Breeding sac mates.

[salmonpink]

I recently ended up with a 5" male and female ornata that I just recently found out they r sac mates. What's that mean towards breeding. I have been researching a lot on breeding sac mates but not getting clear answers.

 

[captmarga]

I keep hearing that it's not a problem... but are they both the same size? Usually with sac mates the males mature faster and thus can't mate with the females...

I had three P formosas that were sacmate in a communal setup. Both males have matured and are gone. The third was the smallest of the lot is still going strong, and appears to be the female. She's outlived both her brothers. (And molted out since they died, so no eggsacs...)

Marga

 

[salmonpink]

The r both about 5 inches. The female little bigger. Also being sac mates can the be in the same enclosure?

 

[captmarga]

I think many breeders co-hab the pokies at breeding time. They will co-hab, mate, co-hab... then eventually she might eat the male. But that is a risk every time, isn't it? I tried co-habbing my irminia, it lasted for about two weeks, then she ate him overnight. Got a nice sac, but lost a good male.

I know a breeder that has a pair of pokies that have been co-habbing for a couple of months.

Marga

 

[salmonpink]

Yeah. I for sure wanna breed them but sure I will lose my male. I don't want to but i wanna sac lol

 

[grayzone]

Breeding , cohabbing, and getting viable sacks IS possible without getting the male munched. Cohabbing IS risky, but not a death sentence for a male. Leaving him in ENTIRELY TOO LONG can be however.

 

[salmonpink]

Yeah I was not really interested in a communial setup just if it was possible with sac mates but more interested in breeding.

 

[advan]

Poecilotheria ornata is not communal. Use the search function for your original question. It has been covered many times.

Learn how to use it. --------> Clicky It'll be your best friend.

 

[salmonpink]

I did. I got mixed answers. Figured I'd stick with the pro. This site has helped me a lot. I was only curious if sac mates werecominuial. I no that ornatas r not.

 

[Stan Schultz]

I recently ended up with a 5" male and female ornata that I just recently found out they r sac mates. What's that mean towards breeding. I have been researching a lot on breeding sac mates but not getting clear answers.

First, forgive me. I have hijacked entire threads, and become involved in huge flame wars before, for saying this. But, I ardently think it needs repeating.

There's a serious problem with intense inbreeding, and anybody involved in animal husbandry is painfully aware of it. It's even the basis for most places banning human marriages closer than first cousins. Intense inbreeding tends to conserve all mutations, good and bad.

One of my favorite grim jokes is to remark that in a given population of humans there's obviously been far too much inbreeding, and I actually ran into a very practical case of it several decades ago.

I found myself on the island of Sumba in Indonesia, visiting some people in the little farming village of Sumbawa. (I tried finding it with Google Earth, but no joy. But, there are hundreds of unnamed, little villages on the island.) It was the kind of place where even getting to the next village was a major, one or two day undertaking because the roads were little more than two ruts in winding strips of mud between the volcanic rocks.

I was astounded to see that a truly large percentage of people in the village were either cross eyed, or possessed a "lazy eye." After asking a few questions I found out that since WWII the only outsiders to visit the village had been a handful of Catholic priests. (I was quite a sensation because most of the residents had never seen a 6 foot, 200 pound, blue-eyed, blond, white guy before!) Thus, a young Sumbawanese coming of age had very limited choices for mates. And, the rest as they say, is history. Everybody carried the gene. Perhaps 1/4 or more of the residents got a double dose of it. And, I have no idea of what other less obvious traits were also rampant throughout the population.

Without some serious selective breeding, something like that is what we're eventually facing with our tarantulas.

I've had people yell at me, "But, inbreeding, and even incest, are at least common if not the rule in nature! And, wild populations don't suffer from inbreeding." My reply is summed up in the following quote from Natural is Better...:

It is difficult to appreciate the magnitude of mortality rates in nature. Let's consider a generic tarantula: The female matures at age five years and dies at age twenty. Her reproductive career is fifteen years long. During that time she mates with one male per year and produces one eggsac of 200 babies per year. Thus, during her life she produces 15 X 200 = 3,000 babies.

