A pair of species unknown to science has been described from the shallow coastal waters of British Columbia, giving researchers their first documented encounter with a sea spider in the Salish Sea in more than 100 years. The finds, announced by a team at the University of British Columbia, are the first new sea spider species described from the region in living memory, and they suggest the marine life of the inland sea between Washington State and Vancouver Island is far less thoroughly cataloged than anyone assumed.
The animals were collected over roughly a year, between September 2023 and August 2024, from shallow water off the islands of Vancouver and Quadra, two of the larger islands in the Salish Sea. Both new species measure about a centimeter across — smaller than a fingernail — which is typical for their group and one reason they have so often gone unnoticed in places where people dive, fish and collect.
Cormac Toler-Scott, the lead researcher on the UBC team, said the discovery surprised the group in more than just taxonomic terms. "They never made that transition to land," he told NPR, explaining that sea spiders look like their eight-legged terrestrial cousins but belong to a separate evolutionary branch. "They really need to be in the water. They're quite slow moving. They just kind of crawl on the seafloor."
Sea spiders, or pycnogonids, are marine arthropods classified in a class of their own, Pycnogonida. Scientists have named more than 1,300 species, and they range from intertidal pools to the deep seafloor, living on or near organisms such as hydroids, anemones, soft corals and small crustaceans. Despite their spider-like appearance, they differ from land spiders in ways that go far beyond habitat: their body proportions, their internal anatomy, even the way fluids move through them are unlike those of true spiders.
One of the two new species, *Callipallene pilosuspedes*, was described in detail in the report. According to the researchers, it has bright red eyes, a three-lipped mouth shaped like a triangle, and a curved spine that extends over and covers the legs. It also bears a set of appendages that grow from the underside of the body, called ovigers, which the animal uses for grooming and combing debris from itself — a trait common across the group.
The second species, *Tanystylum kiixin*, is known from a photograph taken during the study, which shows a living specimen with round eggs nestled inside its legs. Carrying egg masses is a distinctive feature of pycnogonids, and the placement of the eggs in the photograph offers a glimpse of the reproductive biology of a group that remains poorly documented in the wild. The images accompanying the findings are credited to Toler-Scott and the University of British Columbia.
The gap between the collections of these animals and the previous record in the area is what makes the discovery notable. Sea spiders are not migratory and do not range widely across ocean basins, so a century without a recorded specimen in a well-visited coastal region points to sampling gaps rather than a genuine absence. Shallow subtidal rocky habitat along island edges is difficult to survey systematically, and animals that are a centimeter long, slow-moving and camouflaged against encrusted surfaces are easily overlooked.
The Salish Sea itself is a semi-enclosed body of water linking the Strait of Georgia, the Strait of Juan de Fuca and Puget Sound, shaped by glaciation and known for its large tidal range. It is among the most heavily used coastal waters on the Pacific Northwest, yet much of what lives on its bottom remains unexamined. Each time a species is described from such a place, it enlarges the map of regional biodiversity and gives scientists a baseline for tracking change in marine habitats under mounting pressure from development, fishing, warming waters and acidification.
Formally naming a species matters for more than bookkeeping. Descriptions are what allow researchers to distinguish one population from another, map ranges, track declines and design protection. If the last century of records missed two species, it is reasonable to assume other small, cryptic or rarely collected animals are present and unnamed as well. Descriptions of this kind also give other groups a reference point, allowing later work on distribution, behavior and relationships within the family.
The team expects that more sampling of Salish Sea shallows will turn up further surprises. For now, the two new species stand as a reminder that the most familiar-looking animals on a shoreline can still hide significant unknowns, and that a working checklist of marine life remains a long way from complete. As Toler-Scott put it in describing the group overall, these creatures do not wander into homes or spin webs in living rooms — they stay in the water, moving slowly across the seafloor, doing the quiet work of being part of a food web that researchers are only beginning to map.
(0)