(bright music) - Welcome to "Science Pub," where we explore the dynamic and exciting scientific world around us.

I'm your host, Nancy Scales-Coddington, and this episode is all about spiders.

Whether you love them or you're going to love them, we have an exciting show on how spiders catch dinner using a variety of techniques to lure or invite their guests to dinner.

But how do they go about this delicate dance?

What senses do they use to capture their prey?

Some spiders are ground dwelling, while others build complicated and beautiful webs.

We're gonna learn how spiders listen to their impending dinner company and how they use their legs to capture their next meals.

Joining me is Dr. Charles Walcott, professor emeritus at Neurobiology and Behavior at Cornell University.

Dr. Walcott received his AB from Harvard and his PhD from Cornell.

He served on the faculties of Harvard, Tufts, and the State University of New York at Stony Brook before coming to Cornell as the director of the Laboratory of Ornithology in 1981.

He retired in June of 1995 to return to teaching and research where he taught introductory biology course for five years and served eight years as associate dean and then dean of the university faculty.

He then served as the university ombudsman, retiring at the end of last year.

In addition to research on the hearing of spiders, the navigational ability of homing pigeons, magnetoreception in bees, and vocal communications in loons, Dr. Walcott has taught undergraduate courses in animal behavior, human psychology, and evolution.

He's also participated in designing programs connecting the public and science.

He is no stranger to public media.

He spent time working at WGBH in Boston on several PBS programs including "Discovery," "Exploring Nature," a television series for in-school use, "The Elementary Science Curriculum," and "3-2-1 Contact."

Welcome, Dr. Walcott.

- Hi, Nancy, it's a great pleasure to be with you.

- Well, we are thrilled that you are here with us this evening, and I would just love to talk to you about your early days working at WGBH.

I mean, this was even before "NOVA" was created.

What was that like?

- Oh, it was way before "NOVA" was created.

It was back in 1955 when WGBH TV first came on the air, and one of my friends was asked to do a program in natural history, and I had worked with her in the summer before at Wildwood nature camp.

And so she asked me to look at what she did.

And she was talking about tree frogs, and you could see, well, the camera could get in just about as close as it is to me now, and you could see that when she held up her hand that there was a little black smudge there, which presumably was a frog, but you couldn't really be sure.

And the problem was that the cameras simply couldn't get close enough.

And so I had an adapter made so I could use all my Leica lenses on the camera, and that's how we began.

And we were then able to show the suction cups on the frog's feet and fill the screen with it.

So it was a very exciting time.

And then we finally got some money the second year, when I was just graduating, to do some film so that we could go out in the field.

And we were spending some time up in New Hampshire, and as I walked past one of the barns which had horses in it, I noticed that there was a spider just beginning to spin its web right at the entrance to the barn.

And it was one of those things where the sun was right on the web so you could see the silk strands against the dark interior of the barn, and so I just began to photograph it, and it turned into about a half-hour film of a spider spinning its web.

And that spider was, of course, Charlotte, as in E.B.

White's book "Charlotte's Web."

And there it is, there's Charlotte down before the pig, and there is Charlotte's web on the right.

And it's a beautiful but rather complicated kind of structure.

You'll see that it has anchor lines that go out.

It has a series of radii which come into the center of the web, and then it has the spiral, and the spiral is what enables it to catch insects because it's sticky.

And so when an insect hits that, it tends to stick.

And if we look at a picture of a real spider's web, a real orb-web spider, you can see there it is with a spider sitting in the middle of the web, and you can see the sticky spiral around the edges.

Then when I went to graduate school, I was very interested in the spiderweb spinning, 'cause somebody had just shown that if you feed spider's various drugs, in particular, if you feed them LSD, you get a better web than normal, and that seemed an extraordinary state of affairs, and I was curious as to what was going on.

And so I went and caught a whole lot of web spiders and set them up in frames to do their web spinning.

And what I noticed, interestingly enough, was that their legs are very much involved in building the web.

And if you look closely at a spider who's spinning a web, as in the next slide, you'll see that their legs are playing a very important role in gauging the distance.

