Supporting data for "Genome sequencing of deep-sea hydrothermal vent snails reveals adaptions to extreme environments"

The scaly-foot snail (<i>Chrysomallon squamiferum</i>) is highly adapted to deep-sea hydrothermal vents and drew peoples interest once it was found. However, the limited information on its genome impeded related research and understanding of its adaptation to deep-sea hydrothermal vents. Here, we report the whole-genome sequencing and assembly of the scaly-foot snail and another snail (<i>Gigantopelta aegis</i>), which inhabits similar environments. Using ONT, 10X genomic, and Hi-C technologies, we obtained a chromosome-level genome of <i>C. squamiferum</i> with an N50 size of 20.71 Mb. By constructing a phylogenetic tree, we found that these two deep-sea snails were independent of other snails, and their divergence from each other occurred approximately 66.3 million years ago. Comparative genomic analysis showed that different snails have diverse genome sizes and repeat contents. Deep-sea snails have more DNA transposons and LTRs, but fewer LINEs, than other snails. Gene family analysis revealed that deep-sea snails experienced stronger selective pressures than freshwater snails, and the nervous system, immune system, metabolism, DNA stability, antioxidation and biomineralization-related gene families were significantly expanded in scaly-foot snails. We also found 251 class II histocompatibility antigen H2-Aal, which uniquely exist in the <i>Gigantopelta aegis</i> genome, which is important for investigating the evolution of MHC genes. Our study provides new insights into deep-sea snail genomes and valuable resources for further studies.