Chengjiang Fauna Carlo (naraoia) Of The Digestive System And Nutrition Strategy Research

As one kind of extinct primeval arthropods, naraoiids, arising up during the Cambrian Explosion and continuing to the end of the early Paleozoic, have been reported and researched in the Early Cambrian Chengjiang fauna, Middle Cambrian Kaili fauna, Middle Cambrian Burgess Shale biota and other well-preserved biotas. Naraoia were preserved with the structure of soft tissues, especially with the digestive system in the Chengjiang fauna. The study of the naraoiids would contribute great significance for the explication of their niche, life habits, the change of the archicontinents and the ancient ecological environment.Based on the previous research, the digestive system of Naraoiids of Chengjiang Fauna is systematacially studied. By means of observation and study under the microscope, combining with the physiological features, digest modes and nutrition strategies of current biological species, this thesis draws conclusions on intestinal morphological and the results of the SEM analysis as follows:1. The Naraoia of Chengjiang fauna, including Naraoia longicaudata and N. spinosa, have distinct differences in digestive system and nutrition strategy, though both of them have diversity in eating pattern.2. N. longicaudata equips with the "Crop" at the head of the digestive system and has pairs of digestive glands with different functions beside the intestinal canal (foregut and midgut), whose digestive mode prefer extracelluar digestion. While N. spinosa has the complex arborescent branches in the anterior shield and pairs of gut caeca beside the intestinal canal (foregut and midgut), whose digestive mode is mainly based on intracellular digestion.3. Both N. longicaudata and N. spinosa are deposit feeder and may grip prey and break down large food fragments. This proposal is based mainly on the presence of a feeding apparatus (endopods with strong spinose endites), but, in principle, such spines could have other functions, for instance in keeping animals together in mating.4. Both N. longicaudata and N. spinosa are well adapted to the intense competition in the foodless original marine environment. It indicates that the creatures of the marine environment in the early Cambrian have produced certain complementary to adjust in living habits, ways of feeding, digest modes and eating methods. The obvious multifarious strategy of digestion and absorption is getting established. To meet the needs of growth, development and reproduction, they produced certain complementary combing with their own living habits in process of nutrition digestion and absorption.