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I recently played a flash game(Tasty Planet, if you're wondering), where you play play a glob of grey goo that eats planets wholesale. This got me thinking; Why don't the Tyranids do the same? Why do they bother with silly planetary invasions if their motivation is hunger?

Well it would be boring as an army wouldn't it but on a more serious note the Tyranids effectively do devour planets, just with multiple organisms rather than just one big one.

Feasibly a giant goo ball could be killed but matching the various Hive Fleets is much more difficult and hence the species as a whole is much more likely to survive and continue and so far they seem to have done very well so I don't see any reason for the Tyranids to be anything other than the swarm that they are.

I would guess because if they don't crush all occupying forces then the massive feeder tubes that move biomass to the hive ships could be easily destroyed causing a significant loss of resources.

Rock and lava cant be easy to digest

They want biomass not minerals. Thats a reason why they avoid the necrons. Most Tomb worlds are already devoid of life not to mention necrons phase out there damaged units hence even what little they can use out of minerals and such would be way to much of a waste.

They do. All that's left is the most useless rock. There's no point in expending energy carry around 1,000,000 tonnes of granite you're not even going to use anyway.

Well.

Plants digest rock and lava.

All living things are made of inorganic minerals, so there isn't a fundamental problem there.

If Tyranids wanted to avoid eating the rocks, they could drop some spores on a planet which would analyse the bioshere and produce a viral plague that would simply dissolve all life into goo, then suck it up.

It would be an even better way of avoiding all the flamethrower nastiness than eating the whole planet.

But really, why bother eating planets at all. There are gigatons of organic chemicals and water and so on floating around in space.

The IoM isn't interested in it, so the Tyranids could get it for free.

Also an organism of that size would be, well, huge. The bio-engineering of the Hive Mind is good, but is it good enough to produce such a colossal beasty? Also don't the Tyranids get a lot of their genetic make up/design from what they have previously consumed? So in theory that would mean that they would have to have eaten huge, planet consuming creatures in other galaxies (assuming they haven't eaten one in this galaxy, but maybe a void whale would be of the sufficient size/complexity). The complexity of the digestive system of such a planet eating nid, I assume, would be astronomical, sorting out and putting to use all the different minerals and biological material efficiently in one go.

Because it's "not in the script" would be my answer, but I'd justify it by saying that organic material has all that inorganic material can offer plus the added bonus of genetic base material which is useful to them. They are organic material and consuming such is simply natural.

On the other hand, one might say well, why not simply stay on a planet till everything is gone? A hive fleet might well take a VERY long time to reduce a planet to nothing. Taking every useful thing available. After all, organic material is just a thin layer of "pond scum" on a rock, isn't it?

Then again, maybe there IS something "motivating" the hive fleets other than pure hunger and other such simple Darwinian concepts.

Because Eldrad told them not to.

You're underestimating the sheer mass of a planet, as well as the amount of energy that would be expended to break it down. It doesn't even make sci fi science sense.

Stages of Planetary Consumption:

Generally, contact with the Tyranids occurs when a Hive Fleet invades a star system for the purpose of harvesting its inhabited worlds' biomass. A Hive Fleet contains an enormous number of Tyranids, and they are brought to bear against resistance in the most efficient manner possible.

Below is a general outline of a typical Tyranid planetary assault (in particular, this data is collected from the Tyranid invasion of Dalki-Prime):

■Day 01: Mycetic spores are dropped, mostly containing Lictors and Genestealers. As soon as they hit the ground, the reproduction of Tyranid creatures likely begins immediately.

■Day 09: By now, the Tyranid infestation will have expanded to around 250 km around the drop point, and will likely present a significant threat to planetary defense force troopers and the resident Imperial Guard.

■Day 13: Tyranids have expanded to 700 km from the drop point; some may begin infesting local water sources.

■Day 37: Tyranids completely control the area within 2,000 km radius of the drop point and basolithic infestation has begun to reach a 5,000 km radius from the drop point of the first mycetic spores.

■Day 48: Tyranid population growth becomes exponential, with population doubling approximately every 3 days.

■Day 50: The main Hive Fleet arrives, with the number of Tyranid craft in the swarm generally numbering around 1.5 billion. All psychic contact with the planet through the Warp is cut off by the Warp shadow of the Hive Mind. Any attempts to escape are quickly stopped by the Hive Fleet. Any remaining surface life is eliminated by Gaunts.

