Substratum

In nature, Penaeids spend most of their life in contact with the sea bottom. This is a complex environment with many features that may be of importance to penaeids. Bottom structures such as seagrass play a significant role in defence from predation and in habitat selection. The substratum itself has several properties that may influence penaeids that burrow into it and feed on it: particle size distribution, pore space and porosity, water content, thixotropy and shear strength, as well as organic content and the presence of other organisms. Although there are differences between species, most penaeids prefer sediments with a particle size below 1 mm and above 62 mm. Most penaeids appear to respond to the percentage of mud in the sediment. Several reasons have been advanced to account for this preference. These include the availability of food, the problems associated with respiring when buried, and the ease or difficulty of burrowing in various grades. Habitat selection may also be important for this preference (Dall et al., 1990).