If the population of her species is to remain stable over the long run, she must replace herself and fifteen males, a total of sixteen offspring. All the rest of those 3,000 babies (3000-16 = 2984) must die. The mortality rate is a brutal 2984/3000 X 100 = 99.47%!

In order to survive long enough to reproduce, any baby tarantula -

Must have absolutely no defects.

Must be incredibly lucky!

Thus, in nature, not only are all the defective ones weeded out, but an overwhelming majority of the perfect but unlucky ones as well.

In captive breeding the first reaction is to lovingly save each and every one of the little darlings. (Just as with humans, and with the same effects, see my example above. But, I'll not discuss or mention that topic again in this thread.) And, the end result is that since the late 1980s or early 1990s, since we started breeding tarantulas in numbers, I have noticed a growing number of reports among enthusiasts of developmental defects and an increase in the percentage of deaths of babies in those kinds of tarantulas that breed most often in our cages.

The problem is that we've removed natural selection entirely, and failed to replace it with good selective breeding practices. We breed whatever we're presented with, with little or no attention to family lines or individual traits, good or bad. And, the hobby is going to pay for it dearly in a few decades.

This prompts me to make the following recommendations. (And, this is always what starts the flame wars!)

1) Be very careful of what parents you use. Do everything you can to ensure that they're not closely related. There are times when you might want to violate this rule, but you should do so with great trepidation.

a) If only a few individuals were brought into captivity and bred, intense inbreeding cannot be helped. Lasiodora parahybana and most of the Poecilotheria species fall into this category. For these, the enthusiast must be extremely cautious about which individuals are used as breeders, and culling must be brutal.

b) The enthusiast is trying to establish a captive strain of tarantulas (comparable to a breed of dogs or horses), is trying to fix some desirable characteristic in the captive population, or is trying to breed an undesirable characteristic out of a population. Here again, intensive selective breeding and brutal culling should be practiced.

2) Culling is not a dirty word! It doesn't necessarily mean killing an animal, although that's the expedient and therefore most common method of culling. But, some sort of sorting or culling must be practiced or we're going to end up with the equivalent of that population of cross-eyed Sumbawanese in our tarantulas.

The most practical way, and the one I suggest (And, here comes the slammer!) is to merely leave the siblings from an eggsac together for a few weeks to give them an opportunity to cannibalize their smaller, weaker, slower, deformed, or more stupid brood mates. If you sacrifice even 1/4 of the babies this way, you may lose a little cash if you're a dealer, or your family may disown you if you're an enthusiast just tying to breed some kind of tarantula for the fun of it, but in the long rum you'll be doing the hobby and the tarantulas you love a huge favor.

It's tough love. And, playing God is never simple or easy, and is seldom very satisfying. But, now that you've accepted the job, you need to accept the responsibility!

What you do from here is your choice.


Enjoy your little 7-legged, 9-eyed What-the-!@#$!-is-that?

:biggrin:

 

[Storm76]

The one thing that would interest me in this case, is simply if there are ANY whatsoever scientifally backed up studies regarding "inbreeding with Tarantulas" and that it's causing "bad gene material" and defective T's. Honestly, after all the time the "we know so very little about them", but transferring the results of inbreeding from humans to T's...I don't know, Stan. I'm no biochemist, biologist or anything the like, admittedly and I will say it does sound logical to look upon it the way you wrote there, but haven't T's been inbred for generations already? Are there ANY reports about the offspring of those generations of T's that have been inbred with MORE defects than normal or the like?

Not saying it's not true, I'm merely curious what the -facts- are regarding T's - not humans

 

[advan]

Hmm, Humans vs tarantulas. Should we start separating our feeder colonies too?

With how long you've been in the hobby, I would of thought you would of tried an inbreeding experiment to actually prove your point that inbreeding will develop issues down the road. Although I wouldn't recommend your beloved G. rosea for that project.

Until there is proof, your post is an opinion not fact.

I suggest you also use the search function and find the member that is on his 7th generation of inbred Pterinochilus murinus.

