A sea creature with up to 12 legs, red eyes, and a habit of sucking prey dry through a straw-like mouth just got two new relatives, and researchers found them hiding in shallow water off Vancouver Island, in water divers have explored for decades.

  • 2 new sea spider species confirmed
  • 1,300+ sea spider species now known worldwide
  • 100+ years since the last new sea spider species turned up in this region
  • 500 million years since sea spiders first evolved

What the divers found

A University of British Columbia team led by master's student Cormac Toler-Scott collected the specimens on dives up to 18 metres deep between September 2023 and August 2024, around Quadra Island, Vancouver Island, Bamfield and Victoria. Both animals measure about a centimetre across and belong to the Salish Sea, the inland waters between Washington State and British Columbia.

The first, Callipallene pilosuspedes — Latin for "hairy feet" — has red eyes, a triangular three-lipped mouth ringed with sensory tendrils, and long curved spines on its lower legs. Researchers found only one specimen. It also turns out to be remarkably tidy.

"They're very clean and not all sea spiders can do this," Toler-Scott told NPR, describing how the animal uses limbs called ovigers, tipped with comb-like spines, to groom algae and dirt off its own body.

The second species, Tanystylum kiixin, is named after an ancient Indigenous village site near where it was collected; the name is pronounced "kee-hin," echoing the sound of waves at the base of the site. Unlike its tidier cousin, this one cannot groom itself and arrived covered in debris — and its own parasites.

An ecosystem within an ecosystem

Sea spiders are arthropods, related to scorpions and horseshoe crabs, that never left the ocean. They breathe through their skin, and males — not females — carry the eggs, gluing them to their own bodies until they hatch. Many, including the two new species, live as parasites on a plant-like colonial animal called a hydroid, piercing it to drink out its cells.

"It's everyone's kind of dream to find new species, but it's pretty uncommon," Toler-Scott said. "It's hard to get funding for this kind of work because you go into it not really knowing what you're going to get."

The discovery, published in the journal Organisms Diversity & Evolution, is the first comprehensive look at Salish Sea sea spiders using both detailed imaging and DNA analysis. Along the way, the University of British Columbia team generated new genetic data for species that had never been sequenced and built an identification guide for the region.

Why a century-old gap mattered

Toler-Scott started the project because he wanted to study how sea spiders respond to climate change and human disturbance, only to discover almost no baseline data existed for the Salish Sea. "In order to understand how marine invertebrates are being impacted... we have to be able to identify them," he said.

That gap is common across marine invertebrates generally, a group that is wildly diverse but chronically understudied compared with fish, mammals and birds. Every new species formally registered closes part of that gap and gives conservationists a clearer picture of what is actually living in threatened coastal waters.

Toler-Scott, who had only one field season to work with, expects more species are still waiting to be found in the same waters. The research was funded by Canada's Natural Sciences and Engineering Research Council, and the team has additional dives planned.

So the next time something skitters across a diver's glove in the Salish Sea, there is a decent chance it still does not have a name — yet.