I just got to see a different species of kleptoplastic sea slugs in the wild last month, on a kayak tour of the mangroves around Key West. Our guide scooped some lettuce sea slugs up in a plastic container (and then returned them safely). They were bigger, about 3 inches long, with a wavy/frilly green border. It made my biologist heart very happy!
That was likely a sea slug from the Nudibranchia order (they resemble lettuce sea slugs sometimes) which are a bit different from Sacoglassa order slugs like the one in TFA in that they carry symbiotic algae colonies, rather than digesting them and keeping the chloroplasts like Sacoglassa.
Some things on Earth (especially in the ocean) you'd think were extraterrestrial... What a gift to still be able to find such amazing animals out there.
This is one of those times evolution doesn't make sense to me. It's clear how a giraffe's neck evolves, the ones that could reach higher leaves in trees had an advantage. In examples like this, how does this evolve when there is no gradual change? An animal had to exist that had an offspring that somehow both absorbed the chloroplasts of the food it ate in a way that it could use (not just simple digestion), then have a place to store them, then have a mechanism to move the chloroplasts to the storage space, then have the mechanisms in their body to use the energy the stored chloroplasts create. How does that happen gradually when each step is totally useless without the others?
(please note I am not challenging the scientific truth of evolution, I simply do not understand how something like this happens)
They look kind of translucent to me, maybe the first of this kind of slug just had a digestive problem that didn't break down the chloroplasts, and the minimal energy through their bodies made those individuals more successful because they didn't need to eat as often as those who digested theirs. Yada yada other errors among the indegestible-chloroplast population showed further advantages when it's closer to the skin, they outcompeted their peers, etc.
Makes you imagine a world with high solar power density and maybe lower gravity or something where larger land animals might be realistically supplemented by solar energy as well.
Now I think of a scifi setting, where rich people use massive ressources to feed their artificial gardens on Merkur with water from comets, so the genetically engineered solar powered green butterflies in their garden can keep flying.
(But there might be more expensive adjustments needed, like rotation speed)
So kind of funny that, chloroplast is being "stolen" again by this sea slug.
https://en.wikipedia.org/wiki/The_Zoologist%27s_Guide_to_the...
I really like this version of it personally: https://www.youtube.com/watch?v=T6JFTmQCFHg
[1] Pale blue dot - Carl Sagan https://www.youtube.com/watch?v=wupToqz1e2g
[1] https://en.wikipedia.org/wiki/Special_relativity
[2] Point of view is worth 80 IQ points - Alan Kay. He didn't specify the sign....
[1] Why people hate smart individuals: Studies reveal it's linked to your own intelligence level https://www.gq.com.au/health/wellness/studies-say-who-you-ha...
[2] On the importance of being pedantic https://medium.com/@lfloridi/on-the-importance-of-being-peda...
[3] Pedantic definition https://dictionary.cambridge.org/dictionary/english/pedantic
[4] Pedantic opinion https://www.vocabulary.com/dictionary/pedantic
(please note I am not challenging the scientific truth of evolution, I simply do not understand how something like this happens)
(But there might be more expensive adjustments needed, like rotation speed)