And if you look, you can see that the distance is really very uniform across there.

And so I was interested in what sense organs there were in the spider's leg.

And so I talked with my boss, Bill Vander Clute, who was a professor at Cornell and my supervisor, and he said, "Sure, I think I'll show you how to do that, and we have the electronics right here doing it."

And though I didn't want to use any of my beautiful orb-web spiders, so I went and caught some spiders from one of the neighboring buildings that make these little messy webs up in the corner.

And we bought them in and we tried to record electrically from the legs so that we could see what kind of sense organs there were.

And what you do is basically you tap into the nerve, and you record the electrical nerve impulses that are coming down the leg nerve, and then it would, if the spider were there, be going into the spider.

And so Bill and I spent the afternoon doing this, and we got nowhere, nothing worked at all.

- Oh, that's not good.

Wait, so Dr. Walcott, are you telling me that, you know, like we have senses with our eyes and our ears, the spiders also have these kinds of senses and their ears are in their legs?

- Well, we didn't know what they had in their legs.

That was the whole question.

I had no idea what kind of sense organs there were.

Obviously something to do with stretch, because as you watch it spinning the web, it's able to gauge the position very accurately somehow or other.

So there must be something that's detecting that.

And but that afternoon, really nothing happened.

And then Bill went home for dinner.

And being a graduate student, I continued to play, and being an ignorant graduate student, I simply put an electrode at each end of the spider's leg, one at the base and one at the tip.

And at that point, the Cornell chimes began to ring, as they do at about 6:00 PM, and by gosh, there on the oscilloscope were action potentials that corresponded to the chimes that were being played, and I was astonished to say the least.

It was very impressive.

And here, for example, is the kind of thing that you see.

This is an oscilloscope, and what it's doing is simply measuring the output of a, in this case, a jumping spider's brain.

And you can see what action potentials look like as that progresses.

- [Nancy] So what is an action potential?

- An action potential is the message that a nerve sends to the central nervous system.

And here is a photograph of the output of a spider leg, and you can see these little vertical lines.

Those are action potentials.

They are a message from a nerve cell in the spider's leg that goes up to the spider's brain to tell them, "Fly ahead," or "a fly in your web" or whatever.

And one of the things that's interesting is if you look at that picture, you'll see that there are some spikes that are big, and there are others that are small, and it turns out that the spider is able to tell one frequency from another.

And the little spikes tend to be high-frequency receptors.

The big spikes tend to be lower-frequency receptors.

So by recording this electrical activity, one could learn a lot about the sense organ.

- So is there a difference between those frequencies?

As the spider's taking in that information, does one mean more than the other?

- Well, I don't know, to be quite honest about it.

We know that different frequencies have a different effect, but we don't know exactly what the spider does with that.

I thought at one point that it was a question of telling the difference between a fly in the web, which is delicious, or a bee in the web, which makes a much higher-frequency sound, which might not be quite so delicious.

That is, it might be a bit of a hazard to the spider.

But it turns out that that's not the case, that everybody is treated equally.

The spider is an equal opportunity receiver of insects, as far as I can tell.

- So everybody's delicious, then.

(laughs) - Everybody is welcome, yes.

So that was what we learned about this.

And then the great question, of course, is well, where whereabouts is the detector?

Where is the ear, as it were?

And obviously it's on the leg because that's what we had.

The rest of the spider isn't there.

It's just the leg.

And so by a little judicious pruning, we were able to find that down towards the end of the leg at what is called the tarsal-metatarsal joint, that is, it's the next-end segment of the spider's leg, there were a bunch of little slits, as if you had a saw cut, and here they are.

It's right next to the joint, and you can see that there are little slits, and it's the compression of those little slits that is acting like the ear.

In other words, the whole end of the spider's leg wiggles, and it's as if you took an iron pipe and made a bunch of saw cuts in it, and you move the end of the pipe.

The little saw cuts open and close as the pipe moves.

And that's exactly what's going on here.

Those little slits open and close as the spider's leg moves, and that is their ear.

And what's interesting about it is you look at a really close-up picture taken with the electron microscope, you can see much more in the way of detail, and each one of those little slits is equipped with a nerve cell.

