Scallops Have Charming Eyes
One of the presentations that caught my fancy during the World Congress of Malacology last week, in Pacific Grove, California, was given by Daniel Speiser from University of South Carolina. Speiser spoke about the eyes of scallops, focusing (pardon the pun) on the Atlantic Bay Scallop, Argopecten irradians, and the Atlantic Sea Scallop, Placopecten magellanicus. Scallops have a large number of small eyes deployed along the edges of their shells; Atlantic Bay Scallops have eyes of a brilliant blue color. Both species have complex eyes that include a cornea, lens, retina, and a concave, image-forming mirror. In addition to these features, the two species studied by Speiser are capable of narrowing their eye pupils to about 60% of their fully dilated areas within a few minutes of exposure to light. A constricted pupil may help increase the level of detail in their vision. Another cool finding explained by Speiser is the origin of the blue color of the Atlantic Bay Scallops and other blue-eyed scallops: blue-color nanospheres that may help increase image contrast in the eyes of that and other blue-eyed scallop species. The illustration of a cross-section of the eye of an Atlantic Bay Scallop was adapted from Speiser’s recent presentation and from a 2011 paper by him and co-authors.