Mantids are top predators in a food chain of other insects and even vertebrates such as small mammals, birds, or reptiles. Using large, compound eyes that are widely spaced for binocular vision, they swivel their heads as far as 180 degrees to spot prey. Most mantids are ambush predators, sitting still and waiting for prey to come close. Their long front legs are armed with rows of sharp spines that they use to grab and impale the prey. A few mantids actively chase prey, running after them on long legs. Once captured, prey are eaten alive, sliced and chewed up piece by piece. Wiggling prey may be eaten head-first . When at rest, mantids fold their long legs beneath them in a prayer-like position, or sit cleaning their legs with their mouths. Sometimes mantids eat each other (cannibalism), such as females that occasionally devour males during mating or hatchlings that cannibalize each other.

An insect has a brain, connected to bundles of nerves (ganglia) in each of its three body segments. Like us, they have sensory nerves that receive information from their environment and send it to the brain. Information comes from many types of touch receptors. Touch-sensitive hairs all over an insect's body are sensitive enough to detect vibrations in the air, such as from an approaching predator. Insect hairs also do chemical detection (chemoreception). Pores at the end of chemoreceptors on mouthparts or other body parts allow odors to reach the nervous system. Insect antennae may have thousands of chemoreceptors, used to detect chemicals in the air (pheromones) emitted by members of the opposite sex. An insect, like us, has a pair of eyes on its head. But, insect eyes are compound, with hundreds or thousands of lenses, together making an image consisting of spots of light, like pixels. An insect's sound receptors are on its legs.