And you can see that one of them is a diagram here and is that big thing up at the top left of your screen is the nerve cell, and it sends a process into those little slits.

And when the slit compresses, it causes that nerve to activate and to generate one of those action potentials which travels down then the nerve to the spider's brain.

And in this case, it travels down to our electrode, and we are able to to detect it.

And what's interesting is that spiders are full of these kinds of what are called lyriform organs, but the only ones that seem to be sensitive to sound are those on the end, toward the end of the leg, and they're very sensitive indeed.

- So Dr. Walcott, there is lyriform organs on the legs, but the ones near the end are the ones really sensing what's for dinner.

- That's right, that's correct, and they are the ones that, or detect the sound.

And what's interesting is, of course, the end of the leg moves an infinitesimal amount.

It's not as if it's a big wobble.

It's a very, very, very small movement, and that is detected by these spiders.

So then the question was, of course, well, is this true of other kinds of spiders as as well?

And we tried a number of different kinds of spiders, and it turns out that it's not true of most spiders.

The orb-web spiders, for example.

they have those same organs down at the end of their leg, but they're much less sensitive to airborne sound, though it has just been shown by a group at State University of New York at Binghamton, Ron Miles, Dr.

Miles, and Dr. Hoy here at Cornell, that the web itself acts as an enormous eardrum basically.

And so these spiders, when they're taken off the web, are not very sensitive to sound, but when you put them on the web, they use the web as a great big, it's like cupping your hands behind your ear almost, as a way of the web itself acts really as kind of a giant ear.

And one of the things we were concerned about is, well, it seems funny that Charlotte is less sensitive, but if you think about it and looked at the picture of that spider in its web, what you see is that it has its eight legs on all the radii that are, and so if an insect hits anyplace, there's going to be almost a direct line of communication via the silk threads to the spider's leg.

Whereas the spider that I work on is a messy-web spider that does not spin a beautiful web.

It spins a kind of messy cobweb in the corner of one's window.

And and here it is, this is just a plain old house spider.

But you can see the web is kind of irregular and messy.

And I wondered whether that was the reason that these spiders are so sensitive, because they may not be sitting on the right strand of silk to get the vibration.

They may have to get it through the air.

And indeed, you can play sounds to these spiders, and they will come and attack a sound on the order of 100 to 500 cycles per second that is played to them.

But if you play them a sound of over 1,000 cycles per second, they simply drop from their web and disappear.

And what that's all about, I really have no idea.

It suggests to me that there must be some predator that has a signal that's at that high frequency, whether it's the chirp of little birds or what, I don't have a clue.

- Yeah, that does sound, it gets too loud and they, and they leave.

We do have a couple questions.

So can, and you did talk a little bit about this, so can the spiders detect sounds in their legs from the air, or does it have to go through the web?

- They can detect it.

The little messy-web spiders that I talked about can detect it directly from the air, whereas I think the orb-web spiders are like Charlotte, probably have to have the web as kind of an amplifier, as it were.

But there's no question that the little messy-web spiders can detect it from the air without any web whatever.

- Do you think that that has any correlation to the design of the webs that each one of those spiders makes respectively?

- Yeah, that's what I think.

I think that the orb web acts, as I say, as this giant ear, whereas the messy web, it doesn't do that at all, and that's why the spider has to be more sensitive.

This is another example of a spider that spins a web.

This is a so-called, not a house spider, but a sheet-web spinner, and it spins those big webs that you see on misty days in the grass.

And you'll notice that there's a little hole on one side of the web, usually, on one side of this big sheet web, and that's where the spider hides.

And you can see it here on the left.

This was taken in our garage, and the light shining through the window shows the spider inside of his little silken tunnel.

And it's sitting in there and it's paying attention, I think, to the vibration of the web, because we've tried these spiders, and they're not very sensitive to airborne sound.

And yet by standing on the web itself, they are able to detect the vibrations of insects that are trying to traverse their silken, their great big silken sheet that's outside.

- So I have a question on, so they're hearing these vibrations in their legs.

