The cDNA and genome of Frizzled1 from was cloned by the RACE technique. The full-length cDNA of -Fzd1 was 2387 bp, containing an open reading frame (ORF) of 1761 bp encoding a poly-peptide with 586 amino acid residues. SMART analysis showed that -Fzd1 shared common features of the Frizzled family, including a putative signal peptide with 23 amino acid residues, the N-terminal extracellular cysteine-rich domain (CRD) with 10 conserved cysteine residues, a transmembrane region composed of seven transmembrane segments, and a C-terminal "tail" with five key phosphorylation sites. The deduced amino acid sequence of -Fzd1 had high homology and may share a common ancestor with that of Frizzled1 in Cnidaria from Nematostella vectensis, and that of Frizzled1, Frizzled2, and Frizzled7 in vertebrates, including Danio rerio, by the multiple sequence alignment and phylogenetic analysis. None of the introns were included in the genome of -Fzd1. Quantitative real-time PCR analysis revealed that the expression of -Fzd1 transcript was detected in all four developmental stages. The mRNA expression level of <0.01) of that in the medusa. Furthermore, the -Fzd1 transcript was revealed in the tentacle and occurrence sites of strobilation in strobila by whole mount -Fzd1 should be involved in the regulation of asexual reproduction and occurrence of strobilation in .