How does toxic saliva help North American short-tailed shrews catch prey?

North American short-tailed shrews (genus Blarina) utilize toxic saliva to effectively hunt and manage their food supply. Their saliva contains both a neurotoxin and a hemotoxin, which are introduced into the prey's body through the act of chewing.1

This toxicity serves a critical purpose in their survival:

• Immobilization: The primary function of these toxins is to immobilize prey, specifically small vertebrates like mice and various invertebrates.21
• Food Storage: By paralyzing their prey—particularly snails—the shrews are able to store them for later consumption.1

Because these mammals have extremely high metabolic rates and must consume a significant portion of their body weight in food daily to survive, this ability to incapacitate and cache prey is essential for maintaining their constant need for energy.21