How often must carnivorous grassland eat?

Question

Don't go into the bonegrass. Seriously, unless you want to be dead. You go in there, brush the grass with your clothes, start to feel sleepy...

Before too long your limbs will go numb, then you're on the floor in a heap. Then you're dead but you don't know it yet. The grass you crush as you fall will grow up through your bones, your flesh will feed its neighbours and your blood will water its children.

Oh, and did I mention you being awake right up until you're dead?

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Bonegrass (so called because of its bone white colour and propensity for killing things) is a rapidly growing (4–5cm/day) form of wheat. It grows to its full height in just under a month, emits specialised paralytic pollen and then uses the nutrients of its prey to fuel its growth and spread (as most prey succumbs near the edges of the bonegrass field). Its seeds are heavy and lay dormant on the ground until something falls on them, at which point they have a growth spurt and start to work their way up through the prey.

The prey (for their part) are enticed to the bonegrass fields because it's a remarkably good source of nutrition if you don't fall down and die before getting away. The seeds (to fuel their rapid growth spurt) pack a lot of calories.

The question is how often a patch of bonegrass would need to capture and kill (non-sentient) prey in order to maintain a balance between 'enticing food source' and 'deadly patch of death, do not approach'. This is going to affect how the densities of the paralytic pollen change over time, varying between attracting prey with free food and then killing everything in order to spread a bit further.

Answer 1

I think for this we'll need to look at real life.

Carnivorous plants tend to be adapted to grow in places with high light where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs and rock outcroppings.

So the soil where the bonegrass grows could be very nitrogen poor.

The important thing to remember is that carnivorous plants aren't eating their prey for the sake of energy.

They're eating their prey for the trace minerals and nitrates they contain. The plant doesn't need to eat in the same way that a human does. They're getting food or calories from light. Once a patch of ground is fertilized by dead creatures it could remain fertile for quite some time until the trace nutrients escape or are washed away by rain.

How often they have to eat is entirely a matter of how efficiently the bonegrass can recycle nutrients after it's absorbed them.

It would also make sense for the bonegrass to take advantage of some of the same tactics which natural carnivorous plants use.

It could produce suger-water to attract insects.

Keep in mind, the plants are likely to have lots of energy to spare but be very short of nutrients. So they could produce high-energy, low nutrient seeds to attract birds. The birds are either caught and killed or perhaps some species are immune and their droppings provide the bonegrass with nutrients.

Like this happy little fellow:

If you decide to make some creatures immune they could live among the grasses like clownfish among venomous stinging anemones.

This would allow the deeper sections of the grass to survive and would also provide more reasons for people and predators to enter. If big, tasty migrating birds stop in the middle of the bonegrass then their droppings help keep it alive and provide more reasons for people to enter the region.

Minor side note, paralytic pollen sounds terrifying. Whenever the winds are blowing from the direction of the bonegrass fields you'd have people collapsing, unable to move. Better hope you're not high up or doing something dangerous at the time.

It opens up a silly origin story for the bonegrass poison: weaker versions of the pollen cause creatures muscles/sphincters to relax, making them more likely to defecate. A strong version evolved which leaves creatures unable to move at all, thus providing their whole bodies to fertilize the plant.

Answer 2

Have you thought about not just making it one creature, but two? It could be two separate beings living in extremely close proximity, like how a lichen is a moss and a fungus.

The plant part, the Bonegrass, would be the part that’s obviously visible and above ground. This part is basically a plant, save for the alluring pollen that attracts and paralyses its prey. It makes glucose the good ol’ fashioned way, with water, sunlight, and CO2. The only problem is that this kind of plant also grows in pretty nutrient poor soil, because reasons.

The solution to this problem is the Bonegrass’s little microbiological buddies. Millions of microscopic, carnivorous life forms live in and under the grass, and whenever the grass lures in a new form of prey, they wait until it’s paralysed, and then get to town. They eat anything that’s worth eating, digest the flesh, and leave the nutrients the plant needs behind in their waste.

Metabolically speaking, this is a cost-effective way for two species to form a symbiotic relationship and gain what they need. If the grass had to wait for it to rot, it would probably be mostly picked clean by decomposition bacteria or scavengers, and if it digested it itself, that would require an absurd amount of energy for a plant. But with a two-man system, the grass lures in the prey with food and paralyses it, and the microscopes life forms do all the work digesting it and deposit the nutrients left behind directly into the soil.

This is actually pretty similar to something that does happen, called biological nitrogen fixation, where bacteria that live on the roots of pretty much all plants convert atmospheric nitrogen into ammonium, a nutrient which plants need.

With this kind of system, and assuming the microscopic lifeforms only take what they need, I’d assume that one corpse could sustain a few square meters of Bonegrass for a few weeks, at least. Depending on what you make the lifeform, it could possibly go out and find food, then bring it back in times of prey-drought.

