Scientists in Canada have identified two new species of sea spiders within the Salish Sea, a body of water situated between Washington State and British Columbia. The discoveries, which represent the first time members of this order have been found in the area in over a century, were made by researchers at the University of British Columbia.
The new specimens, measuring approximately one centimeter across, were collected from September 2023 to August 2024 near Vancouver and Quadra islands. Despite their name, these marine arthropods of the class Pycnogonida do not resemble terrestrial spiders in behavior or habitat. “They never made that transition to land,” explained lead researcher Cormac Toler-Scott. “They really need to be in the water. They’re quite slow moving. They just kind of crawl on the seafloor.”
One of the newly described species, Callipallene pilosuspedes, features distinctive red eyes, a triangular three-lipped mouth, and a curved spine running along its legs. It also possesses specialized limbs known as ovigers, which it uses for grooming. Toler-Scott noted that the species keeps itself remarkably clean, using these appendages to remove dirt and algae—a trait not shared by all sea spiders.
The second species, Tanystylum kiixin, was named in honor of an ancient Indigenous village located near the discovery site. This species is characterized by shorter, stouter legs extending from its chest and lacks the grooming appendages found in C. pilosuspedes. Upon collection, Toler-Scott observed that T. kiixin was covered in debris and dirt.
Unlike their land-dwelling relatives, sea spiders do not construct webs or use venom. Instead, the newly found species feed by attaching themselves to hydroids, colonial marine animals that resemble plants. They pierce the hydroid’s cells and suck out the juices, effectively living within the structure like a maze. To avoid predators, these spiders rely on transparency and camouflage, often taking on the color of the organisms they consume.
Reproduction also differs significantly from terrestrial spiders. While females produce the eggs, males assume the primary responsibility for carrying and protecting them until they hatch.
Toler-Scott acknowledged the challenges inherent in such research, noting that funding is difficult to secure for work with unpredictable outcomes. However, with additional diving expeditions planned, the team anticipates further discoveries of sea spider species in the region.
Crawling around Vancouver Island sounds creepy, but totally worth it for a century-first discovery. Nature never stops surprising us.
I had no idea male sea spiders carried the eggs! That seems backwards compared to almost every other arachnid.