Callianassidae Burrows

Statistical trends in the orientation of Thalassinoides isp. burrows were tested at an outcrop of the Glen Rose Formation exposed by Cow House Creek in Coryell County, Texas, USA. Burrow orientations were analyzed using digital land marks, creating vectors characterizing length and orientation relative to North on a horizontal plane. These were plotted as a rose diagram to better visualize any inherent trends and were further analyzed using PAST to provide evidence for preferred orientations via chi-square test. It is hypothesized that these burrows may demonstrate a collective behavior, reflective of traces exhibited by the recent analogs Upogebia pusilla, Upogebia africana, and Jaxea nocturna. Confirmation of these trends and how they relate to their environment would be important to the understanding of thalassinid shrimp ecology and may prove a valuable aid to paleo-oceanographic modeling.

"In vivo observations in laboratory mesocosms and aquaria, accompanied with in situ photographic surveys, have shown that the burrowing shrimp Calocaris templemani has a significant impact on bottom sediment dynamics and geochemistry in the St. Lawrence Estuary. This burrowing shrimp establishes and maintains complex semi-permanent burrows made up of several interconnected, ‘U-shaped’ galleries with generally four or more openings to the sediment surface. In the Estuary, at 345 m depth, Calocaris average density was estimated at 3.4 individuals m−2. Observed individual burrows reached a maximum volume of 0.54 L. C. templemani displaces this volume of mostly anoxic sediments from the subsurface layers (down to 15 cm) to the sediment surface, thereby obscuring some of the natural stratification patterns. With an estimated turnover rate of about 8 L m−2 year−1 of sediment, our calculations suggest that over a period of about 18.75 years, all the sediment to a depth of 15 cm will have been reworked by C. templemani alone.

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