Invertebrates with starships.

[frigidmagi]

While I know and understand that gaint upright ants ain't happening, I begin to wonder, is a backbone required equipment for dragging your specis into sapientcy and interstellar travel?

Can the not so noble starfish inherent the earth and the stars or is this a verebrates only party out in the cold dark?

[Mayabird]

To get on land (it's hard to smelt and use metals underwater) and move around enough to build things, creatures would need some sort of support structure to hold up the body against gravity. I'm not a biomechanics person so I don't have any numbers to support this, but I don't think a backbone is the only way a support structure could be set up. Heck, on a planet with less gravity and/or a much higher oxygen content, an exoskeleton might even work. Earth back in the day (Carboniferous period) had dragonflies with meter wingspans and five foot long millipedes. Even assuming that intelligence and the ability to develop technology require a certain size, it could work.

That's all I can think of now. There are probably many, many other ways it could work, and the only reason I can't think of them is a lack of imagination.

[Josh]

Basically as Maya said, you have to be able to manipulate tools with sufficient strength to carry out resource extraction and fabrication.

Now, taking into account that this is science fiction, there are alternate answers in terms of extraction...

Take the notion of a species that 'eats' rock, such as a land-octopus type creature that exudes acid and extracts nutrients from liquified dirt and rocks. You've got a primitive form of mineral extraction possible there from modifying their feeding behaviors a tad. You've got the hurdle to cross of why they'd develop sentience and expand their intellectual behaviors, and then build them up from there.

[LadyTevar]

Aren't there actual videos of octopi unscrewing bottle lids, crawling inside, and then screwing the lid back on for protection? That proves that squid and octopi both have the manipulation skills to take the first step. As for needing water, a planet with a lush rainforest or heavy moisture content to the air may allow them to crawl out of an ocean environment.

[Josh]

I move that we make a project of this and design a starfaring octopi species.

We're postulating at least amphibians, so we'll need our resident amphibian expert.

[Shark Bait]

how about cephalopods with internal semi viscous fluid filled sacks in certain locations that gives them a little structure existing on a slightly lower grav world with good oxygen levels? like it has been said several species of octopus are very intelligent and they do have a centralized brain, the big invert vert question is not a back "BONE" its the use of a notocord basically the nervous tissue used to send complex signals up and down the body. In theory this could be accomplished with a series of ganglion and a nervous net.

Edit: Animals waterproofing themselves without shells is not hard so a cephalopod non permeable skin. With a repertory system perhaps as evolved as a birds with active air exchange would certainly be able to live on land. Though such complex lungs would be tricky, maybe a system similar to some species of fish with highly efficient gills and internal water storage as well as highly vascularized "sinuses". meaning basically cavities with lots of veins and such close to the surface that acts like a pre-lung of sorts. (beta fish have this and if they cant gulp air at the surface they actually drown)

[Stofsk]

Traveller depicts an alien race called the Hivers, who resemble giant starfish. (well, man-sized - giant relative to most starfish)

They're known and feared as manipulators.

[Cynical Cat]

There's a series by Charles Sheffield (Convergence, I think it's called) which has a species of bad ass land cephalopod.

[Josh]

Yeah, I like Bait's basic structure. The big question was getting them up and functional on land.

[LadyTevar]

Well... there is the idea of the Swampus, an amphibous octopoid, as well as the Squibbon, a primate-like squid that was hinted to have the beginnings of sentience. Both creatures are from The Future Is Wild, a speculative fiction produced by Animal Planet TV.

[Comrade Tortoise]

No, a spine is not strictly required. What is needed will really depend on environmental constraints. With lower gravity physical support becomes much easier. The nervous system as Bait has said can be done with gangion and a nerve net. So intelligence is not strictly a problem.

One issue however would be muscle attachments. Without an internal skeleton, the ability to attach muscles strong enough for resource extraction and fabrication will be difficult. But that is not to say an answer does not exist.