Teaching tricks to spiders

During a recent discussion of spiders during the recording of episode 10 with Dr. B a few misconception about daddy longlegs (who are not spiders) came up: "There is an urban legend claiming that the harvestman is the most venomous spider in the world, only its fangs are too small to bite a human, and is thus not actually dangerous. This is untrue on several counts (see also cellar spider). Phalangids are not spiders, and none of the known species have venom glands or fangs, but rather chelicerae. The size of the jaws varies by species, but even those with relatively large jaws virtually never bite humans (or other large creatures), even in self-defense. The few known cases of actual bites did not involve envenomation, and had no lasting effects."

I have been looking recently into keeping a house spider as a pet, maybe a wolf spider, since they do not build nets. Part of the reason I want a spider was to see if I could teach it tricks. I'm a bit jaleous of kamel and his rat circus, so I was hoping to condition the spider using a laser pointer, to tell it where and when a meal was coming. We've all heard of Pavlov's experiment with dogs but few of us know about his work with slugs which was recently replicated to look at memory.

Interrestingly, a new paper in PLOS shows that it is indeed possible to condition insects: "this study, we investigated the effects of conditioning trials on the level of salivation. Untrained cockroaches exhibited salivary responses to sucrose solution applied to the mouth but not to peppermint or vanilla odor applied to an antenna. After differential conditioning trials in which an odor was paired with sucrose solution and another odor was presented without pairing with sucrose solution, sucrose-associated odor induced an increase in the level of salivation, but the odor presented alone did not. The conditioning effect lasted for one day after conditioning trials. This study demonstrates, for the first time, classical conditioning of salivation in species other than dogs and humans"

However I was disapointed to find out that in flea circus, they do not teach the tricks via conditioning, but rely on cheap tactics: "Chemicals such as camphor that repel fleas are placed on lightweight balls and the fleas kick them away, this makes the fleas look like they are juggling or playing football. A recent example of this is the Munich beer festival Floh Zirkus. Training fleas in this way simply shows off their natural talents and in no way harms the fleas. However there are historical reports of fleas glued to the base of the flea circus enclosure, instruments were then glued to the flea performers and the enclosure was heated. The fleas fought to escape giving the impression of fleas playing musical instruments"

So I'll keep you posted on that experiment...

Tooth Specialization

A summer student in our lab mentioned that in a course she learned that lemurs have specialized teeth for grooming. I searched for other examples of teeth evolved for something other than gripping and breaking down food, and the most obvious was snake fangs, a great example of evolution. It seems like the hollow syringe like fangs of venomous snakes evolved from grooved fangs that delivered less venomous poisons.