Hostname: page-component-848d4c4894-nmvwc Total loading time: 0 Render date: 2024-06-27T03:54:55.307Z Has data issue: false hasContentIssue false

Mechanical properties of coral skeleton: compressive strength and its adaptive significance

Published online by Cambridge University Press:  08 April 2016

John A. Chamberlain Jr.*
Affiliation:
Department of Geology, Brooklyn College of the City University of New York, Brooklyn, N.Y. 11210

Abstract

Measurement of the compressive strength and elastic modulus of the skeletal material of three common Caribbean corals suggests that the mechanical properties of coral skeleton are an important factor in the adaptive repertoire of these animals. The strength (stress at fracture) of the specimens tested is 12–81 meganewtons/meter2, with material from branched colonies being generally stronger than material from massive colonies. These values are lower than the strength of most other carbonate skeletal materials, but higher than that of carbonate engineering materials like concrete and limestone. The comparatively low strength of coral skeleton may be the result of architectural properties produced by the requirements of competing adaptive factors, such as polyp phototropism, or it may reflect the low probability that a colony will be broken, and therefore need to be stronger, before it achieves reproductive parity. The skeleton of the three species tested here is strongest when stress is applied parallel to the growth direction of the polyps. Strength varies inversely with skeletal porosity. Decreasing porosity in highly stressed colonies represents a potentially valuable adaptation for enhancing strength. The adaptive value of porosity modification may explain differences in porosity and strength between highly stressed branched growth forms and more moderately stressed massive growth forms. Boring organisms reduce the strength of coral skeleton by increasing its porosity. Only minor amounts of boring can produce strength reductions of up to 50%. Specialized, stress-minimizing branch arrangements help maximize resistance of coral structures to mechanical degradation in situations where colony size is unusually large or hydraulic energy dangerously high.

Type
Research Article
Copyright
Copyright © The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Literature Cited