Do you think that they're also feeling that happen?

So once, you know, a fly comes into that web, and it's making quite a bit of movement happening there, is there any research that shows that the hearing is what triggers them, or is it the movement that might trigger them?

- I'm sure it's both, and we're sure of that because we can play sounds through a little loudspeaker to the spider, and they will come rushing off, try and attack the loudspeaker, and that's clearly sound.

On the other hand, there's a little video clip somewhere here that shows what happens when an insect gets tangled.

This is a, one of those house spiders sitting in its web, and I regret to say I added this insect to the web, and you can see that there's no question that there's vibration traveling through that web to the spider, and it runs down and then attacks the insect with silk, and then it will bite it and eventually go back.

So I'm sure it's like all these things.

It's not just one thing.

It's a combination of different cues that the animal uses.

- [Nancy] Absolutely, so do spiders, do different spiders have certain prey that they prefer?

- Well, I think they probably do.

I think that they're all, they typically are all mostly insects that are eaten of one sort or another.

But there are many different kinds of spiders.

There are the wolf spiders, which are on the ground.

They're ground dwellers, and they appear to be relatively insensitive to sound.

I think they're probably visual hunters mostly, not necessarily paying attention to sound.

Then there are the jumping spiders, which are fascinating little spiders, which move around.

Again, I think they're highly visual, and that is how they hunt.

But it turns out, well, I think actually we have a picture of a jumping spider.

Here's a jumping spider, and you'll notice one of the things about it is it has very substantial eyes, has two big eyes in the front and two smaller eyes.

And here is a fly being offered on the end of a silk thread, and it's clear that the spider is attacking that using visual cues.

But beyond that, it turns out that they are, they are very visual, but they're also very fast.

They're extraordinarily quick in their catching of flies.

And there's a little film that's slowed down here, which will give you a sense of that.

There's a fly on it, and the spider is stalking it, and got it.

- [Nancy] That was fast.

- [Dr. Walcott] And that's fast, and that's in real time.

But now let's look at the same thing slowed way, way, way, way down.

And that was in real time.

Here it is slowed down, and you can get a sense of the whole process.

Come on, spider!

- [Nancy] This is like spider going to the grocery store.

- [Dr. Walcott] There it goes!

- [Nancy] Now, that was a big jump on the back feet there.

- [Dr. Walcott] (laughs) And it's got it.

That just gives you a sense of the extraordinary, there's another one at real speed, and in this case the fly is tethered so it can't escape, poor thing.

(Nancy laughs) There it goes, there goes the spider.

- With significant force from its back legs to propel forward.

- It really does, yes.

Well, that is, after all, they are jumping spiders.

And so Gil Menda, who worked in Ron Hoy's lab here at Cornell, was interested in their visual system.

And so he put electrodes in the spider's brain and was able to record the effect of these visual, a variety of visual stimuli.

But what he noticed was really quite surprising, which was that when people walked along the corridor outside his laboratory, the spider responded with action potentials in the brain.

And that must have meaned that the spider somehow or other detects the sound that people were making or the vibration through the floor.

And so after a lot of exploration, what Gil and Ron found is that the spiders, these particular jumping spiders, are detecting sounds, but they're not using the lyriform organs, which they have, but they're not adjusted for sound.

They're using whiskers, very thin, tiny whiskers on their leg, and here's a close-up of those.

They're called trichobothria, and they vibrate with sound, and that's how this particular species of spider manages to detect sounds.

And it is sensitive to sounds from about 100 to about 300 or so cycles per second, a funny kind of range until Gil figured out that there is a wasp that prays on these spiders, grabbing them and taking them home to feed the young wasp larvae and that the wing-beat frequency of that wasp is, guess what, right in the middle.

It's about 150 cycles per second, right in the middle of this spider's sensitivity range.

So in this case, the sense organ is not for detecting prey.

The sense organ is for detecting being preyed on by wasps.

And if you meet one of these little jumping spiders walking along and you play it a tone of about 150 cycles per second, it stops dead and doesn't move a muscle until the sound disappears, and then off it goes.

