how do birds flock and fish shoal?

[Amorphos]

how do birds flock and fish shoal?

just a short question i have sometimes pondered. i am sure many of you have seen the wonderful displays on 'springwatch' [tv show] where thousands of birds make patterns in the sky - whats it all about eh!

btw i dont think it is simply eye contact and following. it may have something to do with elecro magnetism - same as they use as a guide to find their way across the world, but i really dont know much about all of this.

[Chaigidel]

I think it has something to do with the magnetic stuff in all our brains, allowing us to instinctually sense directions, and return to places of similar "feeling"-- i think its called magnatite or some thing but its in almost every things brain.

other than that I think that animals including humans find patterns relaxing, so they form them almost all the time even without thinking.

[Amorphos]

interesting chai, i saw a nature program which showed that birds followed a magnetic stream of sorts, to find their way across continents. i notice that when i get up off the sofa my dog gets up to at exactly the same time [to within tenths of a second], perhaps as you say we all have some kind of connection. it has been said that there is no em activity outside of the body though except in terms of static? secondly, this doesn’t explain how my dog knows when i am coming home!

as for patterns, thats a whole different language

[Chaigidel]

there is probably some sort of energetic "superstructure" to all tangible reality, wherein we are connected somehow, I mean the em field of earth is constantly flowing through the fields we produce, and the same with all things, plants recognize one another as well, they even give less competition if the plants around them are part of the "family" and put more power into root production if they are part of another plant "family" ( a group of plants descended from the same plant not a genetic family)--- it is probable in my eyes that the unseen connections between things probably are connected in some way with the over all electromagnetic spectra which is wrapped around each piece of matter.

[Amorphos]

yes i think so too, i also wonder how plants and animals know what poison is? perhaps there is more connectivity and on a universal scale than one presumes.

[Quacky]

As far as i remember shoaling and large groups of birds are not formed by the animals themselves thinking lets make a giant swarming mass of creatures but just the result of what they are doing. Each animal tries to stay a certain a distance from all the surrounding animals. If everyone does this you end up with a large mass that seems to stick together and gives quite bizarre movement at times.

As far sensing magnetic fields its not very well understood but I think its only really birds brains that use it and it is just like a compass using the earths magnetic field.

Im guessing by poisons you mean how they evolved not just how they know about them. Clearly to know about them such as a plant containing a poison is just that the animal tried to eat it and it got sick or died and learnt from this. Then this knowledge is passed on. The plant can evolve this because if 1 plant can make a poison then the animals don't eat it so much so it will out compete all the other plants that can't make the poison. Like a snake would have to rely on contriction and the bite alone if it didnt have a poison but the poison lets it tackle far larger prey.

[Bootsiuv]

As far sensing magnetic fields its not very well understood but I think its only really birds brains that use it and it is just like a compass using the earths magnetic field.

I know that sharks hunt other fish by sensing electrical currents in the water which is caused by other fish moving through the water. This is how they are able to hunt in complete darkness....perhaps fish use this same ability to control their movement in schools....although I'm not certain if this is the same process.

[Amorphos]

quacky

Each animal tries to stay a certain a distance from all the surrounding animals

i think it is far to immediate for that to be the whole reason.

Clearly to know about them such as a plant containing a poison is just that the animal tried to eat it and it got sick or died and learnt from this

good answer! how would it know which chemical caused the animal to be sick, and how would they know that the animal itself was sick? they could deduce [by chemical transplant or something] that they are not being eaten as much as usual, but that is all. what i am thinking is that there is a pattern to how things evolve - perhaps.

Like a snake would have to rely on contriction and the bite alone if it didnt have a poison but the poison lets it tackle far larger prey.

true, yet how does the snake know that a given chemical causes harm. i presume that a certain kind of snake would natural and coincidentally have toxins in its saliva, thus it could produce more saliva upon realising its effect. however you would then have poisonous snakes which produce huge volumes of saliva rather than a specific chemical toxin.

here’s another one for ya; how do colour-blind or indeed blind, deep see creatures know what luminescent colours [that they produce] are?

[Quacky]

I think you arent quite understanding how evolution is working here, the organisms aren't making a change and then deciding is this good and working nicely. The plant example makes a poison randomly that just happens to have an effect on the animal. It has no idea that this works or not but the result of it is that the particular plant is not eaten and so can grow happily. The plants able to produce the poison since theyre not eaten out compete those that cant. What exactly the poison does to the animal doesnt matter to the plant just the effect of not being eaten.