Alexander, R. McN. 1968. Animal Mechanics. 422 pp. Univ. of Washington Press, Seattle.Google Scholar
Buddemeir, R. R., Maragos, J. E., and Knutson, P. W. 1974. Radiographic studies of reef coral exoskeletons: rates and patterns of coral growth. J. Exp. Mar. Biol. Ecol. 14:179199.CrossRefGoogle Scholar
Chamberlain, J. A. and Graus, R. R. 1975. Water flow and hydromechanical adaptation of branched reef corals. Bull. Mar. Sci. 25:112125.Google Scholar
Currey, J. D. 1970. The mechanical properties of bone. Clin. Orthopaed. 73:210231.CrossRefGoogle ScholarPubMed
Currey, J. D. 1975. A comparison of the strength of echinoderm spines and mollusc shells. J. Mar. Biol. Ass. U.K. 55:419424.Google Scholar
Currey, J. D. 1977. Mechanical properties of mother of pearl in tension. Proc. R. Soc. London B. 196:443463.Google Scholar
Currey, J. D. and Kohn, A. J. 1976. Fracture in the crossed-lamellar structure of Conus shells. J. Mater. Sci. 11:16151623.Google Scholar
Dodge, R. E., Aller, R. C., and Thomson, J. Jr. 1974. Coral growth related to resuspension of bottom sediments. Nature. 297:574577.Google Scholar
Donath, F. A. 1964. Strength variation and deformation behavior in anisotropic rock. Pp. 381–297. In: Judd, W. R., ed. State of Stress in the Earth's Crust. Elsevier, N.Y.Google Scholar
Donath, F. A. 1970. Some information squeezed out of rock. Am. Sci. 58:5472.Google Scholar
Donath, F. A. and Guven, N. 1971. Data reduction in experimental rock deformation. Contrib. Geol. 10:89116.Google Scholar
Friedman, G. M., Amiel, A. J., and Schneidermann, N. 1970. Submarine cement in modern Red Sea reef rock. Geol. Soc. Am. Abstr. with Program. 2:554555.Google Scholar
Gilmore, M. D. and Hall, B. R. 1976. Life history, growth habits, and constructional roles of Acropora cervicornis in the patch reef environment. J. Sed. Petrol. 46:519522.Google Scholar
Gilmore, Q. A. 1876. Building Stones. 40 pp. Van Nostrand, New York.Google Scholar
Goreau, T. F. 1959a. The ecology of Jamacian coral reefs. I. species composition and zonation. Ecology. 40:6789.CrossRefGoogle Scholar
Goreau, T. F. 1959b. The physiology of skeleton formation in corals. I. A method for measuring the rate of calcium deposition by corals under different conditions. Biol. Bull. 116:5975.Google Scholar
Goreau, T. F. 1963. Calcium carbonate disposition by corraline algae and corals in relation to their roles as reef-builders. N.Y. Acad. Sci. Ann. 109:127167.CrossRefGoogle Scholar
Goreau, T. F. and Hartman, W. D. 1963. Boring sponges as controlling factors in the formation and maintenance of coral reefs. Pp. 2554. In: Sognnaes, R. F., ed. Mechanics of Hard Tissue Destruction. Am. Assoc. Adv. Sci. Pub. 75.Google Scholar
Graus, R. R., Chamberlain, J. A. Jr., and Boker, A. M. 1977. Structural modification of corals in relation to waves and currents. In: Frost, S. H., Weiss, M. P., Saunders, J. B., eds. Reefs and Related Carbonates - Ecology and Sedimentology. Am. Assoc. Petrol. Geol. Stud. in Geol. 4:135153.Google Scholar
Graus, R. R. and Macintyre, I. G. 1976. Light control of growth form-computer simulation. Science, 193:895897.CrossRefGoogle ScholarPubMed
Gvirtzman, G. and Friedman, G. M. 1977. Sequences of progressive diagenesis in reefs. In: Frost, S. H., Weiss, M. P., Saunders, J. B., eds. Reefs and Related Carbonates—Ecology and Sedimentology. Am. Assoc. Petrol. Geol., Stud. in Geol. 4:357380.Google Scholar
Hein, F. J. and Risk, M. J. 1975. Bioerosion of coral heads: inner patch reefs, Florida reef tract. Bull. Mar. Sci. 25:133138.Google Scholar
Hernandez-Avila, M. L., Roberts, H. B., and Rouse, L. J. 1977. Hurricane generated waves and coastal boulder rampart formation. Proc., 3rd Internat. Coral Reef Symp., Miami. 3:7178.Google Scholar
Moore, W.I., Krishnaswami, S., and Bhat, S. G. 1973. Radiometric determinations of coral growth rates. Bull. Mar. Sci. 23:157176.Google Scholar
Perkins, R. D. and Enos, P. 1968. Hurricane Betsy in the Florida-Bahama area—geologic effects and comparison with Hurricane Donna. J. Geol. 76:710717.Google Scholar
Ryskewitch, , 1953. Compression strength of porous sintered alumina and zirconia. J. Am. Ceram. Soc. 36:6568.Google Scholar
Scoffin, R. P. and Garrett, P. 1974. Processes in the formation and preservation of internal structure in Bermudian patch reefs. Proc. 2nd Internat. Coral Reef Symp. 2:439448.Google Scholar
Shinn, E. 1963. Spur and groove formation on the Florida reef tract. J. Sed. Petrol. 33:291303.Google Scholar
Sorauf, J.E. 1972. Skeletal miscrostructure and microarchitecture in scleractinia (coelenterata). Palaeontology. 15:88107.Google Scholar
Stoddart, D. R. 1963. Effects of Hurricane Hattie on the British Honduras reefs and cays, October 30–31, 1961. Atoll Res. Bull. 95:1142.Google Scholar
Stoddart, D. R. 1965. Re-survey of hurricane effects on the British Honduras reefs and cays. Nature. 207:589592.Google Scholar
Stoddart, D. R. 1969. Ecology and morphology of Recent coral reefs. Biol. Rev. 44:433498.Google Scholar
Taylor, J. D. and Layman, M. 1972. Mechanical properties of bivalve shell structures. Palaeontology. 15:7387.Google Scholar
Vaughan, T. W. 1915. The geologic significance of the growth rate of the Florida and Bahama shoal water corals. J. Wash. Acad. Sci. 5:591600.Google Scholar
Vermeer, D. E. 1963. Effects of Hurricane Hattie, 1961, on the cays of British Honduras. Z. Geomorph. 7:332354.Google Scholar
Vosburgh, F. 1977. The response to drag of the reef coral Acropora reticulata. Proc., 3rd Internat. Coral Reef Symp., Miami. 3:447482.Google Scholar
Wainwright, S. A., Biggs, W. D., Currey, J. D., and Gosline, M. J. 1976. Mechanical Design in Organisms. 423 pp. Wiley, New York.Google Scholar