Abstract
The morphology and histology of the planula larva ofEudendrium racemosum (Cavolini) and its metamorphosis into the primary polyp are described from light microscopic observations. The planula hatches as a differentiated gastrula. During the lecithotrophic larval period, large ectodermal mucous cells, embedded between epitheliomuscular cells, secrete a sticky slime. Two granulated cell types occur in the ectoderm that are interpreted as secretory and sensorynervous cells, but might also be representatives of only one cell type with a multiple function. The entoderm consists of yolk-storing gastrodermal cells, digestive gland cells, interstitial cells, cnidoblasts, and premature cnidocytes. The larva starts metamorphosis by affixing its blunt aboral pole to a substratum. While the planula flattens down, the mucous cells penetrate the mesolamella and migrate through the entoderm into the gastral cavity where they are lysed. Subsequently, interstitial cells, cnidoblasts, and premature cnidocytes migrate in the opposite direction, i.e. from entoderm to ectoderm. Then, the polypoid body organization, comprising head (hydranth), stem and foot, all covered by peridermal secretion, becomes recognisable. An oral constriction divides the hypostomal portion of the gastral cavity from the stomachic portion. Within the hypostomal entoderm, cells containing secretory granules differentiate. Following growth and the multiplication of tentacles, the head periderm disappears. A ring of gland cells differentiates at the hydranth's base. The positioning of cnidae in the tentacle ectoderm, penetration of the mouth opening and the multiplication of digestive gland cells enable the polyp to change from lecithotrophic to planktotrophic nutrition.
Article PDF
Similar content being viewed by others
Literature Cited
Allman, G. J., 1871/72. A monograph of the gymnoblastic or tubularian hydroids. Part I: The Hydroida in general. Part II: The genera and species of the Gymnoblastea. Ray Society, London, 450 pp.
Bénard-Boirard, J., 1962. Développement embryonnaire dePodocoryne carnea (Sars) de Roscoff.Podocoryne carnea (Sars) formaexigua (Haeckel). — Cah. Biol. mar.3, 137–156.
Bodo, F. & Bouillon, J., 1968. Étude histologique du développement embryonnaire de quelques hydroméduses de Roscoff:Phialidium hemisphaericum (L.),Obelia sp. Peron & Lesueur,Sarsia eximia (Allman),Podocoryne carnea (Sars),Gonionemus vertens Agassiz. — Cah. Biol. mar.9, 69–104.
Bonner, J. T., 1955. A note concerning the distribution of polysaccharides in the early development of the hydromedusanPhialidium gregarium. — Biol. Bull. mar. biol. Lab., Woods Hole108, 18–20.
Bouillon, J., 1966. Les cellules glandulaires des hydroides et des hydroméduses. Leur structure et la nature de leurs sécrétions. — Cah. Biol. mar.7, 157–205.
Brooks, W. K. & Rittenhouse, S., 1906. OnTurritopsis nutricula (McCrady). — Proc. Boston Soc. nat. Hist.33, 429–460.
Burck, H.-C., 1973. Histologische Technik, Thieme, Stuttgart, 205 pp.
Chayen, J., Bitensky, L. & Butcher, R. G., 1975. Histochemie. Verl. Chemie, Weinheim, 228 pp.
Chia, F.-S. & Bickell, L., 1978. Mechanisms of larval settlement and the induction of settlement and metamorphosis: a review. In: Settlement and metamorphosis of marine invertebrate larvae. Ed. by F.-S. Chia & M. E. Rice. Elsevier, New York, 1–12.
Cowden, R. R., 1965. Cytochemical studies of embryonic development to metamorphosis in the gymnoblastic hydroid.Pennaria tiarella. — Acta Embryol. Morph. exp.8, 221–231.
Hanisch, J., 1966. Spermienentwicklung vonEudendrium racemosum Cavolini. — Naturwissenschaften53, 587–588.
Hanisch, J., 1970. Die Blastostyl- und Spermienentwicklung vonEudendrium racemosum Cavolini. — Zool. Jb. (Anat. Ontogenie Tiere)87, 1–62.
Hargitt, C. W., 1900. A contribution to the natural history and development ofPennaria tiarella McCr. — Am. Nat.34, 387–415.
Harm, K., 1903. Die Entwicklung vonClava squamata. — Z. wiss. Zool.73, 115–165.
Hotchkiss, A. E., Martin, V. J. & Apkarian, R. P., 1984. A scanning electron microscopic surface and cyrofracture study of development in the planulae of the hydrozoan.Pennaria tiarella. —Scanning Electron Microsc.2, 717–727.
Jha, R. K., 1965. The nerve elements in silver-stained preparations ofCordylophora. — Am. Zool.5, 431–438.
Korn, H., 1966. Zur ontogenetischen Differenzierung der Coelenteratengewebe (Polyp-Stadium) unter besonderer Berücksichtigung des Nervensystems. — Z. Morph. Ökol. Tiere57, 1–118.
Kühn, A., 1913. Entwicklungsgeschichte und Verwandtschaftsbeziehungen der Hydrozoen. 1. Die Hydroiden. — Ergebn. Fortschr. Zool.4, 1–284.
Martin, V. J. & Archer, W. E., 1986a. Migration of interstitial cells and their derivatives in a hydrozoan planula. — Devl Biol.116, 486–496.
