Vol. 36 No. 1, 1997

Morphological and Mechanical Properties of Two Alcyonaceans, and Sinularia flexibilis and S. capillosa

Ming-Chao Lin and Chang-Feng Dai*

Inst.of Oceanography, National Taiwan Univ.,P. O.Box23-13,Taipei, Taiwan 106

Ming-Chao Lin and Chang-Feng Dai (1997) Drag and changes of colony morphology under various flow velocities of 2 sympatric alcyonaceans, Sinularia flexibilis and S. capillosa, were studied. The mechanical properties of tissues from these 2 species were also investigated.  Colonies of the 2 species have similar mophological and  mechanical properties. Flexibility of the colonies enables them to bend intoa drag-reducing or ientation at higher flow velocities by collapsing the colony, thus bringing it nearer the substratum. In addition, the 2 species also have a similar volume fraction of sclerites and similar stiffnessof intact colony tissue.  However, the  2 species differ in sclerite size, and the stiffness of S. flexibilis after decalcification is higher than that of S. capillosa. These facts indicate that sclerites may not be the only factor affecting the stiffness of S. flexibilis and S. capillosa; the  stiffness of the mesoglea may also play an important role. The results show that these 2 sympatric species possess similar morphological and mech-anical  properties to reduce drag, but they achieve this through different skeletal constitutions.

Key words: Biomechanics, Drag, Sclerite, Water flow.

*Correspondence: E-mail: corallab@ccms.ntu.edu.tw