Two hairy-legged sea spider species discovered in Salish Sea

Cormac Toler-Scott was looking for answers about sea spiders in the Salish Sea when he realized no one had bothered to look for them in nearly a century. The UBC zoology student wanted to understand how these creatures were faring under climate change and human pressure, but the scientific record was nearly blank. That absence—the simple fact that researchers couldn't identify what species lived in these waters, let alone how they were changing—became the starting point for his master's research. What he found, published this fall in Organisms Diversity & Evolution, fills a gap that had been waiting to be closed: two entirely new sea spider species, hairy-legged and red-eyed, living in the waters between Vancouver Island and the mainland.

Sea spiders are ancient animals, having evolved roughly 500 million years ago in oceans that looked nothing like ours. They belong to the same family tree as scorpions, spiders, and horseshoe crabs—arthropods that never made the journey to land. What sets them apart is their strangeness. They can have as many as twelve legs. They breathe through their skin. They possess a sucking proboscis, a tube-like mouth apparatus they use to extract nutrients from their prey or, in the case of some shallow-water species, from larger organisms they parasitize. The males, unusually, are the ones who rear the young. Females produce eggs that develop inside their limbs, then release them through a dedicated pore. During mating, males use specialized limbs called ovigers to collect the eggs, coat them in a secretion from their own legs, and carry them in clusters attached to their bodies until they hatch. In the deepest oceans, some sea spiders grow to more than 70 centimeters long. In the Salish Sea, they are small enough to fit in your palm.

Toler-Scott and his team collected specimens between September 2023 and August 2024, diving to depths of 18 meters across multiple sites: Quadra Island, Vancouver, Bamfield, and Victoria. The first new species, Callipallene pilosuspedes, takes its name from the long, curved spines covering its lower legs—a Latin reference to hairy feet. Under magnification, it reveals itself as something between delicate and grotesque: red eyes, a short proboscis lined with claws for grasping food, and a triangular mouth fringed with sensory tendrils. The creature's ovigers, those egg-carrying limbs, are remarkably dexterous. Researchers watched it use them like grooming tools, wrapping them around its own legs and combing through with spine-like structures attached to the appendages. Only one specimen of this species was found.

The second species, Tanystylum kiixin, carries a name drawn from the Kwakwaka'wakw language. The word, pronounced "kee-hin," echoes the sound of waves breaking at the base of an ancient village site near where the first specimens were collected. This species lacks the grooming ability of its cousin. Its egg-carrying limbs are smaller, less flexible, and as a result the animal accumulates debris and dirt across its body. Within that accumulated material, researchers repeatedly found parasites—tiny organisms living on the sea spider itself. Toler-Scott describes the arrangement as "an ecosystem within an ecosystem within an ecosystem," a nested series of dependencies that reveals how little we understand about these creatures' lives.

The research represents the first comprehensive genetic and morphological study of sea spiders in the Salish Sea. The team sequenced DNA from several species that had never been analyzed before and created an identification guide for the region's sea spider fauna. Both new species have been registered in a global database. But Toler-Scott is clear that this work is only a beginning. He had one field season to conduct his research. The waters hold more species waiting to be named, more lives waiting to be understood. As climate change and human activity reshape the Salish Sea, the ability to identify and track these animals—to know what was here, what is here now, and what is disappearing—becomes increasingly urgent. The nightmare fuel, as Toler-Scott wryly notes, is far from exhausted.