■Day 51: Primary consumption of planetary biomass begins (any sentient resistance has generally been eliminated by now). Brood ships land, releasing Ripper swarms, which consume all organic material (even the other Tyranids) and deposit it at the reclamation pools. Capillary towers (and the Brood ships) send the material into orbit for use by the Hive Fleet.

■Day 80: Ripper swarms board the Brood ships and return to the Hive Fleet. The hive ships descend into the upper atmosphere and begin collecting it. Reduction in atmospheric pressure causes oceans to boil away, which are also collected so that their free water can beused by the fleet. The loss of ocean mass causes plate tectonic shifts, dramatically increasing volcanic activity across the victimized world. Upon completion, the Hive Fleet reenters the Warp, in search of fresh prey.

■Day 100: The Imperial Navy arrives in response to the planet's original Astropathic distress call, only to find a destroyed, lifeless, uninhabitable planet.

Kilkrazy wrote:Well.

Plants digest rock and lava.

All living things are made of inorganic minerals, so there isn't a fundamental problem there.

If Tyranids wanted to avoid eating the rocks, they could drop some spores on a planet which would analyse the bioshere and produce a viral plague that would simply dissolve all life into goo, then suck it up.

It would be an even better way of avoiding all the flamethrower nastiness than eating the whole planet.

But really, why bother eating planets at all. There are gigatons of organic chemicals and water and so on floating around in space.

The IoM isn't interested in it, so the Tyranids could get it for free.

I think people underestimate how much they take. They take the air, the dirt even the diamonds. The a point of diminishing returns to hualing around a bunch of carbon.

There is a lot of carbon in organic chemicals.

If the Tyranids scooped things up from space, they could drop or spit out the carbon they didn't want.

Kilkrazy wrote:There is a lot of carbon in organic chemicals.

If the Tyranids scooped things up from space, they could drop or spit out the carbon they didn't want.

The main thing 'nids want more than anything by far is DNA. Yes, I know there's space whales flying around but the best place to go for that is still planets.

Of course the Tyranids may well have some kind of planet eating beasty, it just hasn't arrived yet and for all we know the Tyranid organisms so far revealed are the most insignificant of the Tyranid organisms. However, in the face of such a massive creature, the lesser Tyranid creatures range ahead so that they can get a feed, devouring all the biomass before the big boy turns up and eats literally everything.

Because even after all that fluff and discussion about it, it's still just a tabletop wargame.

Tyranids do kind of need to be an army to can actually play on said tabletop.

KamikazeCanuck wrote:

Kilkrazy wrote:There is a lot of carbon in organic chemicals.

If the Tyranids scooped things up from space, they could drop or spit out the carbon they didn't want.

The main thing 'nids want more than anything by far is DNA. Yes, I know there's space whales flying around but the best place to go for that is still planets.

DNA is just a chain of chemicals. Every body makes its own DNA all the time. Tyranids are masters at manipulating DNA. They can make their own DNA much quicker and better than stealing it form other people.

The purpose for going to planets is to fight people to get better at fighting people on planets in order to go to planets to fight people to get DNA and resources, but these are more easily available in space without fighting.

From what I've read the Tyrannids absorb DNA and then replicate it. Using a form of hyper-eugenics instead of creating it from scratch. Which is why a certain space marine chapter is guarding a race of creatures to prevent them (the tyrannids)from harvesting that races specific "potential".

Kind of supports the Darwinian theory of development compounded by the seeming complexity of a vast organism. Although there may be some "guiding force" or supreme intelligence which assists the species as well.

Scientists have created a synthetic genome in the lab in our own time, so how hard it would be for a species such as the Tyrannids is open for discussion. Though I think it's possible that both ideas may be true, unless there is some specific drive which causes Tyrannids to create DNA, which I don't think is supported in the text (or is it?!), that the Darwinian absorb and modify is the easiest explanation for why they don't devour the whole planet.

Then again... http://en.wikipedia.org/wiki/Geophagy

Creating synthetic DNA, and coding new DNA, are two entirely different things. The Synthetic DNA that got created has only a minor variation from the original organism (a watermark of sorts).

Cobourn wrote:Stages of Planetary Consumption:

Generally, contact with the Tyranids occurs when a Hive Fleet invades a star system for the purpose of harvesting its inhabited worlds' biomass. A Hive Fleet contains an enormous number of Tyranids, and they are brought to bear against resistance in the most efficient manner possible.

