Tracheae are a network of tiny tubes found in the respiratory systems of insects and some other arthropods. They allow air to flow directly to tissues and organs, facilitating gas exchange without the need for a circulatory system. The tracheae open to the outside through small openings called spiracles, which can be closed to minimize water loss. These tubes are lined with a chitinous material that helps maintain their structure. The tracheal system is highly efficient, enabling insects to thrive in various environments. This adaptation is crucial for their survival, especially in habitats where oxygen levels may vary.