THE STINGRAYS
- Friendly Fins
- Nov 18, 2024
- 6 min read
Updated: Mar 7
Why know the stingrays?
“Simply because we notice you from the first moment you put your fin in our environment! We are attentive and discreet observers, nothing and no one can escape our sight, not even you! Very often you confuse us with other inhabitants of the sea, so come and get to know us better!”
How to recognize the sting rays?
Stingrays are more closely related to sharks than they might seem; in fact, they also have a cartilaginous skeleton, but over time they have followed a different evolution:
The stingray has a disc-like shape given by the development and widening of the pectoral fins and snout, becoming one with the rest of the body.
“We have an unmistakable shape! You can’t go wrong!”
The back is mostly flat, we can observe the presence of the eyes and immediately behind them, the spiracles.
The spiracles (openings with respiratory function) are very large. They allow the active entry of water into the animal to be filtered of oxygen and nutrients by the gills. This special adaptation is typical of animals that live in ambush on the bottom.
The mouth is on the ventral side of the body, and is equipped with a very robust set of teeth, with rounded teeth close to each other to create a compact plate.
The dorsal, pelvic and anal fins are often completely regressed, modified or very small. The dorsal fin, when present, appears in a retracted position.
The coloration is very different but the most common colors are brown, from the lightest to the darkest, yellowish, gray and with spots of the most diverse colors.
“Often our color tries to imitate the surrounding environment!”
The dimensions vary greatly: from a few centimetres up to 2-3 metres wide in the largest stingrays.
The tail is long and thin but very robust. It is equipped with one or more clearly visible spines depending on the species.
“This way we can defend ourselves!”
It moves with graceful and very rapid movements, always close to the seabed.
Where does the stingray live and what does it eat?
Stingrays are found in all the tropical seas of the world: from the Pacific to the Indian, but also in some temperate zones such as the Mediterranean Sea and the Atlantic coasts. Most species live on the bottom, both in predominantly coral areas and on sandy bottoms. Some species, however, live among ocean vegetation, called kelp.
“We are very adaptable animals! After all, we have lived on Earth for 400 million years, we have had plenty of time to colonize it!”
Stingrays are nocturnal predators, very skilled and fast; they are called durophagous because they feed on prey such as small fish, crustaceans, molluscs with shells or calcareous skeletons, which they can break thanks to their very powerful teeth.
They are also able to immobilize the prey by forming a sort of umbrella with their disc around it, not allowing it any escape route.
They are not particularly social animals, but with an abundance of food they can create very large groups around the "banquets".
Stingrays reproduction: aplacental viviparity
The stingray is a very long-lived animal, it is thought that it can live up to 70-100 years but there is still much to study.
Male stingrays have two penises called claspers, resulting from the transformation of the pelvic fins. Evolution has brought about this particular development to ensure the survival of the species: if a clasper were to be damaged, they can still have the possibility of mating.
Mating occurs through hormonal recall by the female through behavioral and chemical signals dissolved in water. The favorable period for mating is from spring to summer. Depending on the species, females give birth once every year or every two years.
Gestation lasts three months and the mother produces 2-4 eggs very rich in yolk that guarantee the growth of the fetus until half of its development. From then on, the mother herself will feed them through ingestion, skin transmission or particular structures connected to her intestine; for this reason, rays are viviparous aplacental animals.
Stingrays produce few young and try to ensure their survival by giving birth to large-sized babies that are capable of hunting independently. The female always gives birth in shallow water or in sheltered places in the vegetation to ensure a lower presence of predators. Once the young are born, there is no parental care and the females separate from them immediately.
The electroreception of the stingrays:
Stingrays, like their shark cousins, use their five senses in a superlative way to interact with their surroundings, ensuring a perfect perception of visible and non-visible reality. But not only that… They also have a sixth sense: Electroreception.
Electroreception allows them to perceive the electric fields produced by any living body, within a radius of less than 50 cm. They can do this thanks to special cells (called Ampullae of Lorenzini) filled with electroconductive jelly, located just under the skin and in particular on the snout.
“With this super sense we can be perfect predators even in complete darkness!"
Enemies of the stingrays
The main predator of the stingray is the great hammerhead shark that is very fond of these animals. Thanks to its special snout rich in sensory cells and Ampullae of Lorenzini it is able to detect the presence of the stingray perfectly camouflaged under the sand. Other sharks can also occasionally feed on them.
The weapons of the stingray: sting and camouflage
The stingray, for its part, can defend itself: at the end of the tail there may be one or two clearly visible quills. They are equipped with poison glands that secrete a substance capable of killing cells, also causing muscle contractions. The action of this process is necrotizing and this is combined with the possibility of even serious bacterial infections.
“We sting to defend ourselves and not to attack. In fact, producing the venom is very tiring for us and so we only use it in cases of extreme necessity.”
Furthermore, being an animal that lives and hunts on the bottom, it makes itself “invisible” thanks to camouflage: with color (similar to the environment) and shape (flattened). As if that were not enough, however, the stingray, thanks to its expanded pectoral fins, covers its back with sand disappearing on the bottom, with the exception of its eyes always alert and attentive to the movements around them.
“We are very good at going unnoticed! Often you pass us by and you don't notice anything, yet we are just a few meters away from you, resting!”
Differences between stingray, manta, mobula and sea eagle:
There is often confusion in recognizing these animals, let's clarify a bit:
The stingray lives on the bottom or near it, has a mostly discoid shape with a long and thin tail equipped with one or more spines.
All other animals lead a pelagic life, that is, they live in the water column and soar in a delicate and elegant “underwater flight”, thanks to their pectoral fins which are elongated like a kind of wings.
The manta ray is the most elegant creature in the ocean, it has a kite shape and can reach a wingspan of 7 m. Its back is dark with some lighter shades while the belly is white. Its peculiarity is to have small fins on the sides of the mouth that it uses to channel food.
The mobula, also called sea devil, is similar in shape to the manta ray but smaller and with a brown coloration on the back, its cephalic fins are horizontal and not curved downwards as in manta rays. It moves in large groups.
The eagle ray always has a kite shape but is much smaller than the manta and above all has a very pronounced snout with a mouth equipped with teeth; in fact it does not eat plankton (like the manta) but fish. The back is very dark and in some species decorated with small white polka dots. It also has a long tail that it uses as a whip for defensive purposes.
Finally, another difference is the position of the mouth: in rays it is ventral so if it is on the bottom we will not be able to notice it, while for mantas and sea eagles it is in an apical position and very evident on the snout.
All you have to do is keep your eyes peeled Friendly Fins, a ray is surely already watching you!
Let's learn how to get in touch with her in a Friendly way! Click here!!
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