She, J.; Jiang, C.; Fan, J.; Qian, P.-Y.; Wu, L.

The phylum Cnidaria, encompassing reef-building corals, sea anemones, hydroids, and jellyfish, includes both ecological keystones of the marine biosphere and indispensable models for reconstructing early animal evolution. However, escalating ocean warming, recurrent mass coral bleaching events, and intensifying jellyfish blooms have underscored the urgent need to dissect the molecular underpinnings of cnidarian thermal tolerance, symbiosis, and environmental adaptation. Progress in cnidarian research is hindered by the lack of centralized, high-quality multi-omics resources. To address this, we present CnidoSite (https://CnidoSite.org), a comprehensive, analysis-ready multi-omics platform dedicated to Cnidaria. Spanning 327 species across 120 families, 23 orders, and 7 classes, it integrates 147 full-annotated genomes, 15,642 bulk transcriptomes, 50 single-cell datasets, 46 proteomes, 723 epigenomes, 1,650 metagenomic samples, and 180,652 phenotype records. Complemented by advanced toolkits for multidimensional functional and comparative analyses, CnidoSite provides extensive functional genomic resources, including genome assemblies, phylogenies, fossil entries, functional annotations, BUSCO assessments, and mitochondrial annotations. Key features include 29 co-expression networks with cross-tissue visualization and single-cell atlases to map developmental trajectories and stress responses. In summary, CnidoSite serves as a centralized platform that bridges cnidarian biology, marine conservation, and evolutionary genomics to investigate coral bleaching, symbiosis breakdown, jellyfish blooms, and the mechanisms driving environmental adaptation.