How do caddisfly larvae get oxygen while enclosed in a case?

Caddisfly larvae that construct protective cases obtain the oxygen necessary for respiration through a combination of physiological adaptations and behavioral actions.

Physiologically, these larvae possess tracheal gills located on their abdomen or thorax, which allow them to extract oxygen directly from the water. To ensure a constant supply of oxygenated water reaches these gills while they are enclosed within their tubular cases, the larvae perform rhythmic, undulating body movements. These movements actively circulate water through the case, which is typically open at both ends, facilitating efficient gas exchange.123

When the larvae prepare for the pupal stage, they attach their cases to a solid object and seal the ends, leaving only small holes to maintain this essential water circulation.3