Study of Morphology and Agar Contents in Some Important Gracilaria Species of Indian Coasts

This study reports the morphological, anatomical and agar content difference among various species of Gracilaria. The cortex was found 1-2 layered in G. edulis and G. eucheumatoides whereas 5-6 layered in G. foliifera and G. crassa. The medulla was 6-8 layered in G. edulis, 10-11 layered in G. foliifera, 14-15 layered in G. eucheumatoides and 8-10 layered in G. crassa. Similarly, distinct variations were observed in the structure of cystocarp of these taxa. The outer pericarp was 6-8 layered in G. verrucosa (attached type), 8-9 in Graciriopsis megaspora, 12-13 layered cells in G. edulis, 9-11 layered in G. foliifera, 12-15 layered in G. eucheumatoides and 11-14 layered in G. crassa. The tubular nutritive filaments were radiating type in G. edulis whereas these were penetrating and radiating type in G. foliifera. In G. crassa, the same was produced from a small swollen short base and in G. verrucosa (attached type) it was long. Further, in G. eucheumatoides and Gracilariopsis megaspore, nutritive filaments were not observed. Among various species of Gracilariales studied in this work, agar from Gracilaria verrucosa (floating type or sterile type) showed highest yield with gel strength 260 gm/cm2 and viscosity 10 milipass. Based on the agar quality,