In this study, Bar-On and his colleagues investigated the structural mechanics of the wandering spider Cupiennius salei, which is mostly found in Central America. Wandering spiders don't build a web to catch their prey; instead, they hunt around on the ground.
The researchers chose C. salei because it's easy to breed this species in large numbers year round in the laboratory. They modeled its fangs structurally in experiments and in simulations.
Unlike other biological injection needles, such as mosquito and bee stingers, the fangs of these spiders are curved. The curvature enables the arachnids to attack from different directions and hold their prey in place as they inject their venom, the researchers found.
The hollow, conical shape of the spiders' fangs gives them nearly optimal stiffness per unit volume - a measure of their resistance to deformation - making them ideally suited for piercing prey.
The fangs are a composite of protein and chitin, a carbohydrate molecule found in the shells of many insects and crustaceans, whose microscopic structure is well suited for its purpose, the results suggest.