As for producing large amounts of saliva with low toxin concentration again the expression of genes can vary so some would produce higher concentrations of the certain toxin. These would waste less energy producing lots of soliva that they dont require (producing saliva requires a lot of ion pumps to control its concentration and secrete things into it). For a lot of snakes the availabilty of water might make this occur faster where a snake producing a lot of water would struggle. Not as clear cut as developing the toxin to start with but it is still possible to generate this.

Im guessing you mean the sort of fish that have a luminescent lure for hunting rather than squid type colours for communication and things which obviously are not blind. The fish itself doesnt produce the light rather bacteria that produce light when they reach a certain number (quorum sensing) and the fish provides resources for them. Since this acts as a lure attracting some of its prey, a lot of the fish are not blind but have huge eyes to detect very low light levels. Having the lure it finds more prey near it than one that doesnt.

Other fish use this sort of thing on their underside to camoflage them against the surface on the sea so they dont produce a shadow. The ones able to do this wont be eaten so much by predators that can see the colours. They themselves dont need to be able to see this.

[Ramashan]

This is actually an article in the most recent National Geographic magazine. Their explanation is, to put it quite simply, that each concentrating on their surrounding to such a degree that any action causes an instant change in the group.
ie: One fish moves away from danger, all the surrounding fish emmediately follow. They use fish and wilderbeast also as examples. Check out the article, they explain it much better then I can.

There's a great series of photos of a Perigren Falcon attacking a flock of birds.

[Amorphos]

quacky

The plants able to produce the poison since theyre not eaten out compete those that can’t

so they should be the only plants left if they can survive best. so poisons are purely accidental? yet it is said [on any given documentary etc] that plants produce them as a defence! so with plants and snakes there are many cases where we are left with the question; why! why do they produce these toxins... hmm perhaps over long periods of time the plant produces strong acids [or similar compounds] as it doesn’t get eaten as much it keeps making them stronger - as a chemical reaction to environment. toxins are perhaps similar.

thanks.

Im guessing you mean the sort of fish that have a luminescent lure for hunting rather than squid type colours for communication and things which obviously are not blind

partly, but arent most fishes colourblind, - same with chameleons, octopus etc?

Other fish use this sort of thing on their underside to camoflage them against the surface on the sea so they dont produce a shadow.

interesting! how on earth that converts is a mystery to me - i mean they note that the surface is bright, then over time as a result of this the body produces an effect similar to it?

ramashan

i would think there is an amount if dilution and variance for bird movements. it is like when someone brakes on the motorway, half a mile back the cars are all stopped. ...same with fish.

it is all too immidiate for indinvidual reactions.

[chris_uk_83]

Quetz, you seem to be making the classic mistake that species can think themselves into evolution. They can't and they don't, it's completely random.

Let's take the luminous fish as an example. Fish in the deep water swam around happily until one day a predator decided to go deeper than them. It looked up and saw its prey looking like shadows against the light coming from above. "Nice", it thinks, "an easy way to spot my prey!" and proceeds to scoff a bunch of fish that it can see easily. These fish die and never reproduce. One day, one fish is born that has a slight blue glow on its underbelly by accident. This fish can't be seen as easily by its predator, though it doesn't know why, so it survives and breeds, making more fish with glowing underbellies.

Over time there will be fish born with less glow and more glow. Those with less glow will be seen more easily and will be eaten, preventing them from breeding. Those with more glow will be harder to see and will surive, passing their genes along. Eventually you reach now, where one species contains exclusively glowing fish.

Plants work the same way. Those 'born' with randomly poisonous leaves accidentally survive, and pass on poisonous leaves to their descendants. Over time, the ones with more poison survive better than those with less poison until we end up with a species of poisonous plant. In tandem with this, those animals that like the smell of this poisonous plant will die quite quickly and won't breed. Those that dislike the smell won't eat it and will survive. Therefore the "defence mechanism" that documentary programs talk about has evolved over millions of years. They don't mean that one day a plant thought "ooh, I'll make myself a defence mechanism". That doesn't happen.


As for the other topic: birds are believed to navigate by sensing the Earth's magnetic field. There are also some fish that can sense electric fields. Every living thing has an electric field because it runs on electricity (albeit a small amount). This allows these sensitive fish to detect their prey.

[Amorphos]

chris uk
nice reply!

These fish die and never reproduce. One day, one fish is born that has a slight blue glow on its underbelly by accident.

yeah right! this presumes every variant is taken in arriving at that - but you wont find evidence of many variants. or perhaps it all comes down to chance, what is the chance that fishes would develop in this way without a process of ‘knowing going on? when we add all the cases together chance seams somewhat out of the question.
there are species of insect that change specifically to the tree they inhabit [i saw this on a documentary by david attenborough lol], which means that evolutionary change can be quite quick - just look at how quickly humans have changed over the last 20-40 thousand years. i think the thoughts we have have an effect if repeated over long periods of time.

