Seeing the Light
The Wonderful Diversity of Light Perception in Living Organisms
Many of us are certain that human eyes are at the evolutionary apex of animal vision. While we have rather good general purpose vision - able to see a speck of dust on the window, provide a full experience of color space, sense motion so quick that we can (some of us) successfully hit an approaching fastball out into the bleachers, visualize a world lit with brilliant sunshine or dim starlight, move rapidly from an interesting object to another one far from it, and capture all the information in a scene - other animals badly outperform us in every one of these abilities, and many in several of them - with each of their eyes at the same time.
New imaging technologies and high-speed computers make it possible to enter the visual worlds of species who see things very differently from the way we do. This talk will discuss the visual capacities of other species, ranging from deep-sea shrimp ,who have no optics in their eyes yet see the hot water emerging from hydrothermal vents, to the many creatures that see ultraviolet light or image polarization patterns such as those a potential mate flashes when courting. Much of the talk will be devoted to the astonishing eyes of the mantis shrimps. These creatures have two independently moving eyes that can see color both in the range of light that we experience and in the ultraviolet. They can also visualize two different kinds of polarized light, and either eye by itself can measure distance. The talk will employ a variety of imaging techniques to illustrate in a way we humans can see, if only crudely, the visual worlds inhabited by other animals.
About the Speaker
Tom Cronin studies the visual physiology of invertebrates, especially marine and estuarine crustaceans. His research group’s motto is “If it has eyes, we can study it!” In recent years, his group has published papers on vision in squids, butterflies, fiddler crabs, cuttlefish, primates, dolphins, orioles, reef fishes, sponges, right whales, poison-dart frogs, fireflies, octopus, deep-sea crabs, whooping cranes, and mantis shrimp.
Most of Tom’s recent work has been with the mantis shrimps (stomatopods), a unique group of tropical crustaceans that have extremely complicated behavior and perhaps the most unusual eyes ever evolved. In particular, he has been studying their color vision systems (which have many as 16 spectral channels), their photic environments, their systems of color communication, the dynamics of their photoreceptor cells, and their ocular movements and control systems. He and his research group also have begun studying molecular genetics of mantis shrimp opsins, the photoreceptor proteins that underlie the visual detection of light in these organisms. The goal of this research is to learn how the photoreceptors evolved and how these visual proteins are specialized for color vision and for seeing the polarized-light signals that many species of mantis shrimps produce.
Tom has published numerous papers on his research on the visual systems of animals ranging from sponges to humans, with the main corpus of his publications focusing on marine invertebrates. He also is co-author of the authoritative text Visual Ecology.
Among other honors, Tom is an elected Fellow of the AAAS and of the International Society for Neuroethology.
Tom earned a PhD at Duke University and then did postdoctoral work with Timothy Goldsmith at Yale University before joining the faculty at UMBC.