Researchers at the University of British Columbia have identified two previously unknown species of sea spider in the Salish Sea, marking the first new formal descriptions of these marine arthropods from the region in nearly 100 years. The findings, published in the journal Organisms Diversity & Evolution, offer new insights into the strange biology and hidden diversity of these ancient creatures.
The study highlights one species, named Callipallene pilosuspedes, which features long, curved spines on its legs—referencing the Latin for “hairy feet”—striking red eyes, and a triangular mouth surrounded by sensory tendrils. Its appearance has led some to compare it to a tiny marine version of the fictional Sarlacc pit from Star Wars.
“I was interested in how sea spiders are impacted by climate change and human disturbance, because marine invertebrates in the Salish Sea are particularly at-risk, and I couldn’t find anything,” said lead author Cormac Toler-Scott, who completed the work as part of his master’s degree in zoology at UBC. “That’s largely because people don’t know much about what species exist here and what their lifestyle is.”
According to Toler-Scott, this lack of basic taxonomic knowledge affects many marine arthropods. “In order to understand how marine invertebrates are being impacted by things like climate change and how we can better protect these key elements of the ecosystem, we have to be able to identify them,” he noted.
Sea spiders belong to an ancient lineage that emerged approximately 500 million years ago, closely related to spiders, scorpions, and horseshoe crabs. Unlike their terrestrial relatives, they have remained exclusively marine. Their morphology is unusual even among arthropods: some species possess up to 12 legs and a sucking proboscis for feeding. Sizes vary dramatically, ranging from less than a centimeter to over 70 cm in Antarctic waters, where larger species may hunt smaller animals.
“They’ve retained some weird traits,” Toler-Scott explained. “A lot of the shallow water species are quite small, and so they’ll live as parasites on larger organisms, and they use this weird apparatus called a proboscis to suck the juices out of their host.”
The second newly described species, Tanystylum kiixin, was named after an ancient Indigenous village site near where specimens were found. The name, pronounced “kee-hin,” references the sound of waves crashing against the base of the village. Unlike its counterpart, this species has smaller, less flexible egg-carrying limbs, which limits its ability to groom itself. Researchers frequently observed dirt, debris, and tiny parasites clinging to the animals.
“The result is what Toler-Scott describes as ‘an ecosystem within an ecosystem within an ecosystem.'” Despite its memorable appearance, only a single specimen of Callipallene pilosuspedes was found during the study period between September 2023 and August 2024. Specimens were collected from depths of up to 18 meters around Quadra Island, Vancouver, Bamfield, and Victoria.
Remarkably, under microscopic observation, researchers watched C. pilosuspedes use its agile ovigers—not just for carrying eggs, but also to wrap around its legs and comb-like spines to groom its body.
The research combined detailed physical imaging with genetic analysis, generating DNA sequences for several species never before sequenced. An identification guide was also produced to help scientists distinguish sea spider species across the region. Both new species have been registered in a global database.
Toler-Scott cautioned that the Salish Sea likely holds more undocumented diversity. “I only had one field season, but there’s definitely more diversity out there that we haven’t documented,” he said. In other words, the ocean may still be hiding additional examples of what he humorously termed “nightmare fuel.”
This research was funded by the Natural Sciences and Engineering Research Council of Canada.
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