Scientists Discover Two New Sea Spider Species After Nearly a Century

Scientists have discovered two previously unknown species of sea spider in the Salish Sea along the Pacific coast of North America, marking the first time in almost 100 years that new sea spider species have been formally described from the region.

The discovery was made by researchers from the University of British Columbia, who studied specimens collected during scuba dives between September 2023 and August 2024. Their research was published in Organisms Diversity & Evolution.

One Species Has Hairy Legs and Red Eyes

The first species, Callipallene pilosuspedes, is notable for the long spines covering its lower legs. Its name refers to its unusual “hairy feet.”

The tiny animal also has striking red eyes and a short feeding structure called a proboscis. Researchers observed that it uses specialized limbs to groom itself, combing debris from its body.

Only one specimen of this species was found during the research, making the discovery particularly valuable for scientists studying the biodiversity of the region.

The Second Species Carries Its Eggs Differently

The second species, Tanystylum kiixin, was named after an Indigenous village site near where specimens were first collected.

Unlike the first species, its egg-carrying limbs are smaller and less capable of grooming. Researchers found that some individuals were covered with tiny parasites, creating what the scientists described as an “ecosystem within an ecosystem.”

Sea Spiders Are Not Actually Spiders

Despite their name and appearance, sea spiders are marine arthropods rather than true spiders. They are distantly related to groups that include spiders, scorpions and horseshoe crabs.

Some sea spiders are less than a centimetre long, while species found in Antarctic waters can be much larger. They use a tube-like proboscis to feed on soft-bodied marine animals and have unusual reproductive behaviour: males carry and care for the eggs after females produce them.

Scientists Believe More Species Are Waiting to Be Found

The researchers examined seven species as part of the first comprehensive study combining detailed anatomical imaging and genetic analysis of sea spiders in the Salish Sea.

The work also produced new genetic information for several species and an identification guide that can help researchers distinguish sea spiders found in the region.

Lead researcher Cormac Toler-Scott said the discovery suggests there may be considerably more diversity in the Salish Sea that scientists have not yet documented.

For researchers, identifying these small and poorly understood animals is an important first step toward understanding how marine ecosystems respond to climate change and human disturbance.

Sources

• University of British Columbia — “Hairy-legged red-eyed sea spiders discovered in the Salish Sea” — September 23, 2026.
• Organisms Diversity & Evolution — “Sea spiders of the Salish Sea: Comparative morphology and molecular phylogenetic analysis of seven coastal species” — 2026.
• PEOPLE — “Scientists Discover 2 Bizarre Sea Spider Species Off North America’s Pacific Coast, the First in Almost 100 Years” — September 30, 2026.