Extracellular Digestion

The role of mesenteric filaments of anemones in extracellular digestion was demonstrated by Nicol (1959) in Calliactis parasitica. Components of the food caused the filaments to release extracellular digestive enzymes. The filaments envelop the prey and thus concentrate the enzymes in a small volume right on the food mass. Digestion occurs at the interface of mesenterial filaments and food. Ishida (1936) believed "slime" aided extracellular digestion, and Krijgsman and Talbot (1953) observed a mucus coating on the ingested prey of Pseud actinia JlagelliJera. They suggested that the coating concentrated extracellular digestive enzymes such as protease and lipase on the food (Shick, 1991).

Another mode of extracellular digestion occurs when the food is snared by the tentacles. Such "pre-oral digestion1' has been described for Cerianthus (Tiffon, 1975) and Meteract is magnifica (Schlichter, 1980). Microvilli on the ectodermal cells may absorb the products of this digestion (Schlicter, 1980) or the digested material may be taken in via pinocytosis (Tiffon and Daireux, 1974). One can imagine that phagocytosis is possible here too,

Ill though large food items typically pass into the mouth and phagocytosis occurs via endodermal cells in the coelenteron. Tt is also possible that bacteria are digested by enzymes on the surface of some anemones. Tiffon (1975) observed strong trypsin produced by the ectoderm on the column of Metridium senile, and postulated that it played a bacteriostatic role. This could serve functions of nutrition as well as defense against pathogenic bacteria.

The COMPLETE guide to Aquariums

The COMPLETE guide to Aquariums

The word aquarium originates from the ancient Latin language, aqua meaning water and the suffix rium meaning place or building. Aquariums are beautiful and look good anywhere! Home aquariums are becoming more and more popular, it is a hobby that many people are flocking too and fish shops are on the rise. Fish are generally easy to keep although do they need quite a bit of attention. Puppies and kittens were the typical pet but now fish are becoming more and more frequent in house holds. In recent years fish shops have noticed a great increase in the rise of people wanting to purchase aquariums and fish, the boom has been great for local shops as the fish industry hasnt been such a great industry before now.

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