Bivalves, brachiopods, and gastropods, oh my: three investigations into the morphology, physiology, and taphonomy of shelled invertebrates near Friday Harbor Laboratories, Washington, USA

Abstract

I completed three research projects as part of the Summer 2025 Marine Invertebrate Zoology course. First, generating (to my knowledge) the first contrast-enhanced scan of a brachiopod, Terebratalia transversa, to visualize soft tissues. The specimens were stained in 1.75% Lugol’s iodine in Sorensen’s buffer for 48 hours, allowing for visualization of structures such as the lophophore, gonads, digestive tract, and shell adductor and abductor muscles. Second, I conducted an experiment investigating filter feeding rates in the brachiopod Terebratalia transversa and the bivalve Mytilus edulis under turbid conditions. Preliminary results suggest that both brachiopods and bivalves engage in particle sorting during filter feeding and that Mytilus is more effective at removing particles from suspension, although the latter finding was not statistically significant. Finally, I compared and analyzed a living and dead assemblage from a dredge sample taken from a shell gravel in San Juan Channel. I found that rank correlation between the live and dead assemblages was weak, but Chao-Jaccard similarity was high. These findings indicate that the death assemblage in this sample has high fidelity with respect to species diversity, but low fidelity with respect to relative abundance. The disagreement in rank abundance appears to be largely driven by rapid destruction of shells from thin-shelled gastropods such as Calyptraea fastigiata, Crepidula perforans, and Hipponix cranioides.