This week I’ve been feeling a lot like the very planktonic larva I have been studying: drifting in a general direction, waiting for the right place to settle.
To my dismay, Ostrea lurida, the Olympia oyster, does not seem to be a reliable source of larva at this point in the season. After opening 10 more organisms and finding none containing larva, I had to forfeit the hope of using them as the subject for my summer project. It was back to the drawing board to find a suitable brooding species.
What is a brooder? And why must I select one? Brooding refers to the act of incubating one’s fertilized eggs within the body wall until they reach a certain developmental point, then releasing them into the environment. By selecting a brooder, I can acquire a large number of larva from one individual, and if I can identify the species of the adult from which the larva came, I will know exactly what organism I am studying. The alternative would include the extra step of filtering free-swimming larva from the plankton then having to identify that organism. This can be a painstaking process as many larval organisms do not have well-defined characteristics at such an early stage in development.
Enter the shipworm, Teredo bartschi. Not the first organism that comes to mind when one thinks of bivalves. The shipworm is not a worm at all, but is named as such due to its worm-like body that is not covered by a shell, as bivalves typically are. Its valves (shells) are found at the anterior tip of the body and have been modified to burrow into submerged wood. Their ability to effectively turn a solid piece of wood into swiss cheese has been well documented. In 1588, the shipworm species Teredo navalis is credited with weakening the wooden ships of the Spanish Armada giving England an advantage that eventually led to the armada’s defeat.
My mentor, Richard, and I set out a mission to collect wood samples containing T. bartschi in nearby Haynes Inlet. Thus far, the shipworm has been much more cooperative! Extracting them from the wood is a challenge, as their bodies are extremely delicate, but five of the six I managed to collect contained larva in various stages of development. I am interested in the settlement and metamorphosis of larva, and experimenting with different salinity levels. At last, I have found an organism to use as my research subject. I have settled, and now I can begin my observations.
It’s not all work here at OIMB. Last Friday the REU interns, along with my mentor Richard and two graduate students, Nicole and Makenna, went on a dredging trip aboard OIMB’s research vessel R/V Pluteus. Captain Knute even let me steer the boat! Among our haul were numerous sea cucumbers, basket stars, brittle stars, and crab. The sun shone brightly for our entire outing and an afternoon on the water was the perfect way to celebrate the end of a great first week here at OIMB!