Morphology and molecular assessment of a Jellyfish species (Cnidaria: Scyphozoa) Pelagia noctiluca with potential to form bloom in Southeast coast of Iran (Oman Sea)

In recent years، plankton Bloom has increased in coastal waters around the world. Class of Scyphozoa belong to phylum Cnidaria has known as true jellyfish and most of these zooplankton plankton in coastal waters have potential to form bloom that can have adverse effects on fishing and fish stocks، Thus، their identification is essentials. In the present study، a Jellyfish species that formed bloom in February 2012 in Chabahar Bay had been sampled. The samples were morphologically identified، then it’s DNA extracted، PCR and sequencing of the 18S-rRNA gene was done. The sequence of Iranian species with 25 other sequences from the gene bank in the same gene region was compared. Phylogenetic analysis using Maximum likelihood (ML) was performed. The blast result showed 18S rDNA sequence of our species with 99% identity with Pelagia noctiluca. According to the results of morphological and molecular analysis the sample was identified as P. noctiluca. In the phylogenetic tree Iranian species is in the Pelagiidea family clade and supported with 98% bootstrap. The overall results showed that the Semaeostomeae is a paraphyletic group. The results also revealed that molecular and morphological analysis could help to identify jellyfish species. This is because most of jellyfish species’ body is made of water and their morphological identification is difficult.