NEMATOCYSTS IN FOUR SPECIES OF CORALS

ABSTRACT

The types and distribution of homatocysts in four coral species were studied. Of the 20 maj or categories or nematocysts recognized in the phylum enidaria, five types were encountered in these four corals. They were holotrichous isorhizas, atrichous isorhizas, microbasic masti­ gophore, micro basic amastigophore and macrobasic mastigophore. The type of nematocysts and their abundance varied from coral to coral and even within a single species, the relative distribution of a given type of nematocyst varied in different parts of a polyp. It is suggested that the differences im the nematocysts could be us ed in the classification of corals.

Most of the scleractinian corals form been used in the systematics of actinia­ colonies which assume many shapes such rians (Werner, 1965). However, no such as rounded and massive, branching, use of nematocysts has been made in foliaceous and encrusting. In many corals scleractinian corals. The present study the variation in the shape of the corallum provid es some information on the types is largely determined by ecological of nematocysts and their distrib ution in various parts of the body of four species factors and hence it is difficult to diffe­ of corals. This information seems to be rentiate between a growing colony and of value in their . a species because the fin al form of certain types of corals is influ­ Favia pallida, Fallia valenciennesi, Favites abducens and -Goniopora pectinata enced by the environment ( Gareau, were the corals used in this study. These 1963; Goreau and Hartman, 1963; were collected from . the fringing reef.of Yonge, 1968). Specific differences Palk Bay near Mandapam. Tissue in the morphology and distribution of squashes were prepared from the tenta­ nematocysts in the body are additional cles, oral disc and mesenteries. These characters which could be used in iden­ were examined under a microscope and tifyin g some species of corals. Ne mat o ~ different catfgories of nematocysts were cysts have been reported to be of impor­ id entified according to Weill's 'c lassifi­ tance as a taxonomic feature of cora ls cation 'as'gi ve n by Hyman (1 940). Length and th ese structures have successfull y and width measurements were made Mahasagar , Vol. 7, Nos. 1 & 2, March-June 1974

TABLE 1

Types of nematocysts and their di stribution in different parts of the body of four species of corals.

Coral species Nematocyst Favia Favites Goniopora category Favia pa/lida valenciennesi abducens pectinata T 00 M T 00 M T 00 M T OD M Hlotrichous isorhizas xx xx Xx xx xx xx xx xx xx Atrichous isorhizas x x xx xx xx Microbasic mastigophore x x xx xx xx Microbasic amastigophore x Macrobasic mastigophore x x x x x x xx xx x xx x xx

xx Occur In abundance. T - Tentacle, 00 - Oral disc, M - Mesenteries x - Occur in few numbers or rare.

of undischarged nematocysts using a corals und er study. Their relative distri­ micrometer eye-piece (these measure­ bution in various parts of the body in ments were taken in Favia pa/lida and the four species is given in Table 1. Goniopora peclinata only). All prepara­ Holotrichous isorhizas were present in tions of nematocyst were taken from Favia pallida, F. valenciennes; and Favites living specimens. Several specimel!s of abducens but W

120 WaJar; Nematocysts iN Jour .pecies oj corals

TABLE 2

Length and width measurements oj nematocysts in two spec/es oj corals

Favia pallida Goniopora pectinata Nematocyst Mean Mean Mean Mean category length width length width (.L (.L (.L (.L

Holotrichous isorhizas 38 18

Atrichous isorhizas 39 15

Microbasic mastigophore 35 9

Macrobasic mastigophore 29 15 40 9

abundance of the,e nematocysts also in the macro basic mastigophores of F. varied from region to region in a pal/ida (1:0.52 and G. pectinato (1 :0.23). given polyp. Macrobasic mastigophores Holotrichs of Chrysaoro quinquecirrha were abundant in the tentacles and in the and verrilli have been reported mesenteries o f G. pectinata but were to differ in their length-width ratio rare in the oral disc. In Favites abducens (Calder, 1972)_ these were abundant in the oral disc and The observed differences in the types tentacles but were few in the mesenteries. of nematocysts and their relative distri­ In F. valenciennes; atrichous isorhizas bution could easily be used in the identi­ were sparse in the tentacles and oral disc fication of those species which are but were totally absent in the mesente­ normally difficult to identify from their ries ; micro basic mastigophores and gross morphology. Nematocysts have amastigophores were few in the tentacles been used previously in the taxonomy and absent from the mesenteries and of (Carlgren, 1945; Cutress, oral disc. 1955). Calder (1972) used them to distinguish almost identical-looking The length and width measureriients scyphistoma stages of scyphozoans from of nematocysts from F. pa/lida and G. the Chesapeake Bay. About 20 major pectinata are given in Table 2 .. A com­ categories of nematocysts have been parison of these measurements afe recognized in the Phylum Cnidaria_ difficult to make because of the varied However, only five types have been distribution of nematocysts in the two identified in these four corals. Further, species. However, marked differences in their relative occurrences are not the length-width ratio could be noticed constant in the di Iferent parts of the

