Researchers at the University of British Columbia have described two sea spider species new to science, the first new sea spiders described from the Salish Sea in almost a century. One of them, Callipallene pilosuspedes, has red eyes, spine-covered lower legs, and a three-lipped mouth lined with sensory tendrils.

The second species, Tanystylum kiixin, cannot groom itself well and is often coated in debris and even smaller parasites. Specimens were collected on dives up to about 60 feet (18 meters) deep between September 2023 and August 2024 at sites including Quadra Island, Bamfield, Victoria and Vancouver, UBC Science announced on Sept. 23.

The Salish Sea spans British Columbia's Strait of Georgia and Washington's Puget Sound, and the researchers say scientists cannot track how climate change and human activity affect its small invertebrates without first knowing which species live there.

Two New Species, One Unsettling Mouth

Sea spiders, or pycnogonids, are not true spiders. They are marine arthropods related to spiders, scorpions and horseshoe crabs, and their lineage dates back about 500 million years. They feed with a proboscis, breathe through their skin, and some species have as many as 12 legs.

Callipallene pilosuspedes takes its name from Latin for "hairy feet," a reference to the long, curved spines on its lower legs. Under a microscope, it has a short proboscis with claws to grasp food and a triangular, three-lipped mouth covered in sensory tendrils, which UBC compared to a tiny marine Sarlacc pit. It also uses flexible limbs called ovigers, fitted with comb-like spines, to clean its legs. Only a single specimen of this species was found.

Tanystylum kiixin has smaller, less dexterous ovigers and cannot keep itself clean. Researchers frequently found it covered in grime and tiny parasites, which lead author Cormac Toler-Scott described as an ecosystem nested within an ecosystem. The species closely associates with a hydroid called Plumularia setacea. Its name honors an ancient Indigenous village site near where specimens were first collected. Pronounced "kee-hin," the word comes from the sound of waves crashing at the base of the site.

Sea spiders also have an unusual family life. Females produce eggs in their legs, and males gather the eggs, glue them to their own limbs and carry them as they develop.

Filling a Gap in a Poorly Known Ecosystem

The study, published Aug. 26 in Organisms Diversity & Evolution, is described by its authors as the first comprehensive scientific study of sea spiders in the Salish Sea ecoregion. Alongside the two new species, the team redescribed five known species using scanning electron microscopy and molecular data, generated genetic sequences for several species that had never been sequenced, and produced an identification key for sea spiders in the Salish Sea and along the west coast of Vancouver Island.

Toler-Scott, who did the work for a master's degree in zoology at UBC, said he originally wanted to study how climate change and human disturbance affect sea spiders but found little existing information, largely because so little is known about which species live in the region. To understand those impacts and protect the animals, he said, "we have to be able to identify them."

The work draws on records from both sides of the border. The paper's sources include Washington Department of Ecology monitoring data from Puget Sound and community iNaturalist observations, and the authors thanked a University of Washington researcher for his help.

Limits of a Single-Season Survey

This is a peer-reviewed taxonomic study, which means its main job is to describe and name species, not to measure population trends or threats. It does not show that either species is rare, declining, or at risk. With only one known specimen of Callipallene pilosuspedes, scientists do not yet know how widespread it is.

The fieldwork also covered a single season, and Toler-Scott said he expects more undocumented sea spider diversity in the region. The research was funded by the Natural Sciences and Engineering Research Council of Canada, and the authors declared no relevant conflicts of interest.

Sea spider species worldwide are catalogued in the World Pycnogonida Database, and UBC said the two new species have been registered in a global database, making them available to other researchers.

Divers, Beachgoers and the Salish Sea

Despite the unsettling descriptions, these animals pose no known risk to swimmers or divers. The species described here are tiny, and UBC noted that many shallow-water sea spiders live as parasites on larger organisms. Sea spiders range in size from less than a centimeter to more than 70 centimeters (about 28 inches) across, with the largest found in Antarctic waters, not the Salish Sea.

For divers and tidepoolers from Seattle to Victoria, the discovery is a reminder that even well-visited waters hold undocumented life. Recreational divers can contribute by photographing small invertebrates and sharing sightings on citizen science platforms, which researchers increasingly use to track species ranges.

Anyone collecting marine animals should check local rules first. In British Columbia, the researchers worked under a sampling license from Fisheries and Oceans Canada, and Washington has its own collection rules through the state Department of Fish and Wildlife.

The next steps are more surveys, and the new identification key should make it easier for other scientists to recognize new finds.

The bottom line: two small, strange-looking sea spiders have become the first new species of their kind described from the Salish Sea in nearly 100 years. They are harmless to people, but they highlight how little is known about the invertebrates in a busy coastal ecosystem shared by British Columbia and Washington.

What Readers Want to Know

What did UBC researchers discover?

Two sea spider species new to science, Callipallene pilosuspedes and Tanystylum kiixin, the first new sea spiders described from the Salish Sea in nearly a century.

Where were they found?

On dives up to about 60 feet deep at sites including Quadra Island, Bamfield, Victoria and Vancouver in British Columbia, between September 2023 and August 2024.

Are sea spiders dangerous to people?

No. These species are tiny, and sea spiders are not true spiders. Many shallow-water species live as parasites on larger invertebrates.

What makes the red-eyed species unusual?

Callipallene pilosuspedes has red eyes, spine-covered lower legs and a three-lipped mouth covered in sensory tendrils. It also grooms itself with comb-like limbs.

Why does this matter for the Salish Sea?

Researchers say scientists cannot assess how climate change and human activity affect marine invertebrates without first knowing which species are present.

Could more species be found?

Yes. The lead author said the work covered only one field season and that more undocumented sea spider diversity likely exists in the region.