Bat Ray
Myliobatis californica

 

Physical Description

  • Bat-like pectoral (side) fins are triangular, have rounded tips.
  • Snouts are broad, short, and rounded.
  • Hole called a spiracle behind each eye.
  • They have one to three venomous barbed spines at the base of their long, whip-like tails.
  • Brown, olive, or almost black coloration on top; white on the bottom.
  • Female bat rays are larger than males. Females’ wingspans can reach 6 feet and they can weigh 200 pounds.

Range

  • Found on the Pacific coast from Oregon to Baja California, Mexico and around to the Gulf of California.
  • Also found near the Galapagos Islands.

Habitat

  • Live in muddy and sandy-bottom bays, kelp forests, and near coral reefs.

Reproduction

  • Females mature at 5-7 years old, and males at 2-4 years old.
  • Bat rays are normally solitary, but during breeding season, they come together in large groups.
  • A courting male swims in a synchronized motion below the belly of a female and uses the spines above his eyes to maintain position.
  • After a 9-12 month gestation, 2-5 live pups are born. They are approximately 9-12 inches long.
  • When bat rays are born, the babies have to be careful to not sting the mothers. They are born with soft spines on their tails that are covered in a protective sheath. The spines harden and are ready for defense within a few days.

Diet

  • Bat rays eat clams, shrimp, worms, other crustaceans and mollusks, and small fishes.
  • They flap their pectoral fins to expose buried prey, like clams, and then use their snout to dig out prey.
  • Bat rays have fused teeth that can crush mollusk shells. They crush the entire shell inside their mouth, spit out the shell, and then eat the soft mollusk body.

Predators

  • California sea lions, broadnose sevengill sharks.

Interesting Facts

  • Just like sharks, their close relatives, bat rays are continuously growing new teeth.
  • Bat rays often rest semi-buried in the sand. Do the “stingray shuffle” and shuffle your feet in the sand instead of picking your feet up to reduce the risk of stepping on a ray and getting stung!

Sources: Monterey Bay Aquarium; Aquarium of the Pacific; AnimalDiversity.org 

Photo: Brian McHugh    

Come see a bat ray and its elasmobranch (shark and ray) relatives in person at Birch Aquarium’s Shark Shores or at Living Coast Discovery Center!