So it's an interesting, again, a kind of interesting story.

- But interesting how varied the spiders look compared to each other.

So like the jumping spider has all of those hairs on it.

It's much, it appears to have many more hairs than the Charlotte spider that we saw when we first started the talk.

- You know, that's true, the hairs are different.

These are little thin, wispy hairs.

They're not the furry things that you find on wolf spiders and to some extent on Charlotte.

So they're different.

Now, I don't know whether Charlotte may not have some trichobothria, too, it could well be.

I haven't looked, so I don't know.

It's one of these things about spiders that there are people who are exploring them, but still, compared to other animals, I think we know relatively little about how it is that they detect the world around them.

- We had a question about one of the orb spider images asking about the function of the open web area near the middle of the web, so very much like the Charlotte's web.

Exactly, just like this one.

So you have the radii in the center.

Then you have a little bit of a gap before the web picks up again.

Is there a reason for that?

- I don't know.

I have no idea.

I was looking at that and wondering about it myself.

I think it's more pronounced in this spider than it is in some others, but I just don't know.

Maybe a it's pad where the spider tries to sit, and some spiders make a very dense strand of silk in there called a cribellum, I believe, which I think it kind of hides behind so that it isn't quite as obvious maybe to birds who would like to eat them.

But I don't know, good question.

- Well, keep those questions coming.

So yeah, it's interesting how the spiders actually hear and how they hear through the web and how they're hearing through the air.

So the funnel-web spiders, we talked a little bit about them.

So with them, you said that this is mostly hearing through the air is how they're actually.

- [Dr. Walcott] No, I don't think so.

I think it's through the web.

- [Nancy] This one's through the web.

- [Dr. Walcott] Because the funnel web, if you look at them, is a great big sheet of silk, and I see it normally when there's been dew on the grass.

You see these great big sheets of web, and then you look carefully, and you'll see off to one corner of it is kind of a tunnel.

And that's where the spider is hiding, in that tunnel.

And when you vibrate the web with a tuning fork or by dropping an insect into it, it comes rushing out of the tunnel and grabs the insect.

- Do you have to go hunting for all these insects that you're feeding the spiders?

(both laughing) - Well, sure.

You gotta feed 'em something so you can get that behavior and find out what's going on.

Well, I think then, the final thing I would like to share with everybody is a really extraordinary spider that a student in Ron Hoy's lab at Cornell has been working on, and it's found in the Southern United States.

It's a nocturnal spider.

It hides in palm fronds during the day, and then at night, it sets about hunting insects, and it has really quite extraordinary capabilities.

If you look at it, it has these enormous eyes which are very, very sensitive to light, and like other spiders, it spins a web all right, but it spins a little small web that it holds with its four front feet like a net, as if you're gonna have an insect net to catch things.

And these spiders manage to catch prey that is crawling along the ground, and they manage to catch insects that are flying through the air by plopping this little net over them.

And they're really quite extraordinary beasts.

And I have a little film, which just will give you a short impression of how these spiders work.

(suspenseful music) - [Jay] They have the biggest eyes of any spider.

They're 2,000 times more sensitive to light than humans are.

They make this little rectangular net, and they dangle above the ground or a leaf, and they'll throw it down or actually hit things out of the air, which is, it's incredible to see.

(eerie music) - Now, that's the work of Jay Stafstrom, who is now a post-doctoral associate in Ron Hoy's lab.

And what he has found is that these animals, these spiders are visual hunters, and they're able to hunt at night in very, very low light levels.

But if you make the, you cover up their eyes, which you can do with little plastic coverings, it turns out that the spiders can no longer catch insects from the ground, but they have no problem whatever catching aerial insects, flying insects with that little web.

And this they do by hearing, and these spiders, like the spiders I worked on, are incredibly sensitive to airborne sound, and they're using that in addition to their visual system to catch their prey.

And I just think it's a wonderful example of how a variety of sense organs are all concentrated on the same thing, which is finding dinner.

(laughs) And dinner in these cases is insects.

- How does the net-casting spider, how does it actually let go of the web?

- I don't think it lets go of the web.

