Control of mudcrack patterns by the infaunal bivalve Pseudocyrena

Examination of mudcracks in a supratidal flat on Bahia Honda Key, Florida revealed high concentrations of stationary Pseudocyrena maritima bivalves in mudcracks and few in the mud between cracks. Almost invariably the bivalves were oriented parallel to or coincident with the cracks and were normally present at the intersection points of two or more cracks. These bivalves appear to have strongly influenced the cracking pattern of the mud in which they live, by acting as points of weakness along which parting of the mud preferentially occurred. Preservation of supratidal bivalves in association with ancient mudcracks is unlikely.