Costasiella kuroshimae | Hacker News Reader

Costasiella kuroshimae

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153 pointsvinnyglennon56 comments

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.

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.

> please note I am not challenging the scientific truth of evolution

Evolution isn’t a matter of faith, you’re welcome to challenge it and try to poke holes in it.

While true, the predominance of evidence for evolution has reached the point that anybody attempting to argue against it would have to produce absolutely enormous amounts of self-consistent evidence that explains our observations better than modern theories of evolution. It's sort of like the laws of thermodynamics, or relativity, or quantum physics- if you found convincing evidence that any one of those was not accurate, and came up with a better explanation, it would both completely transform science, and open up new avenues for discovery.

And if you want to do that, you should probably get a deep set of experience; otherwise, it's not much different from a flat earther.

theres nothing stopping the entirety of existence as being experienced via wires connected to some brain matter suspended in a jar, one would have to disprove this issue at a meta level to conclusively state any given existential theory as true. therefore all existential theories including atheism are faith based, so to state any one particular theory as true is dogmatic and unscientific

The article notes that the chloroplasts are like a larder that the slug can digest when needs be, so storage could have come well before photosynthesis was actually utilized.

Or maybe it was photosynthesis first. The chloroplasts just did their thing for a while, and slugs that digested them slower (and eventually ones that stored them) got more benefit than ones that didn't.

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.

Closer to the sun (high solar power density) and smaller (lower gravity)... I think we actually have one of those nearby?

Some infinite water supply would be probably helpful there.

Infinite indeed, need to keep it topped off as it all boils away.

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)

I suppose also 'is capable of supporting life' might be an important factor when considering hypothetical life forms.

This is exactly why pokemon devs are looking for biologists! (seriously) https://www.nature.com/articles/d41586-026-00960-8

Real Science video on the slug: https://www.youtube.com/watch?v=IH_uv4h2xYM

Life is amazing.

Stuff like this really makes you wonder what life might look like out in the universe.

Isn't life on this planet also life out in the universe? It depends on your point of view.

[1] Pale blue dot - Carl Sagan https://www.youtube.com/watch?v=wupToqz1e2g

Do you consider things that are inside a house to also be outside a house?

All things are moving in space and time and in relation to other objects so inside or outside are relative points of view.

[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....

I wonder if life elsewhere in the universe is pedantic too.

QED.

[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

If you were so smart, you'd probably find better sources than GQ and Medium to prove your point.

Or Hacker News for that matter. Never trust anything on the internet [1] on face value. Start by asking qui bono? Is this a reputable source, like a scientist[2]?. Be critical and sceptical.

[1] https://en.wikipedia.org/wiki/On_the_Internet,_nobody_knows_...

[2] https://youtu.be/NV0Z6vlIJig?t=216

> sceptical

How can I trust someone who can't use spell check?

I regret to inform you that is the preferred spelling in British English.

I used four spell checkers including Apple, Wikipedia and Google search.

Don't trust anything you read on the internet, including your comment.

Things inside this house are indeed outside that house.

An apartment inside an apartment complex is still inside the same building. Earth is in the Universe. There's a difference between "in the Universe" and "outside of Earth".

A superset also includes everything in all its subsets.

Is the coffee actually in the mug or only on top of it?

In Spanish I don't care.

I'm confused, in es-ar, it can be:

* "El café está en la taza." [preferred]

* "El café está sobre la taza." [I'd never use this.]

* "El café está adentro de la taza."

I'd probably use "en(in?)" for a cup, "sobre(over?)" for a plate an "adentro de (inside?)" for a jar.

Well, can you walk around inside of a coffee cup? If so, you are on it. If not, you are in it.

https://www.eastoftheweb.com/short-stories/UBooks/TheyMade.s... - love this short story and its take on that question.

A classic, and regularly shared here on HN :)

I really like this version of it personally: https://www.youtube.com/watch?v=T6JFTmQCFHg

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.

Some of those things down in the ocean are almost too extraterrestrial... they can stay undiscovered!

They all, so far, share the same basic biochemistry, derived from the Last Universal Common Ancestor (LUCA).

What would be extraordinarily interesting would be if we could find life on Earth with a fundamentally different biochemstry. Very different genetic code, even. This would be sign that Origin of Life is not the Great Filter. And we don't even have to go to another planet to conduct this search for "alien" life.

Sounds like you might be interested in “The Zoologist’s Guide to the Galaxy”.

https://en.wikipedia.org/wiki/The_Zoologist%27s_Guide_to_the...

I remember as a kid wondering if we could give humans chlorolaplasts.

I believe that mitochondria and chloroplast both were originally independent single celled organisms.

So kind of funny that, chloroplast is being "stolen" again by this sea slug.

Yes, it is funny that biological history repeats itself.

https://en.wikipedia.org/wiki/Symbiogenesis

Chloroplasts are but one variety of plastids. Assimilation has occurred multiple times.

https://en.wikipedia.org/wiki/Plastid

Somewhat related https://what-if.xkcd.com/17/

The surface is too small and you only get like 4% of the energy you need (Assuming you like being naked under full sunlight all day long. The article is for cows, but I guess the number is similar for humans.) 4% of 2400 kcal is almost 100 kcal, that is the content of a small diet treat or 2 apples.

These sea slugs can survive because they move very slowly. For a human, I think it's not enough energy to survive even if all the activity is to watch TV inside a hot swimming pool.

Dietary need scales with volume, whereas incident sunlight would scale with surface area.

Assuming a spherical cow and a spherical human, the calories needed would scale with the radius cubed, whereas the calories gained from sunlight would scale with the radius squared. So while I agree this wouldn't be very many calories, even if you sat under the sun all day, I think the 4% figure is probably quite pessimistic.

The square cube law pops up all over the place, my favorite being in fusion reactors, where it is a two edged sword.

Marvelous...

Finally a good reason to assume a spherical cow!

Mmm... Cows weight like 5 persons, 5^(1/3)=1.7, so 4%*1.7=7%, so 170 kcal that is still less than a single cheeseburger.

Real Life Bulbasaur

Probably more like モンメン (Cottonee).

I can definitely see the resemblance to the False Minoshiro's from Shinsekai Yori

We‘re all solar—powered animals.

You know what they meant.

Well it says "indirectly". How much indirect do they mean?

Many bacteria and animals are chemically-powered or electrically-powered. Just one group: https://www.whoi.edu/oceanus/feature/lost-city-pumps-life-es...

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