It kind of wraps it around the prey, and so the prey is now caught in this little tiny web that the spider has made, and then the spider goes obviously and bites it and wraps it up properly and has it for dinner or breakfast or lunch.

- That's a meal to go then.

(laughs) A meal on the go.

- It's an extraordinary story.

And what's again remarkable is how very fast these spiders are in their actions.

That is, that movie that you saw is taken at 8,000 frames per second, whereas the television camera is running at about 30 frames per second.

So it's slowed down many, many, many times so that you can get a sense of how fast the whole thing really is.

- Yeah, that's really impressive.

How did you come up with designing basically spider goggles and getting them on all eight eyes of these net-casting spiders?

- I'm not quite clear on your question.

Could you repeat?

I'm sorry.

- Yeah, sure, so you had talked about how the work that Jay and Ron are doing, that they put coverings over the eyes of the spider.

How did they do that?

- Yes.

Well, I don't know the details, but basically they made a little hood, fundamentally, that you could put over the eyes that prevented the spiders from seeing with those great enormous big eyes, which is what they used apparently for catching insects on the ground.

And the nice thing about the way Jay did it was you could take it off when you were done the experiment, so you didn't harm the spider.

But what it did do was to show that the catching of insects out of the air doesn't depend on a sense of vision or at least not vision with those big eyes because there are also obviously the small eyes, and that probably it's the sound coupled with perhaps or the small-eye vision that enables them to catch the insects from the air.

- Yeah, that's really impressive.

We have some questions about webs and web designs, one of them being, you know, talking about how sticky the spiderwebs are.

How does the spider not get stuck in its own web?

- That's a very good question.

The spider begins by putting in the radii, if you're talking about an orb-web spider, and the radii are not sticky silk there.

They're just plain, ordinary spider silk.

It then spins a very wide-spaced spiral on the radii, and which you don't see here because this is the finished spiral.

And what happens is the spider then goes to the outside of the web and begins to spin the sticky spiral holding onto the radii and to the non-sticky spiral, which it removes as it goes.

So it ends up then with this sticky silk as you see here.

Why the spider doesn't get stuck to it is a good question, and I don't have a very good answer.

I can certainly report that they don't.

Their feet are with little claws and so on.

And I simply do not know why they don't themselves get stuck in the web.

It's a good question.

- That'll be the next- - And I think the answer's known, I just don't happen to know it.

- (laughs) The next bit of research.

So sticking with the webs, we have a question on, so a particular spider makes a certain type of web.

Will that web look the same throughout its lifetime, or will the web actually start to change shape as the spider ages?

- Yeah, well, first off, the spider by and large makes a new web every night.

They get brutalized by wind, and leaves get caught in it, and so the web ends up kind of raggedy after a day or so, and so the spider typically spins a new one almost every day.

And as the spider gets bigger and older, it tends to make a somewhat bigger web, not too surprisingly, but they're much the same.

The general architecture of the web, for orb-web spiders, is pretty much the same.

Some have, as I say, a stripe of silk going up the middle of the web, and it's called a cribellum, and others have other features of the web.

So there are species-specific differences.

But the orb webs are all pretty much, I would say, the same.

- Thank you, so there has been lots of information in the news lately about just the overall decline in insect populations, you know, and when you and I first started talking about doing this talk, you had mentioned, you know, not being able to find some spiders to find images.

So is there data on spider populations declining?

- Not that I know of.

My impression is that they are very much in decline.

I used to be able to walk next door to Goldwin Smith at Cornell, which is a big old building, and there would be four or five spiders in every window, you know, in the corners there.

And when I most recently went looking this fall, I found none, zero, zip of the spiders that I worked on.

There were a number of sheet-web spiders, but there were none of the common house spiders that they usually are.

Now, this one is called Pholcus, which is a cellar spider.

Again, it's very sensitive to airborne sound, lives in a very messy web, typically in people's basements, and I have no idea whether their population is increasing or decreasing.

A lot of my academic colleagues say, "I have a basement full of those things if you want some."

So I take it that they're fairly common.

