Khabibulina V.R.1, Starunov V.V.2 2020. FMRFamide immunoreactive nervous system in the adult Cassiopeia xamachana scyphopolyp and at the early stages of planuloid formation // Invertebrate Zoology. Vol.17. No.4: 371–384 [in English].

1 Department of Invertebrate Zoology, Saint Petersburg State University. Universitetskaya nab. 7/9, 199034 Saint Petersburg, Russia. E-mail:

2 Zoological Institute of the Russian Academy of Sciences, Universitetskaya nab. 1, 199034 Saint Petersburg, Russia. E-mail:

doi: 10.15298/invertzool.17.4.03

ABSTRACT: Studies on the cnidarian nervous system are usually dedicated to model objects such as Hydra and Nematostella vectensis polyps or jellyfish of a few other species, whereas data about other groups and life cycle stages are fragmentary. This study is focused on the nervous system morphology of the mature Cassiopeia xamachana scyphopolyps and during the planuloid formation. We revealed two main groups of the FMRFamide-immunoreactive nerve elements in scyphopolyps. The neurites of the first group accompany musculature in the body column, tentacles and hypostome. Neurites of the second group form a weakly concentrated nerve ring at the margin of the oral disk, which may represent integrative center of the animal. During the planuloid formation no FMRFamide-immunoreactive nerve elements from the mother polyp contribute to the growing bud. This suggests that the FMRFamide-like component of the nervous system in the planuloid develops independently after separation.

KEY WORDS: cnidaria, nervous system, scyphozoa, Cassiopeidae, musculature, budding.

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