Those ‘born’ with randomly poisonous leaves accidentally survive

doesn’t that sound a bit suspicious to you?

Over time, the ones with more poison survive better than those with less poison until we end up with a species of poisonous plant

strange how the animals that eat them didn’t develop anti toxins!?

They don’t mean that one day a plant thought “ooh, I’ll make myself a defence mechanism”. That doesn’t happen.

sure - that sounds suspicious too. however rather than being completely random i think there are patterns to how things develop, rather than have a million subspecies we actually get reasonably specific species. thus poisonous plants and animals are part of the pattern of transformation. my reasoning is that nature always finds ways to minimalise failure, the best way to do this would be to have better forms/types already encoded in the dna.

[Quacky]

The tree thing youre talking about I think a classic example of moths in industrial revolution. Its not so much evolution though because the two types of moth existed before so had already evolved. Before the industrial revolution most the trees they landed on had quite a light coloured bark so it was better for them to be white themselves but there were still a few black ones about just the population was mainly white. Then we started burning tonnes of coal and polluting everything and the trees mostly had a covering a soot and become darker so the black coloured moths survived better so the population became biased towards the black moths as they were camouflaged. This reversed again when we stopped burning so much coal.

Some animals have developed anti-toxins. Its sort of like an evolutionary arms race the plant starts to make some kind of toxin but still it suffers a small amount of attack by animals. Some of which may randomly produce something that neutralizes the particular the poison. This animal feels no effect of the poison and so eats the plant like any other. Possibly more than others since its likely to be quite abundant with other animals not eating it. With this large supply of food it can bread happily and creat a population of similarly resistant animals. The plant then has to develop some other method of defence against this population it may lose its ability to produce the initial posion too since theres a cost to produce it and it confers no advantage to the plant a plant that doesnt make it can grow just as well but without using energy to produce the poison.

There are a few examples of what you say of other forms of things in the DNA already. Trypanosomes (a type of single celled parasite) have hundreds of copies of membrane proteins so your immune system develops resistance to 1 and then some will switch to using a different one to continue the infection. Antibodies work by alternative splicing where they use different bits of DNA stuck together to give the possibility of a huge a range of antibodies so you can develop immunity to almost anything.
The key thing is these give an advantage to having multiple copies of the DNA, its quite energy expensive to replicate extra DNA that you would need to have multiple copies of every gene not to mention the control of their expression, some genes are controlled simply by how many copies of them there are and so if you make multiple copies of every gene you have far more to control by other again energy using methods. If it already had the other better form it has already "evolved" and wont use the old form so it might as well be lost from the genome to save the expense of replicating it all the time.

[chris_uk_83]

yeah right! this presumes every variant is taken in arriving at that - but you wont find evidence of many variants.

No, because all the other variants get eaten and die, because they're not successful.

doesn’t that sound a bit suspicious to you?

Not really; it seems logical that those plants better suited to survival will survive.

Random mutations aren't that uncommon, just think of different people you know. They will be different sizes, have slightly different skin tones, hair colours etc. Some may have large mutations, such as an extra arm (I have a friend who knows someone with three arms) or only one hand (I also know someone born with only one hand). Mutations are widespread, we just don't see the long term effect of them because we don't live for millions of years. The human race has also stopped evolving in a positive direction, because now we can use technology to fix any failings our bodies may have, effectively eliminating natural selection.

[Amorphos]

quacky
thanks -most interesting!

chris uk

No, because all the other variants get eaten and die, because they’re not successful.

fossil evidence?

Random mutations aren’t that uncommon

of course, without them there would be no evolution.

thanks for all your answers, i think we can put this one to bed now.

[Tiwaz]

On original subject of this thread...

I recall seeing program where scientists had used computers to simulate this movement. Answer to such movements can be as simple as keeping an eye on 2-3 nearby fish and following their lead.

As for why this appears to be so confusingly fast?
Want to guess?

It's because those animals do not think. No, really! They live on pure reactions. If one fish notices another fish turn tail, it will follow example immediately as a reflex.

When compared to humans, guy A turns and starts to run, guys B,C and D do not turn but try to look and understand why A started running. If we humans did not have such ability to think we could perform same feats. If you notice, this behaviour is seen in fish and birds, neither of species which are well known for their immense mental abilities.