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World Register of Deep-Sea Species

Welcome to the World Register of Deep-Sea Species (WoRDSS), a taxonomic database of deep-sea species based on the World Register of Marine Species (WoRMS). This site was launched in December 2012 as a project of the International Network for Scientific Investigation of Deep-sea Ecosystems (INDEEP).

The primary goal of the project is to build a comprehensive database of known deep-sea species and to present this as a thematic species database (TSD) of WoRMS, with all data dynamically linked to WoRMS and their team of taxonomic editors. A secondary goal is to accumulate high quality specimen images of deep-sea species and to present these on both the website and the iOS app (Deep Sea ID, currently in development) that allows offline-viewing of the complete database and imagery to assist with identifications at sea and in the laboratory. Through WoRDSS, we are also providing taxonomic references (sources) that will allow researchers and educators easier access to identification literature.

The WoRDSS project provides an open-access source of quality taxonomic information and imagery on deep-sea species and at the same time enhances the WoRMS database through the provision of images, new sources and editorship. We welcome contributions and corrections.

What is a deep-sea species?

There is no single definition of 'deep-sea'. Traditional classifications have used the continental shelf break at approximately 200m water depth as the boundary between 'shallow' and 'deep sea' (Gage & Tyler 1991), with further classifications of the deep sea into bathyal (~200-4000m), abyssal (~4000-6000m) and hadal (6000m+). More recent schemes such as the Marine Ecoregions of the World (MEOW) have categorised coastal and shelf areas as extending to 800m depth ( Spalding et al., 2007). The Global Open Oceans and Deep Seabed (GOODS) biogeographic classification highlights the upper bathyal (300-800m) as the shallowest 'deep-sea' region (UNESCO 2009).

The current criteria for inclusion in the WoRDSS database is a sample depth of greater than 500m, including both pelagic and benthic species. If a species has been recorded below 500m, it may be included in the database, even if it ranges shallower than this depth. Hence the database includes many species which have traditionally been viewed as shallow-water species, but have been occasionally recorded from the deep sea. The register, therefore, may include species that are not native in the deep sea habitat, but range into it under certain circumstances.

The 500m criterion has been chosen as it is a depth at which seasonal variation in physical parameters (e.g temperature and salinity (Thistle 2003)) as well as the influence of sunlight becomes minimal. Species recorded below 500m, but are known to range above 500m, are also included as they may contribute significantly to the ecology of the deep ocean ecosystem and are likely to be encountered in deep-sea samples.

The criteria for inclusion in the database will be reviewed periodically and we welcome feedback.

Database sources

All of the taxonomic information presented is sourced from WoRMS. Species are presented in the WoRDSS database if they are tagged with the relevant contextual field 'Deepsea' in WoRMS. All species tagged as deep-sea are also provided with a 'context source' for this information, as in this example. The initial contexts for WoRDSS were created from the Ocean Biodiversity Information System (OBIS). In addition to the OBIS sources, we have since been actively incorporating deep-sea species lists from individual institutions, scientists and projects. Please consider contributing your species lists to this part of the project to help improve the database, credit will be provided in the context source field.

We are continuously sourcing and including high quality specimen images of deep-sea species. We welcome contributions. Images and their associated data are currently being handled by the WoRDSS team. Images are visible in high resolution on the mobile app (in development) and in a lower resolution on the website.

We are also sourcing taxonomic identification guides to deep-sea groups. These can include original descriptions with traditional keys, monographs, reviews and online interactive keys. These are provided as links on the relevant taxon pages. Please consider contributing identification sources.


In addition to the editors, numerous colleagues have kindly provided input and corrections for content in the World Register of Deep-Sea Species, an effort which is gratefully acknowledged here.
Acknowledgements for 2020: Danielle De Jonge.


Usage of data from the World Register of Deep-Sea species in scientific publications should be acknowledged by citing as follows:

  • Glover, A.G.; Higgs, N.; Horton, T. (2024). World Register of Deep-Sea species (WoRDSS). Accessed at https://www.marinespecies.org/deepsea on 2024-07-12. doi:10.14284/352
If the data from the World Register of Deep-Sea species constitute a substantial proportion of the records used in analyses, the chief editor(s) of the database should be contacted. There may be additional data which may prove valuable to such analyses.

Individual pages are individually authored and dated. These can be cited separately: the proper citation is provided at the bottom of each page.
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