Nathan J. Kenny ^1* Felipe Aguilera ^2,3*

• ¹ Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, Otago, New Zealand
• ² Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile, Concepción, VIII Biobío Region, Chile
• ³ Centro de Biotecnologia, Universidad de Concepcion, Concepcion, Chile

Despite their ubiquity and significance, the study of spiralians has lagged behind that of other phyla, parPcularly those containing well-established model organisms. This has led to significant gaps in our understanding of their biology across various levels. Fundamental resources, such as genome sequences, are spare within this clade, and spiralians are under-invesPgated compared to vertebrates and insects. Coupled with the genePc and morphological novelPes common among spiralians, our ability to fully comprehend the origins of their intriguing traits is sPll developing.The mulP-faceted challenges posed by climate change highlight the growing problem of our limited understanding of spiralian biology. Within Spiralia, numerous species play crucial ecological roles and are now experiencing rapid climaPc shi\s. Many of these species rely on finely tuned chemical processes, such as those involved in biomineralizaPon (e.g., shell formaPon), making them parPcularly vulnerable to temperature-related impacts. AddiPonally, issues like ocean acidificaPon have especially severe effects on spiralians -consequences of which we are currently ill-prepared to address.Fortunately, the emergence of third-generaPon sequencing pla_orms, such as Oxford Nanopore and PacBio systems, has transformed our ability to generate genomic data. This technological leap has significantly accelerated data producPon by consorPa like the Earth BioGenome Project (Lewin et al., 2022), but also enabled smaller laboratories to invesPgate their model species of interest. Coupled with the growing accessibility and decreasing cost of transcriptomic sequencing techniques, both in the wet lab and at the computaPonal level, studying the impact of climate change on spiralian organisms had never been easier. This Special Issue highlights several global efforts where laboratories have successfully generated high-quality genomic and transcriptomic datasets to understand the biology of spiralian species. For instance, Daniels et al., (2023), combined PacBio and Oxford Nanopore long-read technologies with Illumina short-read sequencing to create a highly conPguous and well-annotated genomic resource for the coastal gastropod, Kelle$a kelle$i. This species plays a crucial role as a fisheries and ecological resource. The genomic and transcriptomic resources presented here will enable future studies on its distribuPon and response to climaPc pressures.These new tools can also be applied to study individual traits relevant to climate change. Achilleos et al., (2024) invesPgated the molecular mechanisms underlying biomineralizaPon in the bryozoan species, Cellaria immersa. This is a crucial but under-explored feature of many spiralian organisms, which could be directly affected by shi\s in temperature, pH, and ocean chemistry. Such changes could lead to the loss of the three-dimensional structure of benthic ecosystems, with cascading effects on food webs. This is an example of how transcriptomic tools provide rapid insights into the molecular basis of biomineralizaPon in non-model spiralian organisms, potenPally aiding in miPgaPng of climate change impacts.In Zúñiga-Soto et al., (2023), similar transcriptomic tools, combined with histology, were used to invesPgate biomineralizaPon in the oyster Crassostrea gigas under low pH condiPons. This study offers a direct glimpse into the environments organisms will soon face globally and their potenPal responses to these changes. Differences in the mantle secretome and morphology observed under these condiPons suggest that organisms may adapt to low pH, illustraPng how these changes can be studied. However, moving forward, we must recognize that these changes in adaptaPons may be subopPmal, potenPally leading to downstream issues stemming from alteraPons in the biomineralizaPon processes.In addiPon to genomic and transcriptomic tools, the availability of new, comprehensive resources enables the study of gene family evoluPon through comparaPve genomics. Edsinger and Moroz (2024) uPlized diverse resources to invesPgate lineage-specific gene family expansions, focusing on heat-sensing TRPM channels in mollusks. Their findings suggest that local segmental duplicaPons may drive adaptaPon to challenging environments, offering potenPal targets for species management. This work demonstrates how recent advances in sequencing technologies have generated new hypotheses about the mechanisms underlying adaptaPon in spiralians and provided a robust framework for tesPng these hypotheses.Altogether, the latest sequencing technologies are a powerful tool in bridging gaps in our understanding of spiralian biology and the potenPal impacts of climate change. We hope that the "Spiralian Genomics in a Changing World" research topic serves as a springboard for a broader range of invesPgaPons into this fascinaPng clade, offering valuable tools to address some of the most pressing challenges that face our planet.