A perforated gastrovascular cavity in the symbiotic deep-water coralLeptoseris fragilis: A new strategy to optimize heterotrophic nutrition
- Dietrich Schlichter1
© Biologische Anstalt Helgoland 1991
The organization of the zooxanthellate scleractinian coralLeptoseris fragilis was studied. The architecture of the corallite and the histology of the polyparium were analysed for adaptations that enable efficient capture and retention of suspended particles which would increase energy supply. The data indicate that the gastrovascular system ofL. fragilis is not a blind but a flowthrough system. Water entering the coelenteron through the mouth leaves the body not only through the mouth but also through microscopic pores (≂ 1–2 μm) which are located near the crests of the sclerosepta in the oral epithelia. Irrigation is achieved by flagellar and probably also by muscular activity. This type of filtration enablesL. fragilis, which lacks tentacles, to utilize suspended organic material including bacteria. The supposed suspension feeding in combination with effective photoadaptations (presented in former communications) seems to be the basis for the survival ofL. fragilis in an extreme habitat (between-95 and-145 m) and for its, successful competion with other scleractinian species provided with larger catching surfaces, and with other invertebrates depending on filter feeding.