything around. Parts of the body that are isolated from electricity do not allow themselves to be stunned.
All stingrays are characterized by a solitary lifestyle. As mentioned above, they prefer to spend the daytime calmly, lying on the bottom or burying themselves in the sand. In moments of rest, they scan the surrounding area using electroreception, identifying potential prey or enemy. In the same way, they are able to communicate with each other, transmitting and capturing electrical signals like bats.
Social structure and reproduction of electric rays
For some electric rays, viviparity is characteristic, when all stages of development occur in the mother’s body and full-fledged individuals are born. With this method, small stingrays develop and are born twisted into a tube, the only way they can fit in the uterus, especially when there are several of them. For electric rays, embryonic uterine nutrition of the embryos is characteristic due to special outgrowths, similar to villi, through which nutrients are supplied from the mother’s body to the embryos.
Other species use ovoviviparity, when embryos enclosed in hard shells are located in the uterus. These eggs contain the nutrients necessary for the development of the embryo. Maturation takes place in the eggs that the female stingray bears, up to the moment the offspring hatch.
Another option is egg production, when the female lays peculiar eggs containing a large supply of nutrients, fixing them on the substrate elements with the help of special cords.
Young, newly born or hatched fish are already capable of electric current. Due to the fact that the offspring is born well adapted to survival, the number of embryos in different species does not exceed, on average, 10. Sexual dimorphism is characteristic of stingrays.
Natural enemies of electric rays
All stingrays, including electric ones, are hunted by larger predatory fish. In most cases, these are sharks of different species. Precisely because of the presence of a large number of natural enemies, camouflage coloration, bottom lifestyle, night activity and protection by electric current allow them to maintain their numbers.
Population and status of the species
The danger for these animals is represented by commercial mass catches of fish, where they accidentally fall. Gillnets for other fish species and squid traps are also used to trap stingrays. When caught in a huge mass of caught fish, most stingrays die.
An electric ray is very dangerous to humans
Electric rays do not intentionally attack people. They pose a danger to humans when in contact with them. Electric shock is not fatal, but dangerous in that it can lead to immobilization or loss of consciousness. But, being in the water, having lost consciousness, a person can drown.Such a meeting can take place on any shore where stingrays live. It is difficult to notice them during the day, so you should follow the rules for safe swimming in such places.
How does an electric ray shock?
If you look at the electrical ray from below, you will notice on its abdomen convex “tubercles”, which are modified muscles, the so-called “accumulators”. It is in these organs that an electric charge is generated. The functions of oppositely charged “poles” are performed by the belly and back of a flat fish.
Stingrays have complete control over the current generated in their body. A special part of the brain is responsible for this, so spontaneous discharge never occurs. In addition, fish that generate electricity also know how to control the force of blows – from the micro-pulses necessary for orientation in space to powerful blows.
Interesting Electric ray Facts:
- These fish are quite suitable for food. Some of the meat and liver are edible. But due to the danger of electric shock, the fishermen choose not to mess with them.
- There are no bones in the body of the stingray. Their skeleton is entirely made up of cartilage tissue.
- Also, these fish are called “sea butterflies” – when the stingray swims, one gets the impression that a huge butterfly is flying under the water. An especially strong optical illusion if the skin of a flat fish is decorated with bright patterns.
- The mechanism developed by stingrays for hunting and protection is used by humans during the creation of electrical medical devices such as a pacemaker.