Sea spiders breathe through their skin, and it is the males, not the females, who rear the young. Females carry ovaries distributed throughout their limbs, producing eggs that emerge through a dedicated pore. During mating, males use a specialised pair of limbs called ovigers, positioned at the base of the head, to collect the eggs, coat them in a glue secreted from their legs, and attach them to their own bodies in clusters for rearing.
The newly described species were collected between September 2023 and August 2024, during dives to depths of up to 18 metres across a range of habitats, including sites at Quadra Island, Vancouver, Bamfield and Victoria.
The first, Callipallene pilosuspedes, is named for the long, curved spines covering its lower legs – a nod to the Latin for “hairy feet.” It has red eyes, a short claw-tipped proboscis for grasping food before biting, and a triangular, three-lipped mouth lined with sensory tendrils. It also possesses unusually dexterous ovigers, which researchers observed being used as grooming tools, wrapped around the legs to sweep away debris with attached comb-like spines. Only a single specimen of the species has so far been found.
The second, Tanystylum kiixin, takes its name from the ancient Indigenous village site near where the first specimens were collected. Pronounced “kee-hin,” the name derives from the sound of waves breaking at the base of the village site. Unlike its counterpart, this species has smaller, less dexterous egg-carrying limbs and is unable to groom itself effectively – researchers frequently found it coated in debris and playing host to its own tiny parasites, forming what Toler-Scott describes as “an ecosystem within an ecosystem within an ecosystem.”
The study represents the first comprehensive assessment of sea spiders in the Salish Sea to combine detailed imaging with DNA analysis. In the process, the team generated genetic data for several previously unsequenced species and produced an identification guide for sea spiders in the region.
Both new species have been registered in a global taxonomic database, but Toler-Scott believes many more remain undocumented. “I only had one field season but there’s definitely more diversity out there that we haven’t documented.”