DIVE DRY WITH DR. BILL #838: THE STAR OF THE NEST
Many years ago, Jean-Michel Cousteau showed me an interesting behavior. As California divers know, our state marine fish, the garibaldi (Hypsypops rubicundus), aggressively defends his nest from all intruders including egg filtching fish or invertebrates and even SCUBA divers. Many a diver has received a bite from one during mating season.
What JMC demonstrated to me was that the garibaldi gets "upset" (a bit anthropomorphic, I know) when a variable star (Linckia columbiae) approaches its nest. The variable star is an egg predator and therefore poses a real threat to the garibaldi's "litter." However, if Poppa is on the ball and not chasing after another lovely female garibaldi to add her eggs to his nest, he can tackle this threat.
Jean-Michel showed me how. By placing a variable star near the nest, he initiated the threat removal behavior. Gary Garibaldi swam over and picked up the variable star by grabbing one of its arms in his mouth. Now variable stars may have anywhere from one to nine arms (rather than the usual five of most starfish... er, sea stars to be PC). I don't know if the garibaldi stops to decide which arm to grasp... probably any arm will do the trick.
Then the garibaldi swims off from the nest and drops the sea star far, far away (well, 10-20 ft). I tried this myself once (or thrice). On the initial removal, the garibaldi didn't take the variable star very far. I retrieved it and placed it near the nest again. This time Gary took it a bit farther away. On the third attempt, the garibaldi swam a good distance away before dropping it!
This year I haven't been diving with a video camera. All four of my video lights need new batteries. One camera housing has an extruded front port o-ring. I have no idea how that happened. Never seen it happen with any of my other video housings. The other housing has a broken control handle mounting ring. I should have sent these in for repair months ago, but I had no idea I'd be diving as much as I am this year.
On a recent dive (my first on Nitrox despite being certified for it several years ago), I was heading back to the stairs from the wreck of the Suejac. I approached some Sargassum ("devil weed") on a rock... and a garibaldi came around from the other side with a variable star in its mouth! Now garibaldi mating season ended some time ago as the water began to cool down (hmmm... when I feel chilly, I want a warm body next to me).
I could think of no reason why the garibaldi would be carrying a sea star in its mouth this time of year. There was no nest to defend, so no eggs to attract the variable star. Although garibaldi will defend a wider territory when not nesting, as a means of ensuring food sources, they are not generally aggressive at this time of year. They will nip at the tube feet of some sea stars, but those of the variable star are too short. So, once again, a new mystery of the deep presents itself to me.
© 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Garibaldi removing variable stars from nest area.
Many years ago, Jean-Michel Cousteau showed me an interesting behavior. As California divers know, our state marine fish, the garibaldi (Hypsypops rubicundus), aggressively defends his nest from all intruders including egg filtching fish or invertebrates and even SCUBA divers. Many a diver has received a bite from one during mating season.
What JMC demonstrated to me was that the garibaldi gets "upset" (a bit anthropomorphic, I know) when a variable star (Linckia columbiae) approaches its nest. The variable star is an egg predator and therefore poses a real threat to the garibaldi's "litter." However, if Poppa is on the ball and not chasing after another lovely female garibaldi to add her eggs to his nest, he can tackle this threat.
Jean-Michel showed me how. By placing a variable star near the nest, he initiated the threat removal behavior. Gary Garibaldi swam over and picked up the variable star by grabbing one of its arms in his mouth. Now variable stars may have anywhere from one to nine arms (rather than the usual five of most starfish... er, sea stars to be PC). I don't know if the garibaldi stops to decide which arm to grasp... probably any arm will do the trick.
Then the garibaldi swims off from the nest and drops the sea star far, far away (well, 10-20 ft). I tried this myself once (or thrice). On the initial removal, the garibaldi didn't take the variable star very far. I retrieved it and placed it near the nest again. This time Gary took it a bit farther away. On the third attempt, the garibaldi swam a good distance away before dropping it!
This year I haven't been diving with a video camera. All four of my video lights need new batteries. One camera housing has an extruded front port o-ring. I have no idea how that happened. Never seen it happen with any of my other video housings. The other housing has a broken control handle mounting ring. I should have sent these in for repair months ago, but I had no idea I'd be diving as much as I am this year.
On a recent dive (my first on Nitrox despite being certified for it several years ago), I was heading back to the stairs from the wreck of the Suejac. I approached some Sargassum ("devil weed") on a rock... and a garibaldi came around from the other side with a variable star in its mouth! Now garibaldi mating season ended some time ago as the water began to cool down (hmmm... when I feel chilly, I want a warm body next to me).
I could think of no reason why the garibaldi would be carrying a sea star in its mouth this time of year. There was no nest to defend, so no eggs to attract the variable star. Although garibaldi will defend a wider territory when not nesting, as a means of ensuring food sources, they are not generally aggressive at this time of year. They will nip at the tube feet of some sea stars, but those of the variable star are too short. So, once again, a new mystery of the deep presents itself to me.
© 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Garibaldi removing variable stars from nest area.
