DIVE DRY WITH DR. BILL #863: MYSTERIES OF THE DEEP I
Some 50 years ago I was a young marine biologist starting out on my first serious research since graduating from college. We were sampling drifting Macrocystis kelp rafts (aka paddies) to see what critters might be on them or following them. The hypothesis was that drifting kelp rafts could provide a convenient (and energy efficient!) way for critters without pelagic larvae to disperse to new habitats such as Catalina.
Being new to the fauna of the Pacific (and before my classmate Al Gore "invented" the Internet) , I often had to seek help from experts to ID what I found. One day I discovered a critter on the blades of a drifting kelp that I had no clue about. I wrote my mentor, Dr. H. Barraclough Fell, at Harvard's Museum of Comparative Zoology using the ancient technology of a letter and included a drawing of the critter. I stated it looked like a Hoover vacuum cleaner with wings... not that I knew anything about vacuum cleaners back then either. Still don't!
Barry wrote back and said it was the nudibranch Melibe leonina. Ever since then it has been one of my favorite shell-less snails. I've written several columns about them. Sadly, I rarely find them in our waters here but they are more common in other areas such as San Diego. However on one night dive back in September of 2013, I found one that has me stumped.
Melibe is a somewhat translucent green which aids in camouflaging it as it roams the kelp blades in search of munchies that it captures with its large oral hood. Therefore it is somewhat difficult to spot unless you have the keen eyes of a well-trained marine biologist. I guess that leaves me out in the cold.
The one I found on that night dive had a number of white spots on it that my high definition camera couldn't resolve. I'd never seen one like that before or since. Now kelp blades start out clean and green but as their growth stabilizes, small invertebrates start to encrust the blades. One of the encrusters is a tiny worm (Spirorbis sp.) with a bright white shell. Older blades are full of these and add other encrusters such as bryozoa and hydroids.
So this mystery from the deep has me bewildered. Is it just a freak genetic mutation? Perhaps an attempt to camouflage even better on the older blades of giant kelp (Macrocystis)? I can't imagine the tube worms attaching to Melibe as it wouldn't provide a very stable substrate. So if any of you divers and biologists out in King Neptune's realm can explain this mystery to me, please feel free to comment!
© 2020 Dr. Bill Bushing. For the entire archived set of over 850 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: "Normal" Melibe with oral hood and kelp blade with white tube worms (Spirorbis) and other encrusters; two views of the "white spotted" Melibe.
Some 50 years ago I was a young marine biologist starting out on my first serious research since graduating from college. We were sampling drifting Macrocystis kelp rafts (aka paddies) to see what critters might be on them or following them. The hypothesis was that drifting kelp rafts could provide a convenient (and energy efficient!) way for critters without pelagic larvae to disperse to new habitats such as Catalina.
Being new to the fauna of the Pacific (and before my classmate Al Gore "invented" the Internet) , I often had to seek help from experts to ID what I found. One day I discovered a critter on the blades of a drifting kelp that I had no clue about. I wrote my mentor, Dr. H. Barraclough Fell, at Harvard's Museum of Comparative Zoology using the ancient technology of a letter and included a drawing of the critter. I stated it looked like a Hoover vacuum cleaner with wings... not that I knew anything about vacuum cleaners back then either. Still don't!
Barry wrote back and said it was the nudibranch Melibe leonina. Ever since then it has been one of my favorite shell-less snails. I've written several columns about them. Sadly, I rarely find them in our waters here but they are more common in other areas such as San Diego. However on one night dive back in September of 2013, I found one that has me stumped.
Melibe is a somewhat translucent green which aids in camouflaging it as it roams the kelp blades in search of munchies that it captures with its large oral hood. Therefore it is somewhat difficult to spot unless you have the keen eyes of a well-trained marine biologist. I guess that leaves me out in the cold.
The one I found on that night dive had a number of white spots on it that my high definition camera couldn't resolve. I'd never seen one like that before or since. Now kelp blades start out clean and green but as their growth stabilizes, small invertebrates start to encrust the blades. One of the encrusters is a tiny worm (Spirorbis sp.) with a bright white shell. Older blades are full of these and add other encrusters such as bryozoa and hydroids.
So this mystery from the deep has me bewildered. Is it just a freak genetic mutation? Perhaps an attempt to camouflage even better on the older blades of giant kelp (Macrocystis)? I can't imagine the tube worms attaching to Melibe as it wouldn't provide a very stable substrate. So if any of you divers and biologists out in King Neptune's realm can explain this mystery to me, please feel free to comment!
© 2020 Dr. Bill Bushing. For the entire archived set of over 850 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: "Normal" Melibe with oral hood and kelp blade with white tube worms (Spirorbis) and other encrusters; two views of the "white spotted" Melibe.
