Methods for obtaining and handling marine eggs and embryos

Hydroid Gonothyraea loveni found on the straightnose pipefish (Nerophis ophidion) in the Gulf of Gdańsk — symbiosis, parasitism or biofouling?

“…In general, the hydrozoa are very sensitive to environmental conditions and do not thrive well in a laboratory, even in aquaria containing running sea water. When moved to a smaller container, the animals are likely to die very soon unless they are kept below room temperature (Costello et al 1971). There are two ways of G. loveni reproduction: asexual and sexual.…”

“…Asexual reproduction: The gonangia, which are carried in the axils of branches, consist of a central blastostyle surrounded by a long, oval gonotheca. The gonophores, which are degenerated medusae, do not break away from the blastostyle but remain attached by short stalks, protruding from the gonotheca in groups of three or four (Costello et al 1971). Sexual reproduction: The eggs are relatively small, about 102 microns.…”

“…In either type of development, the resulting planula is a solid, oval mass of cells, which soon elongates and becomes ciliated, and develops traces of a coelenteron. At this time, it emerges from the gonophore (Costello et al 1971;Hayward, Ryland 1995).…”

“…Soon after that, the base begins to secrete a perisarc. This is followed by elongation perpendicular to the attachment, and the development of a mouth and tentacles at the free end (Costello et al 1971).…”

“…It particularly refers to the genus Obelia from the family Campanulariidae. The polyps remain solitary but may give off non-ciliated planula-like buds (frustules) which creep along the bottom and develop into hydroids (Costello et al 1971;Slobodov, Marfenin 2005).…”