Pycnogonum stearnsi, commonly known as Stearns' sea spider, is a marine arthropod in the family Pycnogonidae.

It does not have the chelicerae or pedipalps typical of sea spiders but uses its barrel-shaped proboscis for feeding.

[1] It is most common in California,[2] and is found from the mid shore down to low water mark.

The male then collects the eggs and presses them against his ovigerous legs where they adhere, forming a large white mass which he carries around.

These moult several times, passing through further nymphal stages before developing the proboscis and feeding method of the adult.