But in general, my impression is that the insect population has dropped dramatically, at least here in the Ithaca area, and that therefore the number of spiders has also declined tremendously.

And I used to be able to find them in the windows of my house here.

The little video I showed you of a spider catching that beetle or whatever was taken right out my back door here, and this year when I went looking, I couldn't find a single one, and so I couldn't improve on that rather poor video.

- What do you think is causing this decline?

- Well, I don't know.

That you'd have to ask the entomologists, but I have a suspicion that it's the use of insecticides probably increasing to some degree, but I really don't know.

And so I really shouldn't say, I just don't know.

- We actually have to go.

- But it's fairly dramatic.

I was talking with one of my colleagues who said that as he drove between here and Boston, he'd have to stop and clean off his windshield of dead bugs, and in recent years, that hadn't been a problem at all.

And that's bad news for the spiders, not perhaps bad news for the windshield.

- (laughs) It's all in the perspective, isn't it?

- Yes, it is.

Yes, it is.

- Is there something that, you know, we can do to help the spiders?

You know, is there a way we can maintain habitat for them besides, you know, just giving up on dusting?

(laughs) - No, I don't think there's much we can do other than I think be interested in them.

They're a fascinating group of animals, all sorts of interesting adaptations.

I think they have not been studied as much as many insects, and so we have a lot to learn about how spiders make a living and what kind of perils they face in the form of predaceous wasps and hungry nuthatches and chickadees and all the various predators who lurk around looking for insects or spiders to eat.

So they're a really, I think, a fascinating group of, fascinating group of animals.

- So we have a question on spider bites.

You know, is there a way to tell if you've been bit by a spider versus something else?

- That's a good question, and I don't know the answer to it.

Fortunately, most spiders don't bite people.

The black widow is an exception, and that is occasionally found around here.

Another spider called brown recluse is around in people's houses.

It's a little, small brown spider, and its bite is really very painful and so on.

But most spiders don't bite people, though the thought of one of those great big wolf spiders in the bathtub before you try to climb in is not very appealing.

They're probably pretty harmless, though personally, I remove them and take them outdoors.

- (laughs) That's probably a good place for them.

We have a question about an arrow-shaped micrathena, and somebody said their son saw one at Chenango Valley State Park, which is not too far here from Ithaca, and they weren't aware that they had existed.

Are you familiar with that?

- I'm sorry, you're breaking up a little bit.

Could you repeat that question?

- Sure, are you familiar with the arrow-shaped, is it micrathena spider?

- No, no, I'm not at all.

Again, it's one of those things.

I've mostly specialized in just looking at this one spider and one sense organ.

So I am not competent to talk about all spiders in general.

There are a fascinating variety.

There are the social spiders that hang out in Australia, which do all sorts of interesting things as a group.

And Linda Rayor at Cornell is the great expert on the social spiders, and I know, I regret to say, nothing whatever about them other than they're clearly interesting.

And I've mostly played with the ones that I've encountered around here in Ithaca or New Hampshire or whatever.

- So making a web every single night uses a lot of resources from the spiders.

Do they ever recycle the silk from another web?

Are they able to do that?

- Yeah, yes, my impression is that they do.

I don't know, again, I don't know that much about it, but my sense is that spiders in some way gather up some of the silk, and whether they eat it or whether they just remove it, I really don't know.

But you're absolutely right.

It must take a substantial investment to make one of those webs, and some of them are really very large indeed and represent, you know, a quite substantial amount of protein.

That's what the silk is mostly made of, of one sort or another.

And the spiders obviously have to invest in catching their dinner, and you know, that's kind of important.

I mean, no dinner, no web, but you kind have to have the web first before you get the dinner.

So I'm sure that it's a major investment.

- Yeah, you run into a little bit of a catch-22 there.

Someone had a question on when you're setting up your videos, which are absolutely amazing, how difficult is it to tether the fly on one side and get that to stay there while setting up your spider on the other, jumping spider, and making that experiment happen?

- Well, my guess, though I don't know, I wasn't there when those high-speed movies were taken.

My guess is that that is a deceased fly or at best one that is carefully tethered in place, and one would do that perhaps by anesthetizing the fly in carbon dioxide and then putting a little tether on it and so that it can't escape.

