Urobatis

Urobatis is a genus of rays in the family Urotrygonidae, commonly known as round rays. They are found in the eastern Pacific Ocean, from southern California to Peru. Round rays are characterized by their distinctive circular or oval body shape, flattened appearance, and relatively small size. Their pectoral fins are broad and fused to the head, creating a disc-like shape. They have a short, pointed snout, a small mouth, and five gill slits. The dorsal surface is covered in rough skin with a variety of colors and patterns depending on the species.

Reef stingray – Urobatis concentricus

Spotted round ray – Urobatis maculatus

Yellow stingray – Urobatis jamaicensis

Haller’s round ray – Urobatis halleri

Urobatis pardalis

Tumbes round stingray – Urobatis tumbesensis

Common Names

Round rays are known by various common names, including:

  • Round stingray
  • California round ray
  • Pacific round ray
  • Shortnose round ray
  • Southern round ray

Characteristics

The genus Urobatis encompasses several species, each with unique characteristics. They typically range in size from 20 to 60 centimeters (8 to 24 inches) in length. Some distinguishing features include:

  • Body Shape: Circular or oval, flattened body
  • Pectoral Fins: Broad, fused to the head, forming a disc-like shape
  • Snout: Short and pointed
  • Mouth: Small, located on the ventral side
  • Gill Slits: Five pairs of gill slits
  • Tail: Whip-like tail with a single dorsal fin and a venomous spine located near the base of the tail
  • Coloration: Varies depending on the species, ranging from brown to olive green with spots, stripes, or blotches.

Environment

Round rays are primarily found in coastal waters, including:

  • Estuaries
  • Bays
  • Muddy bottoms
  • Sandy bottoms
  • Rocky reefs

They prefer shallow waters with temperatures ranging from 10 to 25 degrees Celsius (50 to 77 degrees Fahrenheit). Round rays are typically found at depths of 10 to 100 meters (33 to 328 feet).

Diet

Round rays are carnivorous and feed primarily on:

  • Small invertebrates, such as crabs, shrimp, and worms
  • Small fish

They use their sensory organs, such as their ampullae of Lorenzini, to detect prey buried in the sand or mud. They then use their mouths to suck up their food.

Reproduction

Round rays are ovoviviparous, meaning that the eggs develop inside the female's body. The embryos receive nourishment from the yolk sac and are born live.

References