Science questions not worth a thread I: I'm a moron!

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Other than chordates, are there any phyla with species that currently live in the ocean but whose ancestors were terrestrial? I would think there might be some arthropod examples of this, but are there?

EDIT: I should specify "fully aquatic", as in they don't spend any part of their life cycle on land.

Whales? Just throwing that out there, I should've googled "phyla" and "chordates" before I answered though...
 
Sea snakes? (although wiki tells me one species can move on land)
 
Oh I dunno! I'm a mathematician and computer programmer!

What about prawns? Did they live on land ever? (I have absolutely no idea :lol:)
 
I've heard some poisonous beasties have venom that will kill a person instantly. Faster even than the venom can travel to vital organs. How does that work?
 
I've heard some poisonous beasties have venom that will kill a person instantly. Faster even than the venom can travel to vital organs. How does that work?

Stings from a Box jellyfish could send people into shock and drown them before the venom reaches the heart and causes a cardiac arrest.
 
Stings from a Box jellyfish could send people into shock and drown them before the venom reaches the heart and causes a cardiac arrest.

But my question is, how does it happen that quickly? If the poison does not actually reach the vital organs before the effect takes place, how does that happen?
 
But my question is, how does it happen that quickly? If the poison does not actually reach the vital organs before the effect takes place, how does that happen?

A sting from a box jellyfish sends a lot of small darts(each with venom) into the body, and the darts can cause enough to pain to send a person into shock. If not that, then the burning sensation from the venom being released will. If you're lucky enough to survive that, then the venom will quickly travel to the heart and send you into a cardiac arrest.
 
I'm starting to think that panspermia is looking better and better in contrast to the idea that life on Earth is native to Earth.

If we believe that life spawned in early Earth, than the conditions had to be just right, right? So the Earth since than has been unsuitable for life to spawn from non-life, otherwise we would see examples of non-life turning into life at more than one point. UNLESS, it is that unlikely.

Please help me figure out where I'm going wrong or fill in the gaps of info that I'm missing.
(maybe my assumption that life only happened once is wrong to begin with?)
 
I'm starting to think that panspermia is looking better and better in contrast to the idea that life on Earth is native to Earth.

If we believe that life spawned in early Earth, than the conditions had to be just right, right? So the Earth since than has been unsuitable for life to spawn from non-life, otherwise we would see examples of non-life turning into life at more than one point.

Not necessarily; once life got properly started it presumably spread to every place that was suitable for early life quite rapidly, this changed conditions such that they were no longer suitable for abiogenesis (for instance, by the simple fact that all those complex organic doodads that could have some chance of combining into primitive life would rapidly get eaten by primitive life that was already there).

There may very well have been any number of false starts that fizzled out, or even possibly competing "first primitive life" types of thingies that may have existed during overlapping times, of which one of the types were more effective than the others and ate them all. More or less impossible for us to know.
 
I didn't mean to imply some sort of religious belief on my part is some kind of "magical" cause for life or the universe. I definitely see no reason to believe in a deity or creator, but I am not opposed to the concept of panspermia. It's much easier for me to come to grips with.

And I've more or less "calmed down" since my post (I was a little tipsy and the post came while watching some science channel tv show). A single occurrence of life being formed seems a lot less crazy to me now :p It's like asking why didn't humans evolve independently in geographically/temporally isolated instances.

tl;dr: false alarm
 
I didn't mean to imply some sort of religious belief on my part is some kind of "magical" cause for life or the universe. I definitely see no reason to believe in a deity or creator, but I am not opposed to the concept of panspermia. It's much easier for me to come to grips with.

I know, it was an analogy. The fact remains that as far as I can see, saying that panspermia is easier to come to grips with or accept or whatever than abiogensis is similar to the First Cause argument, in that you are not changing the fundamental issue, just changing where/when it happens.
 
The issue I was having, was not "can life come from non-life" which would indeed be a problem that panspermia simply does not address, as you pointed out, neither does a creator, evolution or ID.

My issue was: "why hasn't life come from non-life more than once?" Which now seems to be like me asking why didn't humans evolve multiple times independently.

I was watching the show "The Wormhole" with Morgan Freeman, and the idea of "life as we don't know it," was brought up to maybe explain that life did evolve from non-life more than once, and we can't recognize these other "kinds" of life because they are so different from our own (non-carbon based or something).
 
My issue was: "why hasn't life come from non-life more than once?" Which now seems to be like me asking why didn't humans evolve multiple times independently.

Because if it arose again, it would be too primitive to compete with the life that was already there.
 
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