Divers discover two new sea spider species off the Pacific coast
Tiny, hairy-legged, and red-eyed, they creep through the cold waters of the Salish Sea — and until recently, science had no name for them.
Researchers at the University of British Columbia have formally identified two previously unknown sea spider species from this stretch of Pacific coastline. It’s the first new descriptions from the region in nearly 100 years. One grooms itself with comb-like appendages. The other is so consistently coated in parasites that scientists describe it as an ecosystem living on an ecosystem.
A century-long gap in the record
The last time anyone formally described a sea spider species from the Salish Sea, the region’s marine biology was still largely unmapped. Nearly 100 years passed before Cormac Toler-Scott, a master’s student in zoology at UBC, set out to change that — though not by design.
Toler-Scott originally wanted to study how sea spiders respond to climate change and human disturbance. The problem: almost no baseline data existed. “I couldn’t find anything,” he said. Without knowing which species live in the region, tracking how they’re doing is simply impossible.
So Toler-Scott and his team dove to depths of up to 18 meters at sites near Quadra Island, Vancouver, Bamfield, and Victoria between September 2023 and August 2024. They paired close physical observation with genetic analysis — an approach that proved essential for sorting out what they found. The resulting study, published in Organisms Diversity & Evolution, is the most comprehensive look at Salish Sea sea spiders in a generation.
Ancient animals with a very strange body plan
Sea spiders have been around for roughly 500 million years. Related to spiders, scorpions, and horseshoe crabs, they never left the ocean. That ancient lineage shows in their biology — strange even by arthropod standards.
Some species have up to 12 legs. Many feed using a sucking proboscis that extracts fluids directly from host organisms, and they breathe through their skin rather than gills or lungs. When it comes to raising young, it’s the males — not the females — who carry the load.
Reproduction is particularly unusual. Females have ovaries that extend into their limbs, where eggs develop before being released. During mating, the male collects the eggs using specialized appendages near his head called ovigers, coats them in glue secreted from his own legs, and carries the clustered egg sacs on his body until they hatch.
Hairy feet, red eyes, and a mouth like a Sarlacc pit
The first new species was named Callipallene pilosuspedes — Latin for “hairy feet” — after the long, curved spines covering the lower portions of its legs. The legs aren’t its only striking feature, though.
The animal has vivid red eyes and a short, clawed proboscis it uses to grip food before biting. Its mouth is triangular, split into three lips, and ringed with sensory tendrils. Toler-Scott compared the overall effect to a miniature marine Sarlacc pit — the fictional Star Wars creature known for its layered, tentacle-fringed maw.
What makes C. pilosuspedes especially notable is its behavior. Researchers watched it use its ovigers — the same appendages males use to carry eggs — to groom itself. Under a microscope, the sea spider wrapped them around its legs and combed its body clean using spine-like structures, a level of behavioral complexity not previously documented in the region’s sea spiders. Only one specimen has been found so far, making it among the rarest documented invertebrates in the Salish Sea.
An ecosystem living on an ecosystem
The second new species, Tanystylum kiixin, takes its name from an ancient Indigenous village site near where specimens were first collected. Pronounced “kee-hin,” the word evokes the sound of waves crashing at the base of the cliffs — a fitting origin for an animal found in cold, rocky shallows.
Where C. pilosuspedes is a fastidious groomer, T. kiixin is the opposite. Its ovigers are small and inflexible, which appears to severely limit its ability to clean itself. Researchers consistently found these animals coated in dirt, debris, and tiny parasites living directly on their bodies — a condition that led Toler-Scott to describe the species as “an ecosystem within an ecosystem within an ecosystem.” The reduced grooming capacity and the persistent parasite load seem directly connected, a constraint written into the animal’s own anatomy.
DNA unlocks hidden diversity — and hints at more to come
This study is the first to pair detailed imaging with DNA sequencing for sea spiders across the Salish Sea. Several species were genetically analyzed for the first time, and the team produced an identification guide to help future researchers distinguish species throughout the region. Both new species have been registered in a global biodiversity database.
Toler-Scott is clear that this is a beginning, not a conclusion. He completed only one field season and believes additional undiscovered species almost certainly remain. “There’s definitely more diversity out there that we haven’t documented,” he said.
With genetic baselines now established and better identification tools in place, future surveys will have something the last century lacked entirely: a foundation to build on. The Salish Sea’s sea spider diversity is likely far larger than the current record suggests — and researchers are only just starting to look.
You can learn more about this interesting discovery here: Cormac Toler-Scott, Eunji Park, Heather Gordon, Brian S. Leander. Sea spiders of the Salish Sea: Comparative morphology and molecular phylogenetic analysis of seven coastal species (Arthropoda, Pycnogonida). Organisms Diversity, 2026; DOI: 10.1007/s13127-026-00707-3
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