Carbon dioxide is a wonderful insect anesthetic, and it wears off quite quickly, and the insects don't seem to be any the worse for having undergone it.

And so my guess is that that's a tethered fly, not one that is just free to fly away.

- Sure, I'm sure keeping that spider in place is pretty tricky as well.

- Yes, I'm sure persuading the spider to stay there and then jump when you want it to while you could see the video.

But nowadays, of course, it's all done with video, and so you don't have to worry about the film.

In the old days, you used to have to start the film because you wanted to catch the whole behavior, and you might run through a whole roll of film with nothing.

And so then you throw that one away and start with a new one, and it was expensive.

- Indeed.

- And now with video, at least it's all electronic.

- Yeah, now you can take as much video as you want.

You don't have to worry about purchasing the film, which is very expensive.

I know that you have targeted spiders that you work on, but we have a question.

Is there an easy way to spot poisonous spiders?

So for example, like with snakes, if they have that triangular head, right, you probably wanna stay away from them.

Is there something similar with spiders?

- No, there really isn't.

I think the thing to remember is that most spiders are totally harmless and have much more to fear from you than you from them.

And there are a few of these exceptions, like the black widow, which is black with kind of a red hourglass shape on its abdomen, as it were, and the brown recluse, which is just a kind of amorphous little brown spider.

And so I treat all of them with respect and keep my fingers out until I know what kind of spider I'm dealing with.

But I think by and large, as a group, they're relatively harmless, to people, not to bugs.

- (laughs) Well put.

Where do you stand on having spiders as pets?

Is this a good idea or not?

- Oh, I don't know.

I think people can have a whole variety of different kinds of pets, and a lot of people apparently have tarantulas as pets, and they are very interesting spiders.

I don't know much about them except that Professor Barth, who is the great expert on tarantulas, says they are totally deaf and indeed claimed that my research was all artifacts because his spiders were totally deaf.

And I'm not even convinced that he's correct about that.

But who knows?

They're a very interesting animal, and they come in a whole lot of different flavors.

But they're all ground dwelling, or some of them are, I think a few of them are in trees and so on, but they're mostly ground dwelling.

- That's surprising that they are deaf, interesting.

- Yes, well, you know, but that's what he claims.

And I have not tried one, except I have tried some of the legs, and I can agree with him that I could get no response out of the legs to sound.

Vibration, yes, but sound, no.

And so, but you know, you can't always be sure of that.

Maybe they have whiskers like the jumping spiders and are using that to detect sounds.

On the other hand, I think Professor Barth has spent years studying them, and I think if they were sensitive to sound, he would know it by now.

- (laughs) Well, that's the wonderful thing about science is you continue to learn, and as technology improves, we continue to learn even more.

- Exactly, and that's what's fun about it, you know?

You may think you know everything there is to know about some little animal or some spider, and the more you look at it, the more you study it, the more there is to learn.

So it's a never-ending process.

- That is true, so Dr. Walcott, what is next for you?

What do you have on the horizon?

- Well, I don't know what I'm going to do.

Doing a little playing with these spiders.

I would love to be able to record from their central nervous system, from their brain to see how they coordinate their eight legs.

Because, you know, here, if you're sitting on the web and you have eight legs, which they do, how do you coordinate the information and determine the direction to the sound?

I would love to know more about that.

But otherwise, I'm enjoying being retired and making sure the fields get mowed and the garden gets planted and the vegetables get harvested.

- Well, that sounds pretty spectacular.

- Oh, it's great fun.

It's been a wonderful time.

- Well, thank you so much for spending the evening with us, Dr. Charles Walcott.

We greatly appreciate your expertise and sharing your research with us.

- Well, it's been great fun, and thank you for having me.

- I wanna thank our WSKG team tonight, our director, Alyssa Micha, our chat moderator, Kristine Kieswer.

Support for "Science Pub" is provided by the Robert F. Schumann Foundation and from viewers like you.

I'm your host, Nancy Scales-Coddington.

Thank you for joining us.

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