I am not disagreeing that we should try to stay away from inbreeding as much as possible, but how many of the species we have in the hobby today came from but a few WC specimens?

 

[salmonpink]

Wow!! Never looked at it like that.

 

[Thistles]

I work extensively with tropical fish. When I was young, fancy guppies and zebra danios were both staple hobby fish and considered nearly bomb-proof. Conventional wisdom in the fish hobby has also been that breeding siblings together or back to their parents won't really matter. Most of the fancy varieties of fish are from extremely inbred lines. At first there was no effect, but it has been interesting to watch as fish that were formerly considered indestructible have become fairly fragile and also to see the increase in birth defects. A recent shipment of 20 koi had 4 fish that were missing their opercula (gill covers). Almost every shipment of zebra danios comes with several fish with deformed jaws that won't close. Fancy guppies are now one of our most fragile fish and are our 2nd highest loss after platies, another "hardy" hobby staple that comes exclusively in fancy line bred colors.

The freshwater fish hobby is much older than tarantulaculture, and linebreeding has been occurring for much longer. I think that we will start to see the same things in our hobby that fishkeepers have if we continue the same way and follow the same idea that inbreeding only matters in people. Look at fancy dogs and cats! Nothing has more problems than non-working fancy dogs (bulldogs, pugs, chihuahuas...) that are farthest from their original form! Their eyes fall out, they can't breathe, they have skin and allergy issues, their joints are bad... we selected only for looks or a single function and let all these defective animals reproduce!

I also do believe it is happening in tarantulas already. I received a tiny sling as a freebie from a respected breeder. It must have been only 2nd or 3rd instar. It arrived with a very tiny abdomen, but appeared otherwise healthy. Over the next month or so I watched it slowly starve to death. I offered it smooshed crickets, cricket drumsticks and even flightless fruit flies. It pounced on all of the offered food items with gusto, and I'd feel better every time, thinking that it would be nice and fat the next time I saw it. Then, every time, the next morning I would wake to a tiny, skinny sling and a dead prey item rotting on the bottom of his vial. He was able to grab and kill his prey, but not to feed off them. I don't know what the problem was, and I felt terrible when he did finally die, but I honestly don't know what more I could have done. I don't want to be one of those people who blames something (DKS!) other than her own inexperience when one of her charges dies, but really I think there must have been some defect in this particular spider.

Anyway, I guess all my rambling really only means that I think Stan will be proven correct in the long run. Why would we think that something that has been proven to apply to humans and dogs and horses and cats and fish and birds and guinea pigs and... wouldn't apply to tarantulas? Just because we haven't been breeding them long enough to see the ill-effects in force? I think he's 100% correct that we need to cull if we are going to inbreed instead of just posting, "LF MM B. smithi!" taking the first daddy that appears and then coddling every little $piderling. I let my widow sacmates cannibalize ruthlessly, and I plan to practice the same method of culling when I start breeding my Ts.

 

[advan]

The freshwater fish hobby is much older than tarantulaculture, and linebreeding has been occurring for much longer. I think that we will start to see the same things in our hobby that fishkeepers have if we continue the same way and follow the same idea that inbreeding only matters in people. Look at fancy dogs and cats! Nothing has more problems than non-working fancy dogs (bulldogs, pugs, chihuahuas...) that are farthest from their original form! Their eyes fall out, they can't breathe, they have skin and allergy issues, their joints are bad... we selected only for looks or a single function and let all these defective animals reproduce!

Inverts and verts are a whole different ballgame. I will let Jay elaborate on this if he sees it.

I also do believe it is happening in tarantulas already. I received a tiny sling as a freebie from a respected breeder. It must have been only 2nd or 3rd instar. It arrived with a very tiny abdomen, but appeared otherwise healthy. Over the next month or so I watched it slowly starve to death. I offered it smooshed crickets, cricket drumsticks and even flightless fruit flies. It pounced on all of the offered food items with gusto, and I'd feel better every time, thinking that it would be nice and fat the next time I saw it. Then, every time, the next morning I would wake to a tiny, skinny sling and a dead prey item rotting on the bottom of his vial. He was able to grab and kill his prey, but not to feed off them. I don't know what the problem was, and I felt terrible when he did finally die, but I honestly don't know what more I could have done. I don't want to be one of those people who blames something (DKS!) other than her own inexperience when one of her charges dies, but really I think there must have been some defect in this particular spider.

