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Home › Sea Life › Marine › Vertebrates › Ray Fish Batoids

Information about Marine Rays

[Phylum: Chordata] [Class: Chondrichthyes] [Superorder: Batoidea] [Cartilaginous Fishes]

There are more than 600 different species of rays (called batoids). You can find most of them living in marine and oceanic environments all over the world.

This section contains facts and information about ray fish, including where they live, what they eat, and how they reproduce.

Habitat and Geographical Range of Ray Fish

Almost all ray fishes are bottom-dwellers, living in the benthic zones of tropical and subtropical ecosystems.

By and large, scientists classify marine rays into the following groups:

• Electric rays
• Guitarfish
• Sawfishes
• Skates
• Stingray (whiptailed rays)

Fun Fact: The majority of ray fish are highly adaptable with 'cosmopolitan distribution'. As a result, some species can also survive in temperate, brackish, or freshwater environments.

Unique Characteristics in Sea Rays

Rays are cartilaginous fishes, like their close relatives the shark species (subclass Elasmobranchii). But, there are several distinguishing features that scientists use to differentiate them.

For example:

• Ray fish have a somewhat flattened, discoid shaped body. They have five (5) gill openings and the location for the mouth is nearly always on the underside.
• The enlarged, pectoral fins (that look like wings) create another distinguishing feature. Plus, the winglike fins extend forward at the side of its head and above the gill openings.
• Most marine rays use different methods for swimming and breathing - when compared to sharks. They use their pectoral fins for movement and large spiracles on the upper surface of the head for taking in water (e.g. for respiration).
• The whip-like tail of a ray is long and slender. The tail in many species has several venomous spines that can inflict painful puncture wounds - especially to humans.

Pro Tip: Research suggests that most rays and skate fish (Rajidae) have good vision - especially when the light is dull or faint. They may also be capable of recognising different colours.

Can Rays Bite You?

The spines that exist on the tail of a stingray can pierce human skin. Each spine contains a sheath that will break apart upon contact. As a result, the venom of the spine can release into the puncture wound and any surrounding tissue.

So, stingrays don't bite you per se. But, the sting that occurs from a tailwhip will most often cause pain in the feet, ankles, and lower legs.

What Do Ray Fish Eat?

The role of large, bottom-dwelling predators like sea rays and sawfish is important for the ecology and health of ecosystems that exist on the seabed.

The feeding methods of most ray species, known as 'habitat engineering', tends to stir up the sediment. In turn, this action provides other predators with easy access to buried invertebrates.

Manta rays feed on plankton and small animals; others take:

• A variety of small to medium sized fishes
• Invertebrate crustaceans
• Krill (Euphausiacea)
• Sea shrimps
• Planktonic crabs
• Segmented worms
• Sea snails
• Zooplanktonic organisms

The majority of batoids have heavy, rounded teeth. They use them to crush the shells of some bottom-dwelling species that are difficult to eat, such as clams and oysters.

Ray Fish Reproductive Process

Sexual maturity for a female ray usually occurs around the age of eight. So, they tend to give birth one time every two or three years.

The geographic range, and the time of year, determines when rays start to mate. Even so, the individuals tend to perform their courtship ritual in shallow water. Scientists believe a full moon may be the trigger needed for the mating sequence.

This is the important part:

It can take more than twenty minutes for the male to grasp the female's pectoral fin with his mouth. After securing a tight grip, the male will rotate upside-down so that both ventral sides are close and pressed together.

Following the insertion, the male keeps hold of the female with his teeth as they continue swimming together. Even so, it's common for a few dozen males to follow the mating couple until they finally part company.

How Do Sea Ray Pups Hatch?

As with most ovoviviparous sea creatures, fertilisation of the eggs takes place inside the oviduct. So, an egg case encloses each fertilised egg while the embryo absorbs the yolk as it starts to develop.

The pups remain inside the oviduct after hatching. They will be receiving extra nutrition from a milky secretion produced by the female.

There is no umbilical cord or placenta. Hence, unborn pups will be totally reliant on a process of buccal pumping to get the oxygen that they need. The typical brood size for most rays is usually one (1) but rarely more than two.

Interesting Fact: Marine biologists believe the gestation period for manta rays to be around twelve (12) months. The pup will look like a miniature adult when the female expels it from the oviduct. From this point in time, there will be no further parental care.

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