How do they hunt?
- Thread starter boosh96
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I believe that they detect the smallest of vibrations made from their prey with their dense coat of bristles and silken draglines/sheets they may have layed down.
Personally, saying they hunt wouldn't feel right to me. They are more ambush predators, grabbing things that wander into their area, rather than pursuing and tracking down prey.
Personally, saying they hunt wouldn't feel right to me. They are more ambush predators, grabbing things that wander into their area, rather than pursuing and tracking down prey.
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Wrong. Their bodies are carpeted with chemosensitive bristles that provide something analogous to a combined sense of taste and smell. And, these are particularly dense on their pedipalps and front legs.
Again, wrong. Most of those bristles that are not chemosensors are extremely sensitive to sound, especially in the lower frequencies, and courser vibrations like those produced by moving prey. And, there are other, enigmatic structures buried among those bristles whose function is obscure to us at best. Tarantulas have an uncanny sense of touch and vibration.
While this little topic is not so cut and dried as your first two, your impression still isn't exactly correct. Many tarantulas, especially the arboreals, apparently have pretty good vision, and have been observed turning to follow moving prey on a neighboring branch for instance. Specifically what they see is still being debated, but that they do see is pretty much accepted. Terrestrial tarantulas, on the other hand, have little use for eyesight (after all, how interesting is a burrow's walls?), but we've had some terrestrial, North American species and several tropical American species turn to face us as we moved. The exact mechanism here is open to some question because I'm not entirely sure that they were responding to sight rather than to vibration, but the possibility that eyesight was at least dominant is strongly suggested by the circumstances (e.g., in my living room, with the tarantula's cage on a carpeted floor and me sitting in an easy chair).
That brings up another tactile sense that you may not appreciate. A lot of those bristles are capable of sensing minute air movements, the gentlest of breezes if you wish. A passing prey might easily merely disturb the air or produce very minute currents that the tarantula can sense.
"Hunt as effectively as they do" does not go deeply enough. Most terrestrial tarantulas are ambush predators. They wait in or near the mouths of their burrows for passing prey. And they almost surely detect that prey by means of vibrations set up in, and transmitted by the soil as the prey moves. The tarantula senses these vibrations mostly through the tips of its pedipalps and front legs, less so with the more rear legs. And hypothetically, it is able to triangulate the position of the prey by correlating those vibrations much the same way that you can triangulate the position of a sound source based on a cross correlation between what each of your ears detect.
A few terrestrial tarantulas actually leave their burrows and prowl the neighborhood for food. I think that I remember either Sam Marshall or Rick C. West stating that they observed one of the species of the genus Theraphosa doing so, putatively looking for small frogs on the forest floor after dark. Hypothetically (since the phenomenon wasn't closely studied), we can say that they might be sensing the "smell" of a frog on the forest litter, and triangulating it's path across the forest floor based on four or so extremely sensitive sets of chemoreceptors, one set fairly carpeting the ends of each of its front appendages. This would be especially efficient because these sets of chemoreceptors would have a spread of up to perhaps 6" to 8", sweeping ahead and around it as the tarantula slowly moved across the terrain. (The arachnid equivalent of a bloodhound!)
When the tarantula came close enough to the frog (or other prey) its vibration sensors on the ends of those same appendages would gradually assume dominance, and as the frog moved or perhaps even breathed, would pick up and triangulate its position relative to the tarantula to within a very small margin of error. As soon as the tarantula had stealthily moved into position all that would be required is a sudden attack with fangs bared and the frog becomes the entree in total darkness. It might never know what hit it!
And of course, the arboreals with better than average eyesight would merely add that facility to their hunting armamentarium.
We do not appreciate the complexity and depth of these creatures. They are not merely "dumb, primitive bugs." Their nervous systems are far advanced compared to most other arthropods, and we barely understand the basics of their anatomy. Their predecessors and they have had more than half a billion years to develop, refine and perfect a most exquisite anatomy, physiology, lifestyle, and set of habit patterns, features that we can only begin to appreciate in our juvenile ignorance.
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Fantastic post Pikaia! A tarantula's incredibly complex sensory system is, in my opinion, one of the most amazing and interesting things about these spiders. Thanks for the primer on it!
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The Tarantulas Keeper's Guide is full of awesome information. I love it! Extremely interesting just to read and useful if you're going to own tarantulas. Hundreds of pages of awe inspiring information!
Just make sure you get the 2009 version. I accidentally got the 1998 version and although it was a good read, it wasn't up to date. I have since bought the new version.---------- Post added 01-14-2012 at 02:42 PM ----------
Also, you can search Pikaia in the search box. His posts are always so extremely informative.
Simon83
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I always find it kind of odd that tarantula's can't really see that well considering they have so many eyes.
kanito107
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I'm telling you pikas is god. Listen to him he know his tarantulas.
Great work
Great work
web eviction
Arachnolord
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+1 great post pikaia
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And I am impressed with the fact that so many people don't think very well, even though we have one of the most highly developed brains on the planet. The tarantulas apparently evolved just far enough to get the job done, maybe even done well, then they sort of stopped evolving.
We on the other hand, are apparently having big problems just trying to keep our respective acts together in spite of our magnificent brains. I keep thinking, "Surely we should be able to do better." Oh, well. At least the majority of the members of this forum seem to have a clear advantage over all the other members of our species. We've more or less all failed to develop, or have overcome, any real or potential fear of things with 8 legs. Even to the point of forgetting how unusual that really is!
[highlight]'Just think how stupid the average person is, then realize that half of them are even stupider!'
--George Carlin[/highlight]
---------- Post added 01-14-2012 at 11:41 PM ----------
And thank you, one and all, for your compliments. We aims to please.
Tarantulas and base jumping don't mix.
-- David Desoer
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'Just think how stupid the average person is, then realize that half of them are even stupider!'
--George Carlin
Love It!!! He's one of my favorite comedians!
--George Carlin
Love It!!! He's one of my favorite comedians!
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+1 pikaia well said...!! Tarantulas are by no means well studied...
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Most of my collection consists of N, S and Central American terrestrial species. I, too, have observed some of them seeming to 'follow' movement outside their enclosures.
Love George Carlin!
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Sorry? what do you mean by "average stupid bug"? each and every creature has it's very own special features that we'll surely appreciate, if we ever see them. most of the people think of Ts and spiders as just some stupid bugs...but most of us believe that it's wrong because we found some of those appreciating features of them. See the world better
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I've never quite understood why humans are so keen to judge animals based on intelligence, like that's the most important factor. I mean, it makes sense, since intelligence is the one thing going for us. But I, as well as most of the people on this forum I'm sure, don't place "intelligence" as a high priority when choosing the animals we like - there are other aspects that can just as easily be appreciated, like incredible sensory systems and whatnot. I'd much rather have tarantulas and reptiles than parrots and monkeys.
(I hope it doesn't annoy anyone that I bumped this up - this thread just intrigued me.)
(I hope it doesn't annoy anyone that I bumped this up - this thread just intrigued me.)
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True! I always wanted a monkey, until I realized they may be smart enough to plot revenge. Not saying I will deserve revenge, BUT, I don't know what would constitute revenge in a monkey's mind. Maybe I didn't feed it right when I got up or maybe I was rude to it because I had a bad day. Next thing I know, poop everywhere! No thanks.
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It wasn't that old. Bump away!
---------- Post added 02-05-2012 at 08:36 AM ----------
Actual officer's comment taken off a police car dash-cam:
"Fair? You want me to be fair? Listen, fair is a place where you go to ride on rides, eat cotton candy and corn dogs, and step in monkey poop."
:biggrin: