Daily rhytm of feeding activity of a freshwater crab Dilocarcinus pagei pagei in National Park Río Pilcomayo, Formosa, Argentina

WILLINER V.; COLLINS P.

Puerto Vallarta Mexico

Congreso; The Crustacean Society 2000 Summer Meeting; 2000

Instituto de Ciencias del Mar y Limnología & Instituto de Biología Univ. Nac. Aut. de Mexico

The periodicity of systems has a n influence on the activity of organisms in relation with them. It is a product of endogenous rhythms ans response for a succession of days and nights. This change produces the oscillation of the intensive of biological and physical conditions (temperature, light, moisture, predator, prey). These rhythms can be seen in coloration change, ecdysis and feeding of decapods crustaceans. Dilocarcinus pagei is a freshwater crab, a component of invertebrates community of laguna La Blanca. The highest diversity in feeding items was noted at nighttime. The stock was both, plants and animals elements. During the day there was mainly plants matter. This periodicity of feeding process is expected to be result of either endogenous or external factors. About the first one they could involve energetic and physiological needs. With respect to the other one they may include, the pressure to be risk of injury and prey by visual predators and more diversity of feeding resource.