Tanner Mierow

Animals have to respond to their environment in order to survive. In order to do so, animals have remarkable sensory systems that are able to acquire, process, and respond to environmental stimuli. A group of animals that are exemplary models to study sensory systems are visually guided predators. Visually guided predators have advanced visual systems (eyes and corresponding neurons) that allow them to efficiently track and capture prey items. Visually guided predators commonly use eye movements to track visual stimuli, such as prey items. The two types of eye movements are saccadic and smooth eye movements. In saccadic movements, the animal tracks a visual stimulus in “stop-and-go” movements that allow it to fixate on the stimulus and then catch up with the stimulus movement as it moves. In opposite fashion, smooth eye movements are where the animal continuously tracks the visual stimulus with no breaks in movement. Within invertebrates, not many species have showcased smooth movements with the exception of dragonflies. Since dragonflies can carry out smooth movements, we hypothesized that other highly predaceous insects with well developed visual systems may be able to carry out smooth movements. In order to test this idea, we studied praying mantids (Tenodera sinensis) to investigate how they track a visual stimulus at three different speeds. We discovered that praying mantids do not use smooth movements but instead use saccadic movements of the head and thorax to track visual stimuli. While mantids did not show case smooth eye movements, we found that mantids adjust saccade length, fixation length and frequency depending on the stimulus speed.