A team of researchers in Canada has described two previously unknown species of sea spider, adding to a family of marine arthropods that scientists have only begun to map in detail. The animals turned up in shallow water in the Salish Sea, the body of water between Washington State and the Canadian province of British Columbia, and the researchers say they are the first sea spiders recorded from that area in more than a century.
The finds came out of fieldwork conducted between September 2023 and August 2024, when the team collected specimens from the waters off the islands of Vancouver and Quadra in British Columbia. Both new species measure only about a centimeter across — a reminder that some of the ocean's most unfamiliar animals are also among its smallest. The specimens were recovered by researchers at the University of British Columbia, the institution that led the discovery.
Sea spiders are marine arthropods belonging to a class called Pycnogonida, and they are not the same thing as the spiders people picture crawling around a house. Scientists have identified more than 1,300 species in the class so far, and the new pair described from the Salish Sea extend that growing list. Their name is misleading in a useful way: the creatures look spider-like, with eight legs, and they are close relatives of terrestrial spiders, but their resemblance masks a very different way of life.
Cormac Toler-Scott, the lead researcher on the team, told NPR that the animals' connection to their land-based relatives is real but incomplete. Sea spiders never made the transition onto land, he said, and they depend on water to survive. They move slowly, he noted, and simply crawl along the seafloor rather than pursuing anything resembling a hunt on the ground.
That lifestyle has practical consequences, starting with the question of whether the discovery poses any risk to people. It does not. These animals are fully marine; they are not adapted to rooms, floors, or any other terrestrial habitat, and the specimens in question came from waters between Washington and British Columbia, not from a coastline where beachgoers or homeowners would encounter them. The novelty is taxonomic rather than menacing: this is science cataloguing organisms that have been present in coastal waters all along, largely unobserved.
One of the two new species, *Tanystylum kiixin*, was photographed by Toler-Scott with round eggs carried inside its legs — a striking image that captures how much of sea spider biology takes place within the framework of the animal's own body. A widely circulated photograph from the research, credited to Cormac Toler-Scott and the University of British Columbia, shows the small-bodied spider holding a cluster of eggs, offering a rare glimpse of reproductive behavior in a group that is notoriously difficult to observe up close.
The other species, *Callipallene pilosuspedes*, is described in more anatomical detail. According to the research, it has red eyes, a three-lipped mouth shaped like a triangle, and a curved spine that covers its legs. It also bears limbs that grow from the underside of its body, called ovigers, which the animal uses to groom itself and comb off dirt. These are the kinds of fine-grained characters that matter in the naming of a new species: because many sea spiders look broadly similar at a glance, taxonomists rely on details of mouthparts, spines, leg joints and appendages to distinguish one population from another.
That focus on small details helps explain the timing of the discovery. More than 100 years passed between the last sea spider found in the Salish Sea and these two, and the gap is less a sign of biological absence than of limited sampling. Slow-moving, centimeter-sized animals that live on the seafloor are easy to walk past — or to extract from a bottom sample and mistake for something unremarkable. A survey that brings a trained eye, and dissection tools, to a single stretch of coastal water can turn up animals that decades of casual collecting missed.
The broader picture is one of an ocean still being inventoried. With well over 1,300 sea spider species named and the total only estimated to grow, researchers continue to argue that the ocean's species count is far from complete. The Salish Sea, a semi-enclosed and biologically distinctive coastal system, had gone a century without a new local record, and now has two at once — evidence that sustained fieldwork, rather than a single dramatic expedition, is what produces results of this kind.
For Toler-Scott and his colleagues, the discovery is a reminder of how incomplete the map of marine biodiversity remains, and how many ordinary-looking creatures on the seafloor remain formally unidentified. Each described species also becomes a reference point: a baseline record that lets scientists track where populations live, how they reproduce, and how coastal habitats change. For everything else, the finding is a small, slow-moving curiosity of the Salish Sea — real, and scientifically valuable, but entirely at home in the water.
(0)