Researchers discovered two new sea spider species measuring about a centimeter across in shallow waters between Washington State and British Columbia, marking the first such discovery in the Salish Sea in over a century.
Salish Sea Expeditions Yield First Sea Spider Discoveries in Over a Century
Marine researchers exploring the Salish Sea between Washington State and the Canadian province of British Columbia have uncovered two new species that belong to the sea spider family. Collected between September 2023 and August 2024 off the islands of Vancouver and Quadra in British Columbia, the specimens measure roughly a centimeter across.
These tiny marine arthropods represent the first sea spider species found in the region in more than 100 years, according to the researchers. Sea spiders form part of a class known as Pycnogonida, with scientists having cataloged more than 1,300 species globally.
Physical Traits and Grooming Habits of Callipallene pilosuspedes and Tanystylum kiixin
Although they share a common evolutionary background and an eight-legged body plan with terrestrial spiders, Cormac Toler-Scott—the lead researcher of the University of British Columbia team that uncovered the new species—explained to NPR that sea spiders stayed strictly aquatic.
They never made that transition to land,
Toler-Scott said. They really need to be in the water. They're quite slow moving. They just kind of crawl on the seafloor.
The team identified the first new species as Callipallene pilosuspedes. This creature features red eyes, a triangular three-lipped mouth, and a curved spine covering its legs. It also possesses limbs that come from its belly called ovigers.
Those specialized belly limbs can be used to groom itself and comb off dirt as well as algae. They're very clean and not all sea spiders can do this,
Toler-Scott said regarding Callipallene pilosuspedes.
The second new species, Tanystylum kiixin, takes its name from an ancient Indigenous village near where it was found. It features shorter and stockier legs coming out of its chest that can’t be used to clean themselves. When found, the Tanystylum kiixin was covered in dirt and debris, according to Toler-Scott.
Feeding Mechanisms, Reproduction, and Future Dives
Unlike terrestrial spiders, reproduction in sea spiders involves the females producing eggs while the males assume full responsibility for tending to the offspring until hatching occurs.
Rather than spinning webs to catch meals like land-dwelling spiders do, these newly discovered specimens were discovered clinging to a colony-forming, plant-like marine organism known as a hydroid.
“They’re both living on that and feeding on that, kind of walking through it like a maze, and they just kind of poke a hole into the hydroid itself, and then they suck the juices out of it, like the cells out of the hydroid. That’s how they get their food,” Toler-Scott explained.
Lacking venom or fangs, the newly discovered species mainly rely on camouflage to avoid being eaten. He pointed out that numerous sea spiders, including these recent finds, are see-through and adopt the hue of their most recent meal.
It's everyone's kind of dream to find new species, but it's pretty uncommon,
said Toler-Scott. It's hard to get funding for this kind of work because you go into it not really knowing what you're going to get.
As the University of British Columbia investigators prepare further underwater excursions, they anticipate uncovering additional varieties of sea spiders down the road.