DIVE DRY WITH DR. BILL #747: BAT RAY MATING
Last week I wrote about what dirty rotten scoundrels bat rays (Myliobatis californica) are and how I despise them. Their munching behavior not only reduces visibility immensely, but they chow down on some critters I happen to like. Today I'm going to focus on the other "m" word that bat rays do... mating. Mothers, now is the time to stop reading this column to your youngsters.
Bat rays are known to enter shallow, warmer waters in the spring. The ladies are the first to do so, followed by the males... you know, "where the girls are." Many species prefer warmer conditions for mating, most likely since higher temperatures accelerate the development of the young. I can't verify that this applies to the bat ray, but it probably is true. Would I lie to you?
Now the girls reportedly live longer than the boys, perhaps to the ancient age of nearly a quarter century. Even though their growth rate is slower, females are generally significantly larger than the males due to their longer lifespan. While the boys become men by age 2-3 years, it may take as long as nine years for the girls to become reproductively mature.
Dr. Milton Love states that bat rays mate shortly after the females give birth. If they had legs, they'd probably be labelled as "barefoot and pregnant" most of their adult lives. Some Homo sapiens believe in that philosophy as well, but not yours truly! I just like them brilliant and beautiful (the mind, the mind)! While inside the female's uterus, the embryos derive nutrition produced by the mother. They remain inside for about 9-12 months with as many as a dozen youngsters born mostly during summer and fall.
I've had several opportunities to film bat rays "in the act." No, they weren't part of the cast in some underwater play. I'm talking about doing "it." I've got to be a bit cryptic since you may still be reading this to your child.
One time I was diving off Long Point here on Catalina when I came upon a pair of bat rays. Being the highly trained marine biologist I am, I could immediately see one was male and one was female. No, they weren't wearing pink and blue... but the male possesses two structures near the tail known as claspers. They are used to insert his gametes into the female.
The female lay on the rocky bottom in a cluster of giant kelp. The male kept approaching her from different angles. He seemed to want to position himself beneath her, and kept "nosing" under her body towards the tail end. Now I'm not a vulgar voyeur, so I swam away to give them a little privacy.
The most unusual mating I've filmed happened out at Middle or Isthmus Reef outside of Two Harbors (aka the Isthmus). I was at the south end of the reef, hanging on to a rocky outcropping to film something on the wall. I sensed something swimming behind me and turned, still hanging on with one hand, to see a pair of bat rays flying united (an airline I hope to never use again after they misplaced my luggage).
I was able to capture video footage of the pair swimming in mid-water. The larger female was in a normal attitude, swimming with her dorsal side up. The smaller male was "hanging" on upside down beneath her with its claspers connecting the two. It was quite a sight! Not exactly sure which of the Kama Sutra positions they were using, but it seemed to work for them.
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Male bat ray's claspers and bat rays flying united; Male bat ray attempting to mate with female on the ocean floor.
Last week I wrote about what dirty rotten scoundrels bat rays (Myliobatis californica) are and how I despise them. Their munching behavior not only reduces visibility immensely, but they chow down on some critters I happen to like. Today I'm going to focus on the other "m" word that bat rays do... mating. Mothers, now is the time to stop reading this column to your youngsters.
Bat rays are known to enter shallow, warmer waters in the spring. The ladies are the first to do so, followed by the males... you know, "where the girls are." Many species prefer warmer conditions for mating, most likely since higher temperatures accelerate the development of the young. I can't verify that this applies to the bat ray, but it probably is true. Would I lie to you?
Now the girls reportedly live longer than the boys, perhaps to the ancient age of nearly a quarter century. Even though their growth rate is slower, females are generally significantly larger than the males due to their longer lifespan. While the boys become men by age 2-3 years, it may take as long as nine years for the girls to become reproductively mature.
Dr. Milton Love states that bat rays mate shortly after the females give birth. If they had legs, they'd probably be labelled as "barefoot and pregnant" most of their adult lives. Some Homo sapiens believe in that philosophy as well, but not yours truly! I just like them brilliant and beautiful (the mind, the mind)! While inside the female's uterus, the embryos derive nutrition produced by the mother. They remain inside for about 9-12 months with as many as a dozen youngsters born mostly during summer and fall.
I've had several opportunities to film bat rays "in the act." No, they weren't part of the cast in some underwater play. I'm talking about doing "it." I've got to be a bit cryptic since you may still be reading this to your child.
One time I was diving off Long Point here on Catalina when I came upon a pair of bat rays. Being the highly trained marine biologist I am, I could immediately see one was male and one was female. No, they weren't wearing pink and blue... but the male possesses two structures near the tail known as claspers. They are used to insert his gametes into the female.
The female lay on the rocky bottom in a cluster of giant kelp. The male kept approaching her from different angles. He seemed to want to position himself beneath her, and kept "nosing" under her body towards the tail end. Now I'm not a vulgar voyeur, so I swam away to give them a little privacy.
The most unusual mating I've filmed happened out at Middle or Isthmus Reef outside of Two Harbors (aka the Isthmus). I was at the south end of the reef, hanging on to a rocky outcropping to film something on the wall. I sensed something swimming behind me and turned, still hanging on with one hand, to see a pair of bat rays flying united (an airline I hope to never use again after they misplaced my luggage).
I was able to capture video footage of the pair swimming in mid-water. The larger female was in a normal attitude, swimming with her dorsal side up. The smaller male was "hanging" on upside down beneath her with its claspers connecting the two. It was quite a sight! Not exactly sure which of the Kama Sutra positions they were using, but it seemed to work for them.
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Male bat ray's claspers and bat rays flying united; Male bat ray attempting to mate with female on the ocean floor.
