Cats are similar in anatomy to the other felid species, with a strong flexible body, quick reflexes, sharp teeth and retractable claws adapted to killing small prey. They are predators who are most active at dawn and dusk (crepuscular). Cats can hear sounds too faint or too high in frequency for human ears, such as those made by mice and other small animals. Compared to humans, they see better in the dark (they see in near total darkness) and have a better sense of smell, but poorer color vision. Cats, despite being solitary hunters, are a social species. Cat communication includes the use of vocalizations including meowing, purring, trilling, hissing, growling and grunting as well as cat-specific body language. Cats also communicate by secreting and perceiving pheromones.