Architectural and Mechanical Properties of the Black Coral Skeleton (Coelenterata: Antipatharia): A Comparison of Two Species

Black coral skeletons are laminated composites, composed primarily of chitin fibrils and non-fibrillar protein. This paper examines mechanical properties of the composite and the architecture of the chitin component. Two species are shown to differ significantly in their tensile strength and fibril...

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Bibliographic Details
Published in:The Biological bulletin (Lancaster) 1992-04, Vol.182 (2), p.195-209
Main Authors: Kim, Kiho, Goldberg, Walter M., Taylor, George T.
Format: Article
Language:English
Subjects:
Anatomy
Antipathes
Aquatic life
Biological and medical sciences
Chitin
Cnidaria
Cnidaria. Ctenaria
Cnidarians
Coelenterata
Coral reef animals
Coral reef fauna
Coral reefs
Coral reefs and islands
Corals
Ecology and Evolution
Electrons
Fundamental and applied biological sciences. Psychology
Growth rings
Hardness
Insect cuticle
Invertebrates
Marine
Marine biology
Materials
Skeleton
Solar fibrils
Youngs modulus
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Summary:Black coral skeletons are laminated composites, composed primarily of chitin fibrils and non-fibrillar protein. This paper examines mechanical properties of the composite and the architecture of the chitin component. Two species are shown to differ significantly in their tensile strength and fibril structure. The skeleton of Antipathes salix, a Caribbean species of commercial value, is stiffer, harder, darker, more dense, and more hydrophobic than Antipathes fiordensis from New Zealand. The chitin fibrils constitute a greater proportion of the skeleton in A. salix, where they are helically wound in an anticlockwise pattern within layer. Adjacent layers of skeleton are arranged with relatively small layer-to-layer fibril biases. There is no evidence of "helicoidal" structure in this skeleton. The fibrils in A. fiordensis are also wound anticlockwise within layer, but with rather large fibril biases between layers, giving the appearance of a meshwork. Large-scale helicoidal patterns with apparent rotations of 180° characterize this material. Skeletal architecture is compared with the cuticle of insects and other arthropods. The skeletons of both species exhibit spines characteristic of the Antipatharia. We suggest that these have a significant reinforcing effect on the strength of the skeleton, contributing to an overdesign for the habitat in which these organisms presently occur.
ISSN:0006-3185
1939-8697
DOI:10.2307/1542113