Cockroaches are insects, not animals, and have a ventral nerve cord. They also have spiracles and a heart with 13 chambers. But unlike other insects, cockroaches have no thorax or abdomen.
Cockroaches have mosaic vision, which means they have the ability to view multiple images of objects. Their eyes consist of ommatidia, clusters of photoreceptor cells. In addition, their bodies contain spiracles for respiration. They are also known to be gregarious and triangular, instead of oval. The ovarian gland is located in the sixth and seventh abdominal segments.
Although cockroaches do not have mouths, they have an open circulatory system and can survive without a head for up to a week. They can also survive without a source of water, but once dehydrated they will die. Some species even have wings.
Cockroaches prefer warm temperatures, and will move from one place to another to find warmer air. They also have some basic drives, including liking to touch objects on all sides. This behavior is known as thigmotaxis. Cockroaches also like to entwine themselves around objects.
Cockroaches were first discovered 280 million years ago in the Carboniferous era. The most common species in North America are the German cockroach, brown-banded cockroach, and oriental cockroach. They can survive up to a week in dry conditions, which is why they are commonly found in moist environments.