Martin, V. J. & Archer, W. E., 1986b. A scanning electron microscopic study of embryonic development of a marine hydrozoan. — Biol. Bull. mar. biol. Lab., Woods Hole171, 116–125.
Martin, V. J., Chia, F.-S. & Koss, R., 1983. A fine structural study of metamorphosis of the hydrozoanMitrocomella polydiademata. — J. Morph.176, 261–287.
Martin, V. J. & Thomas, M. B., 1977. A fine-structural study of embryonic and larval development in the gymnoblastic hydroidPennaria tiarella. — Biol. Bull. mar. biol. Lab., Woods Hole153, 198–218.
Martin, V. J. & Thomas, M. B., 1980. Nerve elements in the planula of the hydrozoanPennaria tiarella. — J. Morph.166, 27–36.
Martin, V. J. & Thomas, M. B., 1981a. Elimination of the interstitial cells in the planula larva of the marine hydrozoanPennaria tiarella. — J. exp. Zool.217, 303–323.
Martin, V. J. & Thomas, M. B., 1981b. The origin of the nervous system inPennaria tiarella, as revealed by treatment with colchicine. — Biol. Bull. mar. biol. Lab., Woods Hole160, 303–310.
Mergner, H., 1957. Die Ei- und Embryonalentwicklung vonEudendrium racemosum Cavolini. —Zool. Jb. (Anat. Ontogenie Tiere)76, 63–164.
Mergner, H., 1971. Cnidaria. In: Experimental embryology of marine and freshwater invertebrates. Ed. by G. Reverberi. North-Holland Publ. Amsterdam, 1–84.
Morgenstern, P., 1901. Untersuchungen über die Entwicklung vonCordylophora lacustris Allman. —Z. wiss. Zool.70, 567–591.
Rittenhouse, S., 1910. The embryology ofStomotoca apicata. — J. exp. Zool.9, 333–348.
Romeis, B., 1968. Mikroskopische Technik. Oldenbourg, München, 757 pp.
Summers, R. G. & Haynes, J. F., 1969. The ontogeny of interstitial cells inPennaria tiarella. —J. Morph.129, 81–87.
Thomas, M. B., Freeman, G. & Martin, V. J., 1987. The embryonic origin of neurosensory cells and the role of nerve cells in metamorphosis inPhialidium gregarium (Cnidaria, Hydrozoa). — Int. J. Invertebr. Reprod. Dev.11, 265–287.
Vyver, G. van de, 1964. Etude histologique du développement d'Hydractinia echinata (Flem.). —Cah. Biol. mar.5, 295–310.
Vyver, G. van de, 1967. Etude du développement embryonnaire des hydraires athécates (gymnoblastiques) à gonophores. 1. Formes à planula. — Archs Biol., Paris78, 451–518.
Vyver, G. van de, 1968a. Etude du développement embryonnaire des hydraires athécates (gymnoblastiques) à gonophores. 2. Formes à actinulas. — Archs Biol., Paris79, 327–363.
Vyver, G. van de, 1968b. Etude du développement embryonnaire des hydraires athécates (gymnoblastiques) à gonophores. 3. Discussion et conclusions générales. — Archs Biol., Paris79, 365–379.
Vyver, G. van de & Bouillon, J., 1969. Etude du développement embryonnaire et de l'histogenèse deEleutheria dichotoma (De Quatrefages) (Anthoméduses Eleutheriidae). — Annls Embryol. Morphogen2, 317–327.
Wasserthal, W., 1973. Zur Ei- und Embryonalentwicklung des HydroidpolypenEudendrium armatum. — Helgoländer wiss. Meeresunters25, 93–125.
Wasserthal, L. T. & Wasserthal, W., 1973. Ökologische Bedeutung der Schleimsekretion bei den Planula-Larven der HydroidengattungEudendrium. — Mar. Biol.22, 341–345.
Watson, J. E., 1985. The genusEudendrium (Hydrozoa: Hydroida) from Australia. — Proc. R. Soc. Vic.97, 179–221.
Weiler-Stolt, B., 1960. Über die Bedeutung der interstitiellen Zellen für die Entwicklung und Fortpflanzung mariner Hydroiden. — Wilhelm Roux Arch. EntwMech. Org.152, 398–455.
Weis, V. M. & Buss, L. W., 1987. Ultrastructure of metamorphosis inHydractinia echinata. — Postilla199, 1–20.
Weis, V. M., Keene, D. R. & Buss, L. W., 1985. Biology of hydractinid hydroids. 4. Ultrastructure of the planula ofHydractinia echinata. — Biol. Bull. mar. biol. Lab., Woods Hole168, 403–418.
Wengler, B., 1974. Zur Systematik der HydroidengattungEudendrium Ehrenberg im Mittelmeer. Hausarb. Fachprüf. Lehramt an Gymnasien, Univ. Bochum. 162 pp.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Sommer, C. Post-embryonic larval development and metamorphosis of the hydroidEudendrium racemosum (Cavolini) (Hydrozoa, Cnidaria). Helgolander Meeresunters 44, 425–444 (1990). https://doi.org/10.1007/BF02365478
Issue Date:
DOI: https://doi.org/10.1007/BF02365478