The Burrows of Callianassa tyrrhena (Petagna 1792) (Decapoda: Thalassinidea)

Burrows of the thalassinidean shrimp Callianassa tyrrhena were investigated by in situ resin casting on two tidal flats in the Adriatic Sea. The burrow openings are characterised on the surface by simple holes or funnels. The number of openings per burrow ranges from 2 to 4. Burrows consist of a single or multiple shallow U with thin shafts (2 – 11 mm diameter) leading to the surface and a main central spiral shaft consisting of a series of enlarged chambers (with an elliptical cross‐section of up to 10 × 20 mm) linked by other segments (with a circular cross‐section of 5 to 13 mm in diameter). Several chambers filled with seagrass debris branch off. Burrows reach a depth of down to 62 cm and have a volume of up to 300 cm3. Additional information is provided on the redox properties of the burrow wall, and on bacterial numbers and biomass along the burrow wall and in the debris chambers. The morphology of the burrows and the impact of the imported organic matter on the deeper sediment layers is discussed.