Fast-Paced Research on Slow Animals
Growing up on the Florida Gulf Coast, I loved to explore the coastline and to collect shells never thinking that these childhood experiences would become the basis for my professional passion in life. As I grew older, I began learning more about these shells and the animals that make them.
Most of my research involves marine snails such as whelks, conchs, limpets and abalone, as well as the relationship between structure and function in these organisms. Engineered materials are usually designed to carry out a single function under specified conditions. Biological materials, in contrast, have been modified by millions of years of natural selection as compromises to diverse internal and external forces. They usually carry out multiple functions, none of them perfectly. In my research, I test hypotheses about the functions of biological structures with the goal of understanding their evolution.
Each snail crawls on a single, muscular foot, which is what we eat as conch fritters or awabi sushi. For my doctoral dissertation I studied locomotion in marine snails, especially whelks and abalone, which involved describing the basic anatomy and histology of their muscle and connective tissue, and recording the pressures generated inside their feet as they crawled.
Over the years my interest has broadened to include another set of structures of marine snails, the gills, which are the feather-like sites of gas exchange. Underlying the shell is the mantle cavity, which houses the gills and other structures that serve as the link between the animal’s organ systems and its environment. Because these structures are housed within a hard shell, it has been difficult to watch them as they function. Most studies, therefore, have focused on dissections or studies of preserved animals. Over time, however, I have developed a set of tools to learn more about how the gills function in the living animal. For example, I have used a laser beam as a light source to record the movement of tiny particles traveling in and out of the mantle cavity. By measuring the sizes of the anatomical spaces through which the particles travel, I have been able to estimate the rates at which water passes through the gills of different species of snails.
Most recently, I have been using an endoscope to observe the movements of the gills in living keyhole limpets and abalone. These animals have naturally occurring openings on the upper surfaces of their shells. Many people have had experiences with endoscopy and colonoscopy. Imagine the size instrument I use to examine these creatures’ structure. Abalone average five to six inches in length. The instrument I use is similar to the one used for human colonoscopies, but simpler and smaller, less than two millimeters in diameter. I can insert the endoscope through an opening in the shell of a live animal without damaging the shell or underlying tissue. The most difficult part is getting the animals to cooperate. Each snail is set in a dish of seawater that is only slightly larger than the animal itself. They are free to crawl around the dish and often do. I am one of the few people in the world who wish snails would move more slowly! What I have observed has never been described before: the gills are very dynamic and filled with blood so that they resemble delicate balloons. Muscles in the walls of the gills permit them to contract and re-expand to fill the mantle cavity. As my research continues, I will analyze the videotapes I recorded of the movement of water