Final answer:
Tarantulas liquify their prey with venom because they have specialized mouthparts that cannot process solid food, and their venom both immobilizes the prey and starts digestion externally, similar to the siphoning process in some insects. This adaptation is crucial for their survival as carnivorous arachnids.
Step-by-step explanation:
Tarantulas have to liquify their prey with their venom and suck their insides out because, as arachnids, they possess a specialized digestive system that cannot process solid food. Their venom serves a dual purpose: to immobilize the prey and to begin the digestion process externally.
The process through which tarantulas ingest food is somewhat analogous to the siphoning mechanism employed by certain insects such as butterflies and moths. These insects use a proboscis to suck up liquid nutrients, whereas tarantulas use their chelicerae and mouth to siphon the liquified insides of their prey.