大多数的毒蛇都没有空心的毒牙。它们的毒液沿着毒牙的外部凹槽流下，同时由于咬到猎物之后被吸收而粘性降低。凯伦·霍普金报道。

Snakes are misunderstood. They’re not slimy. They’re not charmed by music. And the poisonous ones don’t all inject venom into their prey through hollow needlelike fangs. In fact, the fangs of most toxic serpents have external grooves that direct the flow of poison. And the venom’s viscosity is key to getting it where it needs to go. So says a study in the journal Physical Review Letters. [Bruce Young et al., "Tears of Venom: Hydrodynamics of Reptilian Envenomation"]

Okay, some snakes do use the "hollow fang trick" to take care of their prey. Rattlesnakes, for example. But most snakes have solid fangs, which they use to punch holes in their victims’ skin before they let the venom fly—or slide. Those fangs tend to have grooves that help direct the flow. But scientists got to wondering how that approach could be effective. Couldn’t struggling prey simply brush off the poison as it trickles?

Turns out that the venom’s viscosity keeps it nestled in the groove. And when a fang penetrates the victim’s tissue, the groove makes a canal that generates suction. That suction pulls the venom into the wound. But it also makes the venom less viscous, allowing it to move even faster into the prey. Because getting bitten by a snake sucks.

—Karen Hopkin