Two New Sea Spiders Discovered Off B.C. After a Century

UBC researchers found two new sea spider species off Vancouver and Victoria, the first new sea spiders described in B.C. in nearly 100 years.

UBC researchers have described two previously unknown species of sea spider from the waters off Vancouver and Victoria — the first new sea spider species discovered in British Columbia in nearly 100 years, per CTV News and CHEK News. CHEK News reports the animals were found during dives in 2023 and 2024 off Quadra Island, Bamfield, Victoria and Vancouver, at depths ranging up to 18 metres. One is named Callipallene pilosuspedes; the other, Tanystylum kiixin, is pronounced 'kee-hin' after the ancient Indigenous village site where it was first collected.

A century-long gap in new sea spider descriptions is less a sign the coast is exhausted than that nobody has been looking, according to CHEK News. Lead author Cormac Toler-Scott told CHEK News this is the first study to search the entire region specifically for sea spiders, making it a foundational piece for the group in the area. The discovery is also a reminder of how cryptic these animals are: CHEK News notes most B.C. sea spiders are small and transparent, and many beachgoers would not recognize one at all.

CHEK News describes Callipallene pilosuspedes as red-eyed and hairy-legged, with a short proboscis bearing claws to grab food and a three-lipped mouth covered in sensory tendrils — 'a tiny marine Sarlacc pit,' as Toler-Scott put it. Tanystylum kiixin's egg-carrying limbs are so small and undexterous that it cannot groom itself effectively, and researchers frequently found it covered with tiny protist parasites of its own, which Toler-Scott calls 'an ecosystem within an ecosystem within an ecosystem.' The two new species are about one centimetre long, on the small end of a group that reaches more than 70 centimetres in Antarctica, per CHEK News.

Globally about 1,400 sea spider species are documented, versus roughly 50,000 terrestrial spiders. Toler-Scott told CHEK News that studies like this create a baseline scientists can use to track change over time, particularly as climate change alters coastal waters, and that marine arthropods make up a huge portion of environmental biodiversity.

With 20 sea spider species now documented in B.C. and the first region-wide survey complete, the finding reframes the province's intertidal life: Toler-Scott told CHEK News these are benthic animals that stay on the seafloor rather than swim, so anyone encountering one will most likely see it clinging to something on a dock.