This is a bad assumption. This could go along the lines of us taking away the majority of natural selection, do to us caring for every single spiderling we hatch. Letting some cannibalism to ween out the weaker ones is not a bad idea but it takes a lot longer then just a few weeks. It can take many instars for spiderlings to start really cannibalizing each other. I have seen this with Avicularia, Heterscodra, and Psalmopoeus. The other possibility is your spider was never fed before it was shipped by the breeder. I have seen quite a few from my hatchings molt to 2i, never ate but other wise looked and acted healthy only to eventually perish. That's one reason I don't consider a breeding successful until I have spiderlings that are feeding.

Anyway, I guess all my rambling really only means that I think Stan will be proven correct in the long run. Why would we think that something that has been proven to apply to humans and dogs and horses and cats and fish and birds and guinea pigs and... wouldn't apply to tarantulas? Just because we haven't been breeding them long enough to see the ill-effects in force? I think he's 100% correct that we need to cull if we are going to inbreed instead of just posting, "LF MM B. smithi!" taking the first daddy that appears and then coddling every little $piderling. I let my widow sacmates cannibalize ruthlessly, and I plan to practice the same method of culling when I start breeding my Ts.

If this the way you feel then you are pretty much stuck with WC spiders. Even then there is still a possibility that the other sex you acquire is a relative. Do you know where to get cheap DNA testing?

 

[Thistles]

Inverts and verts are a whole different ballgame. I will let Jay elaborate on this if he sees it.

Of course they are different, but the same genetic principles regarding dominant and recessive genes hold true across kingdoms, let alone phyla. I would be interested in Jay's opinion, though.

This is a bad assumption. This could go along the lines of us taking away the majority of natural selection, do to us caring for every single spiderling we hatch. Letting some cannibalism to ween out the weaker ones is not a bad idea but it takes a lot longer then just a few weeks. It can take many instars for spiderlings to start really cannibalizing each other. I have seen this with Avicularia, Heterscodra, and Psalmopoeus. The other possibility is your spider was never fed before it was shipped by the breeder. I have seen quite a few from my hatchings molt to 2i, never ate but other wise looked and acted healthy only to eventually perish. That's one reason I don't consider a breeding successful until I have spiderlings that are feeding.

Of course it has to do with natural selection. I think Stan's post expanded this discussion to more than a "should I breed sacmates" thread. He stated that what we have done is essentially removed natural selection, but then not stepped in to replace Ma Nature with selective breeding. Inbreeding itself isn't necessarily bad if it is done with exceptional specimens and only occasionally. If there is no way to remove those individuals that are born with an undesirable trait, we will start to see the ill effects. I suppose I should have been clearer and stated that my experience may not have been the result of inbreeding necessarily, but I do think it was the result of eliminating natural selection. That sling didn't have a chance in captivity, much less if it were born in the wild.

If this the way you feel then you are pretty much stuck with WC spiders. Even then there is still a possibility that the other sex you acquire is a relative. Do you know where to get cheap DNA testing?

Nope, you are making my comments way more extreme. I am just advocating culling and breeding for quality, rather than just matching any 2 spiders and saving every little sling. I also make an effort to acquire my spiders from different sources at different ages to minimize the chance that they are full siblings. I haven't bred any Ts yet, but my boyfriend breeds and we are preparing to begin breeding some of mine. When, say, only a dozen or so spiders are originally imported, that is a very narrow gene pool and there is little to be done about the selection of mates. All I'm saying is that we need to replace that with better breeding practices.

 

[advan]

Nope, you are making my comments way more extreme. I am just advocating culling and breeding for quality, rather than just matching any 2 spiders and saving every little sling. I also make an effort to acquire my spiders from different sources at different ages to minimize the chance that they are full siblings. I haven't bred any Ts yet, but my boyfriend breeds and we are preparing to begin breeding some of mine. When, say, only a dozen or so spiders are originally imported, that is a very narrow gene pool and there is little to be done about the selection of mates. All I'm saying is that we need to replace that with better breeding practices.

