Ask urodacus!


#1021

Collection methods for spiders vary depending on the size of the spider, its readiness to release venom, and the amount of venom produced. With smaller spiders, like black widows, etc, venom is collected by jimi’s method (collect spiders, dissect out the venom glands, purify venom after removing as much of the outside of the gland as possibe). For many larger spiders (typically ground dwelling spiders like trap-doors or tarantulas, which have downward-pointing fangs rather than inwards-pointing) one can actually milk them by holding the spider and ‘encouraging’ it to bite over the edge of a small vial, just like collecting venom from a snake.

Other spiders are way too dangerous to handle, like sydney funnel web spiders, but fortunately they are so aggressive that venom drips from their fangs when they are agitated. This can be collected using essentially a tiny vacuum cleaner (I used to use a fish tank air bubbler running in reverse connected to the end of a glass pipette with about 1 mm opening at the skinny end). The funnel web spider in its laboratory house comprised of a large plastic jar with potting soil rears up on its back legs, exposing the face and lashing out with front pair of legs, trying to grab onto something to bite. Just hold the pipette near the fangs and suck up the venom. Maybe 20-40 microlitres can be collected from a single big male that way.

Scorpions also vary in size, but are more difficult to get venom from. One method is to remove venom glands from scorpions collected from the field, but you may as well keep them in the lab and milk repeatedly, like I did. Some scorpions will release venom if handled (carefully!) but it is easier and more productive to use electrical stimulation of a trapped scorpion’s tail (the venom gland is in the bulb on the tip) to make the muscle contract and expel the venom. That can be repeated every few weeks. For the larger scorpions (like the big Thai ones, or African lethals with big stingers and small hands) lots of venom can be collected, like 0.5 mL, but for the smaller ones I studied more often (and usually with strong hands and correspondingly with less lethal venom), normally only 2-5 microliters are recovered each time, which made life difficult for someone studying venom.

People often say that the daddy long legs has the most potent venom of any spider, but that’s crap. For all we know, they MIGHT have dangerous venom, but they would make vanishingly small amounts, and have consequently never been studied. Also, from an evolutionary point of view, there is no reason that they would need to have strong venom, unlike the ground dwelling spiders that live for a long time on or in the ground and thus are under significant threat of predation from lizards, mice, etc.


#1022

That’s really fascinating and I mean that. How about getting the venom from sea creatures?


#1023

Sometimes easy, sometimes extremely tricky.

Some fish have poison glads in spines and fin rays, but these are tricky to collect. Often they just catch lots of that species and try to remove all the bits that aren’t poisonous. In other poisonous fish, the poison is internal, like in fugu (puffer fish) and the poison must be collected by chemical separation from the fat, for example. Fugu tend to be very poisonous in their organs, and careful removal of the fat around all organs means they van then be eaten.

many other fish and shellfish are poisonous by virtue of being infected with certain poison-producing bacteria. This is the case with much of the red tide toxins that render shellfish uneatable. Or they can eat many other smaller poisonous animals and concentrate poison in their own bodies that way, as with ciguatera. The poison in fugu is actually made by a commensal bacteria that infect the fish, and are passed on in eggs. Amazingly, the fugu poison (tetrodotoxin) is EXACTLY the same as the poison in blue-ringed octopus and in many other marine and terestrial animals, especially reef fish , shellfish, and some amphibians. It was thought to be made by the pufferfish, but later was shown to be made by one (or several related) bacteria that evolved to live very closely with their hosts.

Other stinging creatures in the sea have different poisons made entirely by themselves. Cone shells, about 200 species thereof, all make venom for rapidly immobilising fish or other animals for food, which is useful if you don’t move fast, have no arms to hold things, and your prey can escape in three dimensions. Cone shell venom is easily milked by fooling the snail to sting something else, like a swab…

things that have many small stingers, like jellyfish, are also hard to collect from. One way is to put the jelly (or anemone, which are vaguely related) into a small volume of water, and repeatedly stimulate it to release the poison (mild electric shock, or just poking with a glass rod, works well). Then you end up with a dilute soup of the poison, which is separated from the water and concentrated by chromatography. Most of these are proteins, and we have very advanced techniques for dealing with proteins.

