Fiendly posted:

Resources:
Mr. Vile has shared his own expertise with the thread, answering questions and offering interesting spider facts:
Book lungs and stridulation:

quote:

Tarantulas along with other arachnids that can stridulate like solifugae (camel spiders) usually have their stridulatory organs on the chelicerae, the big things at the front that the fangs are mounted on. You can see the whistling spider there rubbing them together to hiss, kind of like rubbing two sandpaper blocks together. Spiders can't vocalise in any way like we do because they don't have vocal cords, and their lungs aren't connected to their mouth at all. Spider lungs are called book lungs and work in a totally different way to ours, being more like adapted gills filled with "pages" for gas exchange, hence the name. They can't inhale or exhale and rely entirely on passive gas exchange through the "pages" of the book lungs, which are connected to the outside through a pore called a spiracle on the spider's underside.



Tarantulas actually shed part of their book lungs when they moult! The four white patches are the parts of the book lungs that were shed along with the old exoskeleton.

Chelicerae and eating:

quote:

They don't just splurt digestive juices all over the prey and wait for the whole thing to melt, but the exact way they manage their food depends on exactly what animal you're looking at, because spider and scorpion mouthparts get weird.

Spiders and scorpions are defined in part by their mouthparts, which are specialised things called chelicerae. More specifically, the taxanomic group above arachnidae is chelicerata, which are defined by having them and is made up of arachnids, horseshoe crabs and possibly sea spiders, which there's some debate about. In most chelicerata, the chelicerae are weird grabby-claw things used to grab prey and either tear bits off or just generally mash and "chew". Solifugids (camel spiders) are one of the few arachnids that use their chelicerae to hunt and outright kill prey, so they have a particularly large and intimidating pair that do a good job of showing off what they're generally about.



Scorpions, meanwhile, use their claws and venomous sting for the actual hunting, so their chelicerae are generally kept tucked away inside the prosoma (the front part of the body). They're surprisingly dextrous!

Scorpions and spiders, along with all other chelicerata, as far as I know, can only ingest liquid food and have specialised "sucking stomachs" for it. Scorpions manage this by using their chelicerae to tear and slice bits of prey off and draw it into a special pre-oral cavity where digestive fluids melt it down into a sort of soup before being sucked into the stomach proper



Spiders are characterised by having uniquely specialised chelicerae. Rather than being little claws, they contain venom ducts and have a hollow fang to inject their venom with. Exactly how the fangs and chelicerae operate is one of the big divisions in spider taxonomy but I'll get into that later on. The actual mouth of a spider is on the underside right behind the chelicerae, and is used either to force digestive enzymes into the prey, or just generally to spread digestive juices over it, depending on the structure of the chelicerae. Spiders like our tarantula friend just tear and mash the prey into a ball called a bolus and "lick" at it until they're got as much of the digested, liquid parts as they can before throwing the rest away. Other spiders will just make a hole, inject enzymes and then drink up the liquid before repeating the process, ending with either a mostly-intact exoskeleton or the skin and bones of an unfortunate small reptile or rodent.

The arachnid method of digesting food externally and only actually ingesting it once it's liquid has some pretty neat benefits, namely that they don't waste energy on indigestible parts of their prey, and having near-immunity to things like digestive parasites and other nasties that us solid eaters have to worry about being in our food.

Social spiders:

quote:

They are, and most spiders will happily cannibalise members of their own species given the chance. There are a few species that will live communally but they're very much the exception rather than the rule. Some of the cobweb spiders (Theridiidae) are most well known for it and can spin gigantic webs that cover entire trees or areas of forest.



The family actually includes the widow spiders, and despite their reputation they have been known to live communally in captivity, although that could be due to other factors.

Aside from them, at least one species of huntsman spider is known to live communally, crammed together into tiny spaces.

As for tarantulas, I know of very few species that will live together. M. balfouri is the only one I know of that will truly live communally, living in a giant "web castle" together and happily sharing their prey.


Poecelitheria species like the spectacular P. metallica below have been known to live in the same enclosure in captivity, but they very much keep to themselves and make separate webs, so I don't think they can be called communal. Even then, there are plenty of people who tried communal setups and ended up with one big fat spider left before long.

Bogleech has created a series of arachnophobe-friendly blog posts with cute drawings instead of pictures of real bugs: Spiderween

The now-defunct Caustic Soda podcast has done numerous episodes on the animals we meet in Deadly Creatures, often with actual scientists as guests:
Web Building Spiders
Hunting Spiders
Scorpions
Wasps and Hornets
Snakes

The podcast Hound Tall did an episode on entomology covering a wide array of topics and personal anecdotes from the guest entomologist's world travels: Buggin Out! - Extreme Entomology and the Amazon (episode begins at 9:50) [NOTE: extremely vulgar]

Arthro-Pod is a podcast hosted by a rotating group of entomologists, so pick any topic on their episode list that seems interesting and you'll learn everything you need to know about it: Arthro-Pod [CW: lots of pictures of real bugs]

Relevant videos:
Tarantula demonstrates the use of urticating hairs
Meet the spidergoats