THE LIFE CYCLE OF DACTYLOMETRA QUINQUECIRRHA, L. AGASSIZ IN THE CHESAPEAKE BAY

The common jellyfish or sea nettle of the Chesapeake Bay is the large scyphozoan medusa Dactylometra quinquecirrha, L. Agassiz. This species is a coastal form occurring in tropical and temperate seas throughout the world. In the Chesapeake Bay, as in other brackish water areas (Mayer, 1910; Menon, 1930), it is accompanied by a colorless, milky-white medusa which lacks the pigmented areas of Dactylometra. The primary object of this study has been to elucidate the problems presented by the white medusa, which becomes sexually mature in a growth stage having twenty-four marginal tentacles, thus answering the taxonomic description of the genus Chrysaora of Eschscholtz. Certain workers, including Bigelow (1880), have considered the white medusa a member of the genus Chrysaora, on a basis of the sexually mature form, possessing twenty-four marginal tentacles. Mayer (1910) considers this medusa to be a growth stage of Dactylometra quinquecirrha, the so-called " Chrysaora-stage," believing that the premature development of the gonads is the result of the brackish water conditions. More recently Papenfuss (1936) has considered this white medusa to be a variety of D. quinquecirrha and named it chesapeakeii. The literature on the life cycles of these two forms is limited to brief and scattered observations by Mayer (1910), Stiasny (19191921), Papenfuss (1934), and Truitt (1934). For this reason an investigation of the complete life cycles of the red and the white medusae was undertaken. The results obtained from this investigation are presented at this time.