On a recent bright but overcast Saturday, divers explored under the dock in Tramp Harbor, searching for critters to share with the visitors on the wooden deck above.
Called “Who Lives Under the Dock?” it was another in a series of events organized by the Vashon Beach Naturalists to bring the public up close and personal to the interesting characters that live near and on our shores. We met a variety of creatures great and small, ornate and plain.
Naturalists filled glass aquariums and created touch tanks out of plastic wading pools where visitors could explore the elements of habitat as well as living creatures. A favorite with the kids, the touch pools were filled with shells, seaweed, sea snails, sea stars, at least seven kinds of crab and the largest California sea cucumber any of us had ever seen. According to the field guide “Whelks to Whales,” they can grow as long as 20 inches, though it seemed to me that this one was even bigger.
The California sea cucumber is common and harvested commercially by some Asian cultures that consider it medicinal and a delicacy. Sea cucumbers are remark-able in that when they feel threatened, they can eviscerate themselves. Just like a lizard dropping its tail, sea cucumbers can empty their guts into the water to distract a predator. Although they certainly survive such a tactic, it can take about two to five weeks to re-grow their viscera. To avoid this, the naturalists encouraged gentleness towards the one the divers found. However, researchers have shown that these sea cucumbers in the wild will seasonally expel their entrails. Its nature’s version of the fall cleanse.
On the other side of the size spectrum, the smallest creature found that day hitched a ride on some sand and shell fragments brought up from the bottom — a barnacle-eating dorid only millimeters long. Dorids are a type of nudibranch, or sea slug, that breathes through the feathery gills they wear on their back. They can be colorful, like the yellow sea lemon, or speckled like the heath’s dorid, whose white body seems spotted with flakes of pepper.
The few fishes that populated the glass aquariums got a lot of attention from visitors. A juvenile sole swam along the bottom of the tank, camouflaging well with the beach rock, sand and shell fragments. Like flounder, sole are flat fish with both eyes on the same side of their head.
An eel-like gunnel spent most of its time hiding near a barnacle-covered rock. But the most attractive animal award was won that day by the sailfin sculpin — an entrancing swimmer with a very tall, sail-like fin behind its head. This fish was a handsome little creature and only half-grown at approximately 4 inches. Its scientific name is Nautichthys oculofasciatus; Nauti means sail, and oculofasciatus refers the dark band through its eye. When it swam, it undulated its shorter dorsal fin akin to a waving flag. Normally only observed by divers at night, this nocturnal fish is a popular aquarium species because it does well in captivity. We considered ourselves especially lucky to have met such a charming little fellow.
— Adria Magrath is a biologist, teacher and nature photographer, as well as a Vashon Beach Naturalist.
