Metamorphosis of the polyp ofTripedalia cystophora (Cubozoa, Carybdeidae) into the medusa

Abstract

ABSTRACT. Metamorphosis of the polyp of Tripedalia cystophora (Cubozoa, Carybdeidae) into the medusa. The life cycle of the Cubozoa is unique due to the complete metamorphosis of the sessile solitary polyp into one single medusa which starts a pelagic way of life. Contrary to the other metagenetic classes of Scyphozoa and Hydrozoa, the cubozoan polyp terminates its polypoid existence definitely when it metamorphosizes. Generally, the metamorphosis of the cubopolyp is characterized by the transformation of its simple, sac-like multiradial body into the tetraradial structures of the much more complicated medusa. The macroscopic phases of the metamorphosis of Tripedalia cystophora Conant are reviewed, and the internal developmental processes which effect and underlie the transformation are described in detail from new histological investigations. Only the oral pole of the polyp is involved in the active processes of transformation whereas the basal pole follows in a more passive way. The most important process is the invagination of a quadrangular furrow around the hypostome of the polyp by which (a) the subumbrellar room {bell cavity) of the developing medusa is formed, and (b) the four gastric pockets within the wall of the bell are folded off from the polyp's simple stomach. The description of the metamorphosis on the whole and the detailed comparison of the principal developmental processes provide evidence that medusa formation of Cubozoa is different from that of the other metagenetic classes of Scyphozoa and Hydrozoa. The systematic and evolutionary consequences as well as general aspects of medusa formation in the phylum Cnidaria are discussed in detail. In conclusion, the pelagic medusa generation has been "invented" by the ancestors of the recent metagenetic cnidarian classes three times independently. EINLEITUNG

Development and polyp formation of the giant box jellyfish Morbakka virulenta (Kishinouye, 1910) (Cnidaria: Cubozoa) collected from the Seto Inland Sea, western Japan

“…However, a complete life cycle has been described only for Tripedalia cystophora Conant, 1897 (Werner et al 1971, Werner 1973a, 1975, 1976a, 1983, Laska-Mehnert 1985, although parts of the life cycles are known for Carybdea brevipedalia (Kishinouye, 1891) (Okada 1927, as Carybdea rastoni Haacke, 1886, Carybdea marsupialis Linnaeus, 1758 (Studebaker 1972, Cutress & Studebaker 1973, Stangl et al 2002, Straehler-Pohl & Jarms 2005, Alatina alata (Reynaud, 1830) (Arneson & Cutress 1976, as Carybdea alata Reynaud, 1830, Chironex fleckeri Southcott, 1956 (Yamaguchi & Hartwick 1980, Hartwick 1991a, Copula sivickisi (Stiasny, 1926) (Hartwick 1991b, Lewis & Long 2005, Lewis et al 2008, as Carybdea sivickisi Stiasny, 1926, and Carybdea morandinii Straehler-Pohl & Jarms, 2011(Straehler-Pohl & Jarms 2011.…”

Seasonality in Polyps of a Tropical Cubozoan: A latina nr mordens

“…Life-cycle studies on cubozoa indicate that unlike scyphozoa, cubozoa do not undergo strobilation; instead the entire polyp undergoes metamorphosis into a medusa [7,8,11,13–16], with exception noted in Carybdea marsupialis from Puerto Rico [17]. During the polyp stage, feeding and asexual reproduction occurs and continues until external factors, or cues, such as temperature [14,15,18–20] or light conditions [16], induce metamorphosis from a polyp to a medusa [1,2,21]. The medusae then grow to sexual maturity and may form predictable spawning aggregations [22].…”

Cytological changes during the metamorphosis from the cubopolypTripedalia cystophora (Cubozoa, Carybdeidae) to a medusa

“…Bei letzterer ist der Polyp sehr viel kleiner als die rasch wachsende Medusenanlage. Er iiberlebt den Knospungsvorgang nut dann, wenn auf den ersten nicht unmittelbar ein zweiter folgt; sonst wird das Polypenmaterial vollst~in-dig aufgebraucht (Reisinger, 1957), wie dies bei Coryne loveni und Eutima cirrhffera (Werner, 1983) oder bei der Prim~rmedusenbildung von Rathkea octopunctata (Werner, 1958;Bouillon & Werner, 1965) immer der Fall ist. Diese Formen der Medusenknospung entsprechen prinzipiell der Metamorphose yon Tripedalia cystophora.…”

“…Bei den solit~iren Cubopolypen begrenzt eine Totalumwandlung jedoch die M6glichkeit, sich durch Polypenknospung weiter zu verbreiten (Werner, 1983). Somit haben Cubopolypen nut eine begrenzte Lebensdauer.…”

“…Die ~iuBerlich erkennbaren Vorg~inge der Metamorphose und die inneren anatomischen Ver~inderungen wurden bereits von Werner (1975Werner ( , 1983 beschrieben. Die vorliegende Arbeit untersucht die tiefgreifenden cytologischen Ver~inderungen wfihrend der Metamorphose, wobei ein besonderer Schwerpunkt auf der Morphogenese der bisher nut in ihrem Bau untersuchten Linsenaugen (Conant, 1898;Yamasu & Yoshida, 1976;Laska & Hiindgen, 1982) liegt.…”