Of course, this is really all about metabolism. The Bonegrass could adapt in any one of a thousand different ways to stretch out the nutrients, possibly widening the window to months. it could go dormant, or slow down its metabolic rate, or possibly something different and completely alien that we don't even have. Evolution be crazy. Sorry I can't be more specific, but the whole metabolic process is so complex that you’d have to work out an entire ecosystem around this one plant. In short through, yes, I do think It's feasible, and the frequency of prey would probably be less relevant then what the plant does with it, and how efficient it is at using what's given.

Answer 3

Bonegrass is a fungus, which feeds once every seven years.

Bonegrass is a white fungus which grows in wheat fields. Most of the time, the bonegrass fields are normal wheat fields, indistinguishable from other wheat fields except for their exceptionally high yields and relatively low numbers of animal inhabitants. Of course, this entices lots of animals, large and small, to move into the area. Populations boom, fueled by the seemingly unnatural abundance of the wheat.

And then the bonegrass blooms. Overnight, huge mycelial mats below the wheat fields become active, with white fungal growths growing up the stalks of the wheat plants, using their stalks for support. Then, simultaneously across hundreds of square miles, the bonegrass releases its paralytic spores. Within 12 hours, the wheat fields become pale, white places of death. The fungus then begins to grow over the paralyzed creatures, flooding their body with neurotoxins that keep them immobilized until they die from dehydration over the next few days.

The dead animals quickly break down, broken apart by the fungus. As suddenly as the bonegrass grew, it will then die back, shrinking back beneath the earth, where it will slumber as the land above it slowly repopulates, drawn by the seeming gaia above the soil, and unaware of the horrors slumbering beneath...

Answer 4

The bonegrass would likely still need to be able to get nutrients from the ground through their roots (at least enough to survive), because any stationary predator can have a long wait, in between meals. Large anaconda's can wait 6 months or more between decent meals.

I would expect that the bone grass would accept any animal protein, and I would also expect at least a few animals that are immune to the pollen as well. The ones immune if smaller, might not only live among the grass, but die there as well, giving back to the bonegrass. They might even entice predators into the grass.

But most animals that live in proximity to the Bonegrass would learn to generally avoid it, or at least longer exposure, unless certain stresses trigger the killing effect. Meaning that a herd of deer walk through/nearby the grass everyday on their route, and one day say to much drought (a week without rain) and the bonegrass is feeling a little peckish, so it is set off the next time deer walk through and the first half make it through without any trouble but in the middle they die and the ones in the back turn around when some start collapsing.

Though I could see communities cultivating these fields if the fruits are good. Likely they would use this instead of burying their dead, give them to the bone grass! And any animal remains not considered worth eating, Periodically small children will wonder in and it will be a loss to the community.

Despotic rulers would cultivate it as a form of capital punishment.

Answer 5

One of the problems your bonegrass will have to deal with is... uh... bones.

Drawing in an animal, killing it and absorbing the nutrients is the easy bit. The problem is how to deal with what's left over; the bones.

If you've ever left an object out on the lawn for a length of time, you'll know what happens; leave it long enough and the grass underneath dies off and you end up with a dead patch in your lawn.

If every animal that gets caught by the bonegrass leaves its bones behind, then you're going to end up with loads of dead patches in the grass. Especially as no other animal that might want to eat or retrieve the bones can come into the grass to get them without suffering the same fate.

Another problem you're going to have to work out is how far into the grass field an animal is likely to get before it succumbs. This will limit the size that your bonegrass field can reach, as the grass in the center will stop getting any nutrients.

Both of these issues could be dealt with by having some kind of creature living among the grass with immunity to it. Probably a scavenger that has evolved to feed off the animals drawn into the grass. This would give it a symbiotic relationship with the grass, in that it would eat the bones and move the carcasses, and thus solve problems for the grass.

Answer 6

First I just want to say I think this is a really cool idea. Wish I had thought of it.

I'm not that knowledgeable on the subject so someone might need to correct me on this. But I lived in a desert environment and there was no grass. Just dirt. Nothing, nothing, nothing. Then one day it rained. The next morning there was a sparse, but very green grass everywhere. It looked so incredibly fertile.

The point is, that grass didn't seem to have any nutrients but stayed dormant until it did. Maybe your grass just grows more when it gets more animals.

Also, the squirrels in Iowa (when I lived there briefly) fattened up for winter, but the squirrels in Florida just look the same all year. Maybe your grass could be like that too. They just depend on the food source and other environmental conditions.

Finally, I think I might have missed something. Is this a plant or a grass-like animal? You mentioned wheat but then at one point you said it could react like "other" animals.

Answer 7

To keep bonegrass a viable source of food, the bonegrass shouldn't kill too often. Around once every two weeks. It means that people aren't dying that often, which means that I can still get food, but enough nutrition so that the bonegrass doesn't die. This means that the 'danger level' for bonegrass will be something like 'good food , but approach with caution!'!

Answer 8

Check Sheri S Tepper's book "The Companions" for a few ideas there.

IIRC there's something called "redmoss" which has euphoric/soporific qualities. Basically you end up drugged out of your mind, you die happily (because you don't feel the need to eat or drink), and the redmoss uses your body as fertiliser. The group responsible for interplanetary exploration are fully aware of this, and anyone who develops something incurable during their missions is given the option to "redeploy" here for a peaceful exit.