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By Melissa Olguin, FSU undergraduate

An Arca zebra shell with many different types of organisms attached. The peach colored flatworm is probably in the family Stylochidae, which is common in shallow areas of the Gulf of Mexico, usually near oyster reefs.

An Arca zebra shell with many different types of organisms attached. The peach colored flatworm is probably in the family Stylochidae, which is common in shallow areas of the Gulf of Mexico, usually near oyster reefs.

If you have a thing for invertebrates, then this project will give you a shell of a good time. I’m Melissa, a fourth year undergrad working in Dr. Brooke’s lab. I’m looking at the epibiont communities forming on a local bivalve, the Arca zebra, commonly called the Turkey Wing Clam. In the field these shells often look like little more than small clumps of sediment. But upon closer inspection one can find a slew of colorful motile and sessile organisms calling these shells home. Each shell appears to have its own community of encrusting, branching, and crawling organisms. Currently I’m recording and identifying the organisms growing and living on each shell.
Two large Arca zebra covered in epibionts, including algae, coralline algae, tunicates and several cup corals called Phyllangia americana. We don’t know how long these bivalves live, but they must be quite old as these corals grow slowly.

Two large Arca zebra covered in epibionts, including algae, coralline algae, tunicates and several cup corals called Phyllangia americana. We don’t know how long these bivalves live, but they must be quite old as these corals grow slowly.

This process has exposed me to a lot of taxonomical work and even revealed to me the amount of work still needed for the Gulf of Mexico. One such example is demonstrated in the photo showing a peach colored flatworm. Much of the literature on Atlantic flatworms is old, and my main resource on the Gulf of Mexico for flatworms only has depth records of only 4 m for most species. That puts my flatworm (collected at 12m) beyond its recorded depth. This finding shows that in understudied habitats like the Apalachee Bay nearshore reefs, a little exploration can produce valuable new information, such as depth extensions in the case of my flatworm.

Besides looking at what is living on these shells, I am interested in seeing the interactions going on between the epibionts and the Arca zebra. Epibionts have been found to deter predation on bivalves (Vance 1978) while the Arca zebra shells can provide the substrate necessary for many organisms to settle on (Scandland 1979, Avila et al 2013). I would love to explore this more and I’m looking forward to discovering more about these fascinating communities.

References:

Hernández-Ávila, I., Tagliafico, A., & Rago, N. (2013). Composition and structure of the macrofauna associated with beds of two bivalve species in Cubagua Island, Venezuela. Revista de Biología Tropical, 61, 669-682.

Scanland, T. B. (1979). Epibiota of Arca zebra and Arca imbricata– Community Analysis. Veliger, 21, 475-485.

Vance, R. R. (1978). A mutualistic interaction between a sessile marine clam and its epibionts. Ecology, 679-685.