2017 marked a decade since the World Register of Marine Species (WoRMS) was established.
In that time, 21,554 marine species new to science have been described and added to the register. The oceans cover over 70% of the surface of our planet, and yet they still include the least explored regions (http://theconversation.com/how-many-undiscovered-creatures-are-there-in-the-ocean-86705).
After 250 years of describing, naming and cataloguing the species we share our planet with, we are still some way off achieving a complete census. However, we now know that at least 242,500 marine species have been described because their names are managed in the World Register of Marine Species (WoRMS) by almost 300 scientists located all over the world.Since the WoRMS was founded in 2007, the number of species on the list has doubled from 120,000 to 242,500. Interestingly, the number of names in the database is actually almost double this figure (477,500), because many names are no longer valid. This can be for a variety of reasons including synonymy (more than one name for the same species), homonymy (more than one species given the same name) and changes to the classification of a species (reflected by a changed combination of species and genus name). The number of new synonyms and homonyms created is likely now far less than in the past due to faster publication and easier access to data. Still, every year around 20,000 unaccepted names are added to WoRMS, each linked to the valid name in the database (Vandepitte et al., 2018).
Every year almost 2,000 marine species new to science are added to the register. This includes species from relatively well-known groups such as fish, almost 1,300 of which were described in the last decade. Yet, it is among the least studied and most diverse animal groups (molluscs & crustaceans) and in the least explored habitats (tropical shallow seas & deep oceans) that most undiscovered creatures likely remain. Just over 6,000 new marine crustaceans and almost 8,000 marine molluscs have been discovered in the past decade.
With the task of gathering the names for all marine species approaching completion, the focus has shifted to improving the consistency and quality of data, while still keeping pace with the addition of the > 2000 new marine species described annually. As part of our 10-year celebration, we redefined the priorities and longer-term aims for the WoRMS database and have shown users how names are input and why they are represented as they are (Horton et al., 2017).
Keeping an up-to-date list of the world’s marine species is not just for interest but also increasingly important for the protection of our oceans. Extinctions from habitat loss and climate change are progressing at alarming rates. Around 20% of marine species are at risk of extinction and we urgently need to document what species are present, and what is happening to them in order to better understand the causes and devolop possible prevention measures. Biodiversity also underpins many features of the environment that humans depend on. Each new species discovered could provide opportunities for advances in medicine or agriculture.
In 2018, to celebrate a decade of WoRMS’ existence, it was decided to compile a list of our top marine species, both for 2017 and for the previous decade in order to highlight the fascinating discoveries of the numerous new marine species being made every year. A list of the ‘Top Ten Species’ described from ALL habitats and taxa has been announced annually since 2008 (http://www.esf.edu/top10/). Although this list often contains one or two marine species, we decided to pay homage to the ‘largest habitat on earth’ by producing our own list of the top marine species. We hope some of our favourites will make it to global list.
How were the species chosen?
All editors of WoRMS were given the opportunity to nominate their favourite marine species from both the last year (2017) and the previous decade (2007-2017). A small committee (including both taxonomists and data managers) was brought together to decide upon the final candidates. The final decisions reflect the immense diversity of animal groups in the marine environment (fish, crustaceans, molluscs, corals, sponges, jellies, worms) and highlight some of the challenges facing the marine environment today (e.g. invasive species, fragile reef ecosystems threatened by climate change, deep-sea environments impacted by resource extraction).
The final candidates also feature particularly astonishing marine creatures, notable for their interest to both science and the public. Each of these marine animals has a story. It may be the among the deepest living or largest fish known, be considered a ‘living fossil’, an invasive species, the most abundant organism in a habitat, or have remained hidden in plain sight, hoodwinking researchers for decades…
Ten astounding marine species of the last decade (2007-2017)
- Deep-sea lyre sponge – Chondrocladia lyra
- Palauan primitive cave eel – Protanguilla palau
- Deep-sea acochlidiacean slug – Bathyhedyle boucheti
- Tree syllid worm – Ramisyllis multicaudata
- Starry sea wanderer jelly – Marivagia stellata
- The Hoff crab – Kiwa tyleri
- Squidworm – Teuthidodrilus samae
- Jesse Ausubel’s ‘terrible claw’ lobster – Dinochelus ausubeli
- The ‘living fossil’ octocoral – Nanipora kamurai
- Scaly-foot snail – Chrysomallon squamiferum
Ten remarkable new marine species from 2017
- The Mariana snailfish – Pseudoliparis swirei
- The Harry Potter ‘hero’ crab – Harryplax severus
- Bob Marley’s intertidal spider – Desis bobmarleyi
- The invasive ‘spiderman’ worm-snail – Thylacodes vandyensis
- The Californian box jelly – Carybdea confusa
- Palau president’s colonial anemone – Antipathozoanthus remengesaui
- The necklace foraminiferan – Aschemonella monilis
- The hoodwinker sunfish – Mola tecta
- The fiery-red dragon amphipod – Epimeria pyrodrakon
- The Solomon Islands pyramidellid snail – Eurathea solomonensis
Contacts:
Tammy Horton: tammy.horton@noc.ac.uk
Leen Vandepitte: leen.vandepitte@vliz.be
secretariat@marinestations.org 
+44 (0) 1752 426493 
