Ray Fish

With their flat bodies, rays are unmistakable. They float elegantly through the water. They bury themselves in the seabed to sleep or to ambush their prey.

Characteristics

What do rays look like?

Rays are very primitive fish and, like sharks, belong to the cartilaginous fish family. They don’t have solid bones, just cartilage. This makes their bodies very light and they don’t need a swim bladder like other fish. Their flat body, on which the pectoral fins sit like ahem, is typical. The mouth, nostrils, and the five pairs of gill slits are on the underside of the body.

They also have so-called spray holes on the upper side of their bodies, through which they suck in the water they breathe and direct it to their gills. They sit just behind the eyes. The extra spray holes are important because rays live close to the seabed and often burrow into the bottom. They would breathe in mud and dirt through their gills.

The underside of the body is mostly light. The upper side is adapted to the habitat of the rays, it can be sand-colored, but also almost black. In addition, the upper side is patterned so that rays are perfectly adapted to the underground in which they live. The skin of the ray feels very rough because of the tiny scales on it.

They are called placoid scales and are made up of dentin and enamel, much like teeth. The smallest rays measure just 30 centimeters in diameter, the largest such as devil rays or giant manta rays are up to seven meters tall and weigh up to two tons. Rays have several rows of teeth in their mouths. If a tooth falls out in the front row of teeth, the next one takes over.

Where do rays live?

Rays live in all seas of the world. They are mainly found in temperate and tropical regions. However, some species also migrate to brackish and freshwater. Some South American species such as stingrays even live exclusively in the large rivers of South America. Rays live in a wide variety of sea depths – from shallow water to 3000 meters deep.

What types of rays are there?

There are around 500 species of rays worldwide. They are divided into different subgroups, for example, guitar rays, saw rays, torpedo rays, real rays, or eagle rays.

Behave

How do rays live?

Because their bodies are relatively light, rays are very elegant swimmers. The eagle ray has widened pectoral fins and glides through the water with such elegant movements that it resembles an eagle gliding in the air – hence its name.

All rays are similar in their basic structure, but there are still clear differences between the individual species. The eagle ray, for example, has a beak-like snout. Electric rays are electrically charged and can stun their prey with electric shocks of up to 220 volts. Others, like the American stingray, have a dangerously venomous stinger on their tail. Electric, stingrays, and stingrays can even be dangerous to humans.

Guitar rays deviate the most from the basic structure of rays: They look like a ray in front, but more like a shark in the back. And the marbled ray carries a series of tooth-like structures on its back to protect itself from predators. Rays have a very good sense of smell and touch. And they have an additional sensory organ: the Lorenzini ampoules. They are visible as small holes in the front of the head.

Inside the ampoules is a gelatinous substance that the rays use to sense electrical impulses emanating from the muscular movements of their prey. With the Lorenzini ampoules, the rays can “sense” their prey on the seafloor and find it without the help of their eyes – which are on the upper side of their bodies.

Friends and foes of the ray

Rays are very defensive: some defend themselves with electric shocks, others with a poisonous sting or a row of sharp teeth on their backs. But sometimes rays also flee: Then they press water through their gills and use this recoil principle to shoot through the water at lightning speed.

How do rays reproduce?

Rays lay capsule-shaped eggs with a leathery covering in which the young develop. The shell protects the young but allows water to pass through so the embryo is oxygenated. So that the eggs are not carried away by the current, they have jagged appendages with which the eggs get stuck on stones or plants.

In some species, the young develop inside the eggs inside the mother’s body. The young hatch there or shortly after oviposition. The development time until hatching lasts – depending on the species – four to 14 weeks. The little rays are not cared for by their mother but have to be independent of day one.

Care

What do rays eat?

Rays mainly eat invertebrates such as mussels, crabs, and echinoderms, but also fish. Some, like the giant manta ray, feed on plankton, the tiny creatures they filter out of seawater with their gills.