So, true spiders digest their food externally by injecting the venom.
That is not quite correct. They inject the venom to kill the prey, after that they will inject digestive fluids which will liquify and pre-digest the insides before the spider slurps it up again. But the venom is not essential to the disgestive process.
harvestmen (daddy long legs) are not venomous and lack the mouth-parts necessary for injection, but they’re not true spiders.
Harvestmen can bite (though many are too small to penetrate skin, it’s very rare), so it’s not like they lack the mouth-parts per se, they just don’t have any venom glands that are feeding into the mouth-parts.
Also Opiliones are not just not true spiders, they are not spiders at all (“true spiders” are one of the 3 infraorders of the spider order). Opiliones are their own order.
However “daddy long legs” could also refer to an actual spider (and a true spider at that), Pholcidae. It’s quite the ambigious name (there is even an insect, the crane fly that is also going by that name in some places).
That is not quite correct. They inject the venom to kill the prey, after that they will inject digestive fluids which will liquify and pre-digest the insides before the spider slurps it up again. But the venom is not essential to the disgestive process.
Harvestmen can bite (though many are too small to penetrate skin, it’s very rare), so it’s not like they lack the mouth-parts per se, they just don’t have any venom glands that are feeding into the mouth-parts.
Also Opiliones are not just not true spiders, they are not spiders at all (“true spiders” are one of the 3 infraorders of the spider order). Opiliones are their own order.
However “daddy long legs” could also refer to an actual spider (and a true spider at that), Pholcidae. It’s quite the ambigious name (there is even an insect, the crane fly that is also going by that name in some places).