Assuming that of the 108 instances of shark rubs, none got eaten, because the article didn't say otherwise. The title says "despite risk of being eaten" so this data point would be interesting
Tuna use sharks as back scratchers despite risk of being eaten
21–30 of 54 posts
Re: Tuna use sharks as back scratchers despite risk of being eaten
#22If this seems strange, remember that tuna have no arms. How else would they scratch themselves?
Re: Tuna use sharks as back scratchers despite risk of being eaten
#23I wonder how many years of evolution it took for tunas to target the back end of a shark instead of the front.
And how many more years it will take before tunas can grow fingernails and scratch their own parasites off?
Re: Tuna use sharks as back scratchers despite risk of being eaten
#24Between this and the Hemingway post the other day, HN seems to have a weird tuna fixation, stay tuned-a
Re: Tuna use sharks as back scratchers despite risk of being eaten
#25I wonder how many years of evolution it took for tunas to target the back end of a shark instead of the front. And how many more years it will take before tunas can grow fingernails and scratch their own parasites off?
Although the article is riffing on "nosh rubs itself on a food blender", there were not really very many samples of that behaviour seen. 106 rubbings in total, some against a shark and some not - unclear, let's say 50. They mention over 100,000 individuals seen.
I'd venture that evolution isn't involved at all and it is simply opportunism that was observed. It's such a rare event that we can't science this one much.
Before you grow fingernails, you need to grow fingers. Before you grow fingers, you need something to wave them around on otherwise they don't do much - that'll be arms (or legs). Fish have been there, seen it, done it (multiple times) and reverted too (multiple times).
Re: Tuna use sharks as back scratchers despite risk of being eaten
#26There's all sorts of weird relationships between sharks and other fish. Like the fish that live off by performing dentistry for sharks inside their mouths. https://www.youtube.com/watch?v=V5EszU8yuA8
One of the fish in the piccy in the article looks like a remora - not a dentist, more a general hygienist.
Re: Tuna use sharks as back scratchers despite risk of being eaten
#27If this seems strange, remember that tuna have no arms. How else would they scratch themselves?
Seabed, rocks etc.
Re: Tuna use sharks as back scratchers despite risk of being eaten
#28Re: Tuna use sharks as back scratchers despite risk of being eaten
#29I wonder how many years of evolution it took for tunas to target the back end of a shark instead of the front. And how many more years it will take before tunas can grow fingernails and scratch their own parasites off?
I wonder if its a learned behavior versus something instinctual.
Re: Tuna use sharks as back scratchers despite risk of being eaten
#30It must have been a really troublesome itch to take that risk!