Below is a general outline of a typical Tyranid planetary assault (in particular, this data is collected from the Tyranid invasion of Dalki-Prime):

■Day 01: Mycetic spores are dropped, mostly containing Lictors and Genestealers. As soon as they hit the ground, the reproduction of Tyranid creatures likely begins immediately.

■Day 09: By now, the Tyranid infestation will have expanded to around 250 km around the drop point, and will likely present a significant threat to planetary defense force troopers and the resident Imperial Guard.

■Day 13: Tyranids have expanded to 700 km from the drop point; some may begin infesting local water sources.

■Day 37: Tyranids completely control the area within 2,000 km radius of the drop point and basolithic infestation has begun to reach a 5,000 km radius from the drop point of the first mycetic spores.

■Day 48: Tyranid population growth becomes exponential, with population doubling approximately every 3 days.

■Day 50: The main Hive Fleet arrives, with the number of Tyranid craft in the swarm generally numbering around 1.5 billion. All psychic contact with the planet through the Warp is cut off by the Warp shadow of the Hive Mind. Any attempts to escape are quickly stopped by the Hive Fleet. Any remaining surface life is eliminated by Gaunts.

■Day 51: Primary consumption of planetary biomass begins (any sentient resistance has generally been eliminated by now). Brood ships land, releasing Ripper swarms, which consume all organic material (even the other Tyranids) and deposit it at the reclamation pools. Capillary towers (and the Brood ships) send the material into orbit for use by the Hive Fleet.

■Day 80: Ripper swarms board the Brood ships and return to the Hive Fleet. The hive ships descend into the upper atmosphere and begin collecting it. Reduction in atmospheric pressure causes oceans to boil away, which are also collected so that their free water can beused by the fleet. The loss of ocean mass causes plate tectonic shifts, dramatically increasing volcanic activity across the victimized world. Upon completion, the Hive Fleet reenters the Warp, in search of fresh prey.

■Day 100: The Imperial Navy arrives in response to the planet's original Astropathic distress call, only to find a destroyed, lifeless, uninhabitable planet.

Some of this is no longer canon (for example the Tyranids no longer use the warp to travel).

I think that the Tyranids don't eat the whole planet because the gases that Mycetic Spores release (they aren't all used to transport beasties) as well as those released by the tyranid bio spires aren't capable of breaking down billions upon billions of tons of rock into the bio mass gruel that is consumed by the Tyranids.

And while DNA is important to the Tyranids as it allows them to adapt keep in mind that they are all living creatures in one way or another and so much of the harvested biomass goes to providing the energy for all those life forms either by creating them or allowing them to live.

Minerals (magma and lava are just minerals in liquid form) hold very little nutrients and so the energy spent breaking them down woulden't be worth the energy consumed from them. That's why very few if any creatures on Earth eat rocks for purpose of protein, now yes some minerals are important and are ingested through the food we eat but that food isn't rock. It's the same thing with the Tyranids, they're just a mass of living creatures seeking to further their existance on a planetary scale.

Yeah, I was trying to make that point, but stopped short. Synthetic DNA being as far as we've come with 21st century tech. How far can the Tyrannids go in the 41st milenium?!

Creating DNA seems too technologically specific. It sort of implies building constructs without the benefit of specific experience. Instead of fast eugenics which is how I see the Tyrannids. I hope I'm not missing out on a bunch of fluff which says otherwise.

In that case ignore everything.

Because I imagine that the rock isn't to tasty...

Because we are playing Plothammer and not Sensiblehammer

@Killrazy
Tyranid are unique in that they are fully cognizant and fully in control of their dna. Norn Queens move genones around like lego pieces. They cannot it would appear evolve new genomes on their own or are subject to the slight mutations normal life has every generation. In the end, they are literally gene stealers.

Exactly.

So they have no need to attack planets in order to get genes that are good for attacking planets in order to get genes that are good for attacking planets.

Kilkrazy wrote:Exactly.

So they have no need to attack planets in order to get genes that are good for attacking planets in order to get genes that are good for attacking planets.

That's equivilent to the crazy guy on the radio who says we should stop all research because we've already invented everything we need.

No it's not.

Tyranids can make their own genes.

They have no reason at all to pinch the genes of a 21,798th human planet.

Planets are too big. The world's deepest drill is 7 miles deep, two feet wide and has taken many years to reach said depth. 7 miles is like a grain of sand gouged into the skin of a watermelon. To process an entire planet is near impossible.

Also, if they have no planet, food can't regrow on the planet.