A Very Unusual Clam
In 2015, M.G. “Jerry” Harasewych, a research zoologist at the Smithsonian National Museum of Natural History, and Ilya Tëmkin, then a postdoctoral fellow in that institution, named a new species of file clam, Mantellina translucens, a species living in moderately deep-water (around 200–300 m, or about 660–990 ft) off Curaçao, in the southern Caribbean Sea. The species name reflects the translucent nature of is delicate shell, which reaches about 41 mm (about 1.6 inches) in size. Remarkably, prior to this discovery, the genus Mantellina was known until only from fossil shells from the Miocene epoch, in this case around at least 16 million years of age. In their article, Harasewych and Tëmkin used DNA sequencing to confirm the allocation of the genus and species to the bivalve family Limidae, the file clams. They examined the internal anatomy of that species, proposing that its digestive tract hints at omnivory, in this case a combination of the “usual” filter-feeding common to bivalves complemented by the ingestion of small invertebrates. Their article, published in the Journal of Molluscan Studies, shows excellent pictures of the living clam with its long and delicate tentacles completely distended. Read the article here.