121 Mahasagar , Vol. 7, No s. 1 & 2, March -Jlllle 1974 body of the same polyp. Calder (l972) as additional taxonomic characters in observed vari ations in the abund1n:e the identification of corals, but further of nematocysts fr om region to region . ex tensive study is need<.d before esta­ in Rhopi!ema verrilli. The presence of blishing them as valid characters for a particular type o f nematocyst is not the identification of corals whose shapes common in all the spec ies studied. are influenced by environment. Sub­ Favia pallida , F. valenciennesi and divisions of a given nematocyst category Favites abducens can be diffelentiated based on morphoiogical characters from G. peclinala by the absence of (Calder, 1971; Spangenberg, 1964) and holotrichous isorhiz", and by tbe abun­ staining characteristics ( Sutton and dance of atrichous isorhizas and micro­ Burnett, 1969 ) have been made and basic mastigophore in the_ l a tt~r. these may prove to be \aluable for Though Favia pal/ida and F. valenciennesi coral ~axo nomy . have holotrichous isorhizas in good numbers, the latter can be distinguished ACKNOWLEDGEME!'IT from the former in the rare occurrence My thanks are due to Dr. s. Z. of atrichous isorhizas, microbasic mast i­ Qasim, Director, National Institute of gophore and microbasic amastigophore. Oceanography, Goa for his suggestions The relative abundance of these types and encouragement. The award of a also vary in different parts of the body Senior Research Scholarship from the and this feature can also be used for Ministry of Education and Social the identification of a particular species. Welfare, Government of India is grate­ From the results obtained in this study , fully acknowledged. it seems possible to use nematocysts

Regional Cefllre of eM FR I. M. V. M. WAFAR * Mandapam Camp, Tamil Nadu.

* Present address: Nationallnstitute of Oceanography, Dona Paula, Goa.

REFERENCES

Calder, D. R. 1971 Nematocyst, of polyps of Aur"ia, Chrysaora and Cyanea, and their utility in identification. Trans. Am. microsc. Soc. , 90: 269-274. Calder, D . R. 1972 Nematocysts of the medusa stage of Rhopilema verrilli (:Rhizostomeae) [bid., 91: 213- 21 6. Carlgren, O. 1945 Further contributions to the knowledge of the Cnidom in the Anthozoa, especially in tbe Actiniaria. Lunds. Univ . Arsskrifl N. F. 41(9}: 1-24. Cutrcss, C. E. 1955 An interpretation of the structure and distribution of Cnidae in Anthozoa. Sy.l. Zool., 4(3): 120- 137.

122 WaJar: Nema/ocys/s in Jour species oj coarls

Goreau, T. F. 1963 Calcium carbonate deposition by coralline algae and corals in relation to their roles as reef-builders. Ann. N. Y. Acad. Sci., 109: 127- 167. Goreau, T. F . and W. D. Hartman. 1963 Boring sponges as controlling factors in the formation and maintenance of coral reefs. ·In: Mechanisms of hard tissue des/ruction , pp 25-54. Publication No. 75, Am. Ass. Adv. Science , washington, D. C. Hyman, L. 1940 " The Inver/ebrates" . Vol. I. McGraw-Hili, New York. Spangenberg, D. B. 1964 Newobservations on Aurelia. Trans . Amer. microsc. Soc., 83 : 443- 455 . Sulton, 1. S. and J. W. Burnelt. 1969 A light and electron microscopic study of nematocysts of Chrysaora quinquecirrha. J. U1tras/r. Res., 28: 214- 234. Werner, B. 1965 Die nesselkap;e der Cnidaria, mit besonder berucksichtigung dcr Hydroida. I. KlaS5i fi kation und Bedeutung fiir systematik und evolution. Helgol. Wiss . Meeresunt.rs ., 12: 1-39. Yonge, C. M. 1968 Living corali. Proc. Roy. Soc. , 169B.: 329-344.

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