Fig. 7. In situ pictures of nesting behaviour in C. mariae and nest oxygenation status. (A1) First steps of nest building. (A2) Production of mucus-like slime. (A3) Two individuals entering in a nest. (A4) Illustration of animal density in a nest during daytime. (B) Water O₂-profile in the nest shown in A1-A4. Asterisks indicate individuals. Scale bars, 1 mm.