Here's my question for you. What are these traits that you are looking for? Is it size? Strength? Color? Growth rate? How do you know what spider carries weaker genes then the next? Who is to decide what is an except able adult specimen to breed? This is very far fetched in a hobby were people start off with their first spider and only a few months later are trying to breed it. With a majority of them knowing little at all, much less about Theraphosidae taxonomy. I think we have a much bigger issue with people misidentifying the spiders they are pairing then pairing sac mates. Just my two cents. -Chad

 

[jayefbe]

I'll try to address many things brought up in this thread.

First off, any species in the hobby that are not currently being imported in large numbers, or were originally based on very large numbers of WC stock are already very inbred. I would guess (totally unscientific guess, but there do exist the resources to test it, anyone want to send me a couple grand and DNA samples from a hundred individuals?) that most species in the hobby have an effective population size of less than a hundred. That is so tiny that effects of inbreeding should be quite obvious. With a group of animals in which a few clutches could sustain hobbyist demand, inbreeding is likely to occur on its own. How many G. pulchra clutches are hatched every year in the US? Not many. So how many breeding pairs are inadvertently related?

Line breeding is very different from simple inbreeding. Line breeding consists of selecting for specific traits. Inbreeding does not consist of any deliberate artificial selection. The importance of this is that line breeding will also inadvertently select for alleles that are physically linked (through physical proximity on the chromosome) to the traits under selection. This is important because some of these alleles will also be deleterious. So, line breeding will always increase the frequency of deleterious alleles. Since straight up inbreeding isn't selecting for any specific trait, the increase in deleterious alleles is not as significant. Furthermore, any deleterious alleles will be purged over time, rather than maintained as occurs in artificial selection.

Perhaps most importantly, inbreeding is not always deleterious. There are many plants and animals for which inbreeding is a beneficial trait that has evolved over time (yes, inbreeding is sometimes a good thing for a population). Deleterious effects of inbreeding arise due to the existence of a significant percentage deleterious recessive alleles. Each human carries a handful of deleterious recessive alleles that would be lethal in a homozygous individual. Since we share half of our genome with our siblings, procreating with your sister significantly increases the probability of these genetic defects becoming exposed. However, humans have a high genetic load of deleterious alleles. Not all organisms do. It is possible for a population to purge their genetic load through inbreeding. After a period of time in which there is reduced fitness due to inbreeding, the deleterious alleles are lost due to natural selection, and inbreeding can continue without ill effect.

There are some species of plants that have been inbred (and I'm talking self-fertilized, not sibling fertilized) for thousands of generations. There are other species of plants that won't last two generations of inbreeding without showing decreased seed output or weird defects. It depends on the history of the populations, what type of mating system they use (mostly inbred, mostly outbred, or a little of both) and the natural genetic load that exists. The point is, it's hard to guess how deleterious inbreeding will be without any direct evidence. As humans, we're predisposed to believe that inbreeding is always bad, because it truly has very severe effects when it occurs in our species. But that's not always the case in all sexually reproducing species.

Another point, just because a handful of slings from any clutch won't survive even under optimal conditions isn't necessarily due to inbreeding. It could be caused by developmental issues not associated with genetics, or it could be due to incompatible genetics that naturally occur even in highly outbred pairings. The point is, deleterious inbreeding would result in significant reduction in clutch size and clutch survival, and over a few generations should continually get worse. A single sling is in no way evidence of that. If you have a large percentage of an entire clutch doing that, then something may be going on.

I know a user on here, Garrick I believe?, who inbred OBTs over several generations to see if he could discern any negative effects of inbreeding. He found nothing, and I used to own a handful of his offspring. It's possible that inbreeding will eventually produce issues in our collection. Maybe some species will respond poorly to inbreeding while others won't. Up to now, I haven't seen any evidence that inbreeding has a significant negative effect.

I personally would always outbreed as much as possible, not for fear of deleterious effects of inbreeding, but in an effort to maintain as much genetic diversity as possible. However, if I have a freshly shed MM and the only females are somehow related, I wouldn't hesitate to do the breeding.

 

[Thistles]

Here's my question for you. What are these traits that you are looking for? Is it size? Strength? Color? Growth rate? How do you know what spider carries weaker genes then the next? Who is to decide what is an except able adult specimen to breed? This is very far fetched in a hobby were people start off with their first spider and only a few months later are trying to breed it. With a majority of them knowing little at all, much less about Theraphosidae taxonomy. I think we have a much bigger issue with people misidentifying the spiders they are pairing then pairing sac mates. Just my two cents. -Chad

The "trait" would be fitness. I think you are misunderstanding me. I'm not crusading against inbreeding. I am saying we need to cull better and if possible diversify our gene pool. I do agree that inadvertent hybrids are a big issue, from importers mislabeling to translation errors to simple owner confusion. I had an "A. avicularia" that became an A. metallica. I asked the guy I got it from as a sling and he said he had indeed produced A. metallica at the same time, and it was possible he mixed up my sling. Either way, I won't be breeding that spider.

Jayefbe, thanks for the clear and informative post. My particular sling example was more to point out that breeders should be more vigilant in weeding out weak slings than to say, "this happened because he had an unclefather and a sistermother."

 

[Stan Schultz]

[size=+1]AS I PREDICTED, SO STARTS THE WAR![/SIZE]​

The one thing that would interest me in this case, is simply if there are ANY whatsoever scientifally backed up studies regarding "inbreeding with Tarantulas" and that it's causing "bad gene material" and defective T's. ...

... Are there ANY reports about the offspring of those generations of T's that have been inbred with MORE defects than normal or the like? ...

Rick C. West did so several years ago with a short life span species of African tarantula. It was written up in the British Tarantula Society's publication and is a matter of record. My memory is failing me, but after a very few generations of mating brother to sister (something like 3 to 6) the mortality rate from molting problems approached something like 90%! Perhaps one of the readers of this will have access to that paper. I can't find my copy.

But, we really don't need an extensive, expensive, exceedingly time consuming research base to be absolutely sure it's correct. Geneticists, animal husbandry types, ecologists, even Stone Age goat herders were aware of the basic principle. And, in VIRTUALLY EVERY living organism that proliferates by sexual reproduction (defined as the mixing of genetic material between the parents, not the clandestine tryst in the back seat of your Dad's Chevy!) that has been examined, the fact holds true. If you believe that gravity is universal, so too do you need to believe this one!

... Honestly, after all the time the "we know so very little about them", but transferring the results of inbreeding from humans to T's...I don't know, Stan. I'm no biochemist, biologist or anything the like, admittedly and I will say it does sound logical to look upon it the way you wrote there, but haven't T's been inbred for generations already? ...

While curious little boys and grizzled old flatulences who still thought like curious little boys have probably been keeping tarantulas as pets, at least until their Dads found out, for millenniums, no one ever thought to write a whole book about them until 1958 when Dr. William J. Baerg published his little book, The Tarantula, describing a lot about the biology, lifestyle, and care of tarantulas. (1) So we start counting that year as the beginning of the arachnoculture hobby. I was a freshmen in high school. That's how new our hobby is! About 54 years!

And, no one really bothered breeding tarantulas until after 1985 when the Mexican redknee was listed in Appendix II of the CITES Treaty. Only after we could no longer get the best selling, most popular kind of tarantula in history any more did we begin to try breeding B. smithi. Then, 10 years later, all other Brachypelma were also listed in Appendix II, giving the breeding effort a real kick in the pants.

So, lets say that we've been breeding a few species of tarantulas since 1995. And, let's say that any species of interest had a life cycle of 5 years. (Note that this isn't LIFE SPAN!)

2012 - 1995 = 17 years.

With a 5 year life cycle:

17 ÷ 5 = 3.4 generations in captivity. Fewer than 4 generations! For a relatively fast growing, short life cycle species!

What about B. smithi?

2012 - 1985 = 27 years.

With a 10 year life cycle:

27 ÷ 10 = 2.7 generations in captivity. Fewer than 3 generations!

So, right now we're only beginning to see the beginning of the avalanche, the avant garde.

... Not saying it's not true, I'm merely curious what the -facts- are regarding T's - not humans

This is something that I couldn't mention in TKG for lack of space: While there are a lot of biological characteristics that differ, even contradict each other, between tarantulas and many other organisms, especially vertebrates, there are also a lot of biological characteristics that we share. Those characteristics that were evolved before the great split between our evolutionary lines are generally conserved by both branches. We only differ in those characteristics that were evolved since that fateful day, somewhere between 600 and 650 million years ago, apparently at the end of the Great Snowball earth.

A list of the things we share would include a lot that most enthusiasts wouldn't begin to understand, but here are a few very basic ones that almost everybody should:

1) We're both eukaryotes. That means that we're composed of cells that contain nuclei and other cell organelles. Contrast that with bacteria with bodies composed of a single capsule and filled with a "soup" of biochemicals, but nothing organized above the molecular level.

2) We both reproduce by means of sexual reproduction. That is, our parents both contributed genetic material to produce us. Contrast that with many protozoans and other organisms that only reproduce by budding, dividing, cloning, etc. (Be careful here: There are lots of life forms that have secondarily lost the ability to reproduce sexually, some coelenterates, worms, and insects for instance. These don't count in this discussion.)

3) We both use the Krebs Citric Acid Cycle as the foundation of energy production.

4) We both employ DNA as the mediator of inheritable characteristics..

5) We both follow the basic laws of genetics. (Although there is limited proof of this, all available data confirms this hypothesis, and there is no data to the contrary.)

6) We are both multicellular. That is, we are composed of an integrated, organized mass of cells functioning as a unit.

7) We are both bilaterally symmetrical. (There is some debate about whether this is the result of inheritance from a common progenitor, or a case of parallel evolution because of the radically different embryology evidenced by the two groups.)

8) Our bodies are both organized into specific tissues, organs, and organ systems, each of which has specialized functions.

9) We both engage in "predation." That is we both subsist by eating other things. Contrast that with plants, archeans and many bacteria for instance, which are more or less self sufficient.

And, there are many more. Few or none of these have any direct consequences on tarantulas' care in captivity, so these characters almost always go unmentioned. But, now you know.

So, when you start comparing tarantulas and humans, your first challenge is to distinguish between those characteristics that are exceedingly ancient, and those that are merely "mildly" ancient, i.e., evolved after the big split about 600 million years ago. And, it appears that Darwinian evolution, including natural selection, in some form or other has been at work since the dawn of life on Earth, several billion years before that.

Since we apparently share a common genetic system, and the same selective forces are acting on both we and our tarantulas (at least in nature), that in this case at least, we CAN use humans or at least vertebrates as a working model. And, if you decide not to, the onus is on you to explain why you think there's a difference. And, this argument must withstand the test of time: Whether you're comparing apples to apples because the characteristic predates the great split, or apples to oranges because the characteristic evolved after the great split.

Now, if you want to start talking about waste removal (e.g., defecation, urination), for instance, the exact opposite is true because it seems that almost every major evolutionary line of organism has adopted a different strategy, and we have to be really, REALLY careful about identifying similarities and using one as a model to explain another.

Isn't biology a trip?

And, you thought that keeping such simple, primitive organisms as your little 8-legged buddy was going to be SSOOOooo simple!

:biggrin:

:laugh:

:roflmao:


(1) Copies of the original edition of The Tarantula are still occasionally available on the used book market. And, Fitzgerald publishing reprinted that original edition in 1997, so you can still get copies, if not originals. Perform an Internet search for used book dealers or used booksellers. When you find one, type into their search box Baerg tarantula to see a listing of what they have. BE SURE TO CHECK THE PUBLICATION DATE BEFORE PLACING AN ORDER IF YOU'RE LOOKING FOR AN ORIGINAL COPY!