Questions about genetics and crossbreeding

Nitpicky Bastard

Arachnopeon
Joined
Feb 27, 2017
Messages
2
Hey, folks!

So I'm working on a project and I need some help from those who are incredibly knowledgeable about things like spider genetics and mating. The short of it is that I'm starting a YouTube show that picks apart some factual inaccuracies in movies and whatnot and my "pilot" episode covers the movie Arachnophobia, discussing the specifics on why the spiders could never mate. I have a first draft of the script written, but would love another set (or sets) of eyes to pick at it and make sure my research was actually accurate. Anyone that helps will of course be fully credited in the video.

Any takers?
 

AphonopelmaTX

Moderator
Staff member
Joined
May 7, 2004
Messages
1,558
You mean why the real spider used in the movie, Delena cancerides, couldn't mate and produce offspring with an animatronic spider that resembles a mygalomorph? :p
 

Nitpicky Bastard

Arachnopeon
Joined
Feb 27, 2017
Messages
2
I was kind of trying to be quasi-vague and thought hey, I'll just send the script to whoever says they want to help! But instead, that's vague and dumb so what the heck, here's the first draft of the pilot script in its entirety. Have at!
____________________________________________________________________________________________

Hiya folks, Nitpicky Bastard here, picking apart movie inaccuracies because reasons.

In 1990 Amblin Entertainment brought us a sweet love story about an outcast unknown by society, plucked from his home in Venezuela and brought to southern California against his will. While there he finds a mate with which to have many children who in turn go on to rampage and murder the inhabitants of a small town. I am of course talking about Arachnophobia.

[THEME SONG AND INTRO]

Spiders are friggin’ scary. Arachnophobia capitalizes on that fear by taking an unknown species of spider from Venezuela, dropping it into a southern California town, then breeding with a local spider to create hundreds of death babies. What makes the movie particularly unnerving is that it doesn’t dwell on too many fantastic elements and instead leans on the possibility of realism. People will find spiders or other insects travel with them on trips or vacations all the time. Most often those transfers won’t amount to much when they arrive at a climate that can’t support them, but sometimes invasive species will find a niche in the ecosystem and thrive. [INSERT SIMPSONS CLIP OF FROGS IN AUSTRALIA]

With that in mind, the movie takes the bold leap of asking what might happen if an aggressive and poisonous spider is able to find a mate and successfully breed an army of murder children. For the film they used Australia’s Flat Huntsman, sometimes called Avondale spiders, to portray the demonic offspring which are actually pretty much harmless to humans but it does beg the question, is that even possible? Well first, we have to look at a few things.

First, what is this new spider? Being a previously undiscovered species means we don’t know specifically. What we do know is that there are a ton of tarantula species in Venezuela but the only species anywhere near that size is the Goliath Birdeating Tarantula. Given the basic structure of what they start calling The General, it’s pretty clear it’s at least some kind of tarantula. That means that while we may not know the species, we can safely put it under the Theraphosidae family.

Second, and even more importantly, what is the other spider that the General mates with? Well, it’s supposed to be a Southern House Spider, kukulcania hibernalis. We see after the Jenningses first move into their house Molly must take care of a spider found in a box because both Ross and their son Tommy are afraid of spiders. This house spider is moved to the barn at the same time we see The General crawl in through a hole in the wall. This idea is furthered by entomologist James Atherton, played by Julian Sands, says [INSERT CLIP] but that has a series of flaws.

There are obviously plenty of hybrids out there. You can cross a lion and a tiger, a donkey with a horse or a zebra, even an orca with a bottlenose dolphin. But the one thing that all of these have in common is that even if they’re not all from the same Species or even the same Genus, they ARE all from the same family classification. As an entomologist he should know that it’s almost impossible because a house spider isn’t even in the Theraphosidae family like the General should be, it’s the Filistatidae family. That makes their genetic compatibility almost nonexistent.

Another big issue, and pun fully and horribly intended, is the size. When the General is seen doing his creepy spider porn, the female is about a quarter of his size. A female common house spider, or southern house spider in California, has a body that only measures an inch across at the largest. It would be incredibly unlikely for spiders, whose females are traditionally larger, to allow breeding let alone have, um, a spidergina big enough to accept The General’s little general.

It actually would have made much more sense to use a California Brown or Black Tarantula which are fully indigenous to the area. Using that would have fixed the size problem and also gets us closer to genetic compatibility by making them both inside the same family and species. By now we can say that we’ve pretty well proven this isn’t possible but genetics isn’t even the only thing standing in their way.

At this point because the General is an unknown species we have to go back to making a few generalizations. See what I did there? I’m...ashamed of that pun. I really am. Anyway, spider mating rituals can be incredibly precise and contain a lot of very species-specific activities. This could mean courtship patterns or behaviors. Many tarantula species during their respective mating seasons will tap on the entrance to a female’s nest and they’re not even getting to first base unless she comes out of her hole.

But that doesn’t even matter in this case because the southern house spider mating ritual is ridiculously specific. When a male house spider bumps into a female, the male builds a large web around the female while she just sits there with her judgmental eyes boring into him.. When he’s done he pulls on web strands repeatedly to draw the female out of her hole. Then they start a goofy dance where they tap at the other while the male hangs from his web. The whole routine can take well over an hour. [AIN’T NOBODY GOT TIME FOR THAT CLIP]

Speaking of which, the breeding seasons may be distinct. I found no evidence that there is actually a mating season for the common house spider, but Tarantulas in Venezuela tend to mate during the 6-month summer which is the hottest part of the year, or the months of February through August.

So let’s say for a minute that being from different families and species wasn’t an issue, and that, I dunno, the General got this house spider wasted and she forgot all about her inhibitions and need for specific courtship rituals. Even if mating does occur there’s also the high probability that antigenic reactions to the sperm of other species would prevent fertilization anyway. Basically the female spider’s body would see this particular spider spooj as foreign cells that would need to be destroyed.

All of these things combined mean that this chance occurrence in a lonely barn for these two lovers would not let them raise a homicidal family of little baby spiders. They’d have to look into some kind of spider adoption programs. Bad news for the writers of the movie, good news for arachnophobes out there.
 
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