Some small jelly fish have very potent venom in specialised stinging glands that are very tricky to collect from. A colleague in James Cook Uni in Townsville, Queensland, where these things kill people every year, studies box jelly fish venom by making the cells expel venom into a container once the tentacles are removed from the jelly. I am not exactly sure how he does it, as he perfected the technique after I stopped working in Australia. The world’s most lethal sea creature, able to kill an adult very quickly if enough tentacles hit you, is not much bigger than the first joint of your thumb… I should add that they are unusual jelly fish, as they actively hunt fish, and can swim faster than a person. There are maybe a dozen species world wide that have significant venom (also known as sea wasp, or here in Okinawa, as the sea habu), and they occur in many reef areas in the Pacific. It is likely that only the ones in Australia are lethal.

Jamie Seymour


#1024

So dragonflies, right? Have to do their nymph stage in water. So how the hell is the air at the dry, dry summit of Hemeishan down at Bitan full of adults? Thousands of 'em. No water up there at all.


#1025

Don’t forget that they can fly a fair distance. Dragon flies are attracted by horizontally polarised light (which is what predominates in light that reflects off the surface of water) because, as you point out, they live their larval lives in water. Perhaps the summit of that hill has a lot of shiny rock surfaces and is accidentally attracting a swarm of confused dragonflies.

On the other hand, maybe the hill plays good music, or it’s a great restaurant.


#1026

Why are there river valleys?


#1027

Because of rain?

bit if a vague old question, rousseau… can you elaborate?


#1028

No water? There’s that whole swampy area about 100m from the top, as the dragon-flies.


#1029

[quote=“mr. sausage”]Whilst playing rugby a while ago I got elbowed in the 'nads, fortunatelly it was a glancing blow, but I certainly felt sick afterwards , and as we blokes all know a really good shot in the pills will have you vomiting until you dry heave…My question is in 2 parts…
#1. What possible advantage could nature be giving us by making male humans vomit like that :astonished: after a knock to the nuts.
#2. Do animals vomit if they get a good hit, kick or horn to the pills.

one last question why do some animals have their balls on the outside [us, dogs pigs, bulls etc] and some not ?[horses elephants, birds etc] :ponder:[/quote]
Dr Urodacus, because I dearly love you, allow me to help with this question via Cecil Adams.

straightdope.com/columns/rea … use-nausea


#1030

Cute.

Thanks.


#1031

[quote=“urodacus”]Because of rain?

bit if a vague old question, rousseau… can you elaborate?[/quote]
I mean, why does land dip into a valley where a river is? Which came first: the valley to allow the river to flow there, or did the flowing water carve out the valley?


#1032

water will flow down to anywhere lower than the place it starts, even if the height difference is minimal or essentially nil. If there is enough water flowing for long enough, it will erode its own valley. Land that gets uplifted from the crust being pushed around will soon enough become the starting point for many streams, which then begin the process of carving out a river valley.


#1033

So, how does the Queen sing the national anthem?

“… Send me victorious, happy and glorious, long to reign over you, God save me!” :s


#1034

I’ve yet to get salmonella from eating salmon. Should I pay extra?


#1035

[quote=“Chris”]So, how does the Queen sing the national anthem?

“… Send me victorious, happy and glorious, long to reign over you, God save me!” :s[/quote]
Part B of that question: Why do the English suck at football in every world cup? Did they catch All Black Syndrome? Is it genetic and the Kiwis got it from the Poms?


#1036

[quote=“Chris”]So, how does the Queen sing the national anthem?

“… Send me victorious, happy and glorious, long to reign over you, God save me!” :s[/quote]

She does not sing the Royal Anthem, she just hums the tune because she knows she is a crap singer. Charles and Camilla always beat her at Karaoke.


#1037

Salmonella is not named after the fish, but was coined by the Frenchman J Lignières in 1900, in honour (?) the American pathologist Daniel Elmer Salmon (1850-1914).

http://www.bmj.com/cgi/content/extract/314/7073/0/i


#1038

it’s payback for inventing toilet paper, constitutions, and Pall Mall.


#1039

So, what would you prefer to toilet paper?


#1040