It was interesting to see this swimming winged sea slug (Gastropteron pacificum) with its wings fully extended. This small animal was a rare find for me and spotted at Nanoose Bay. The winged sea slug is a strong swimmer, and its wings (parapodia) are extensions of its foot. The winged sea slug grows to only 1.6 inches (4 cm) long, with a range from northern Alaska to northern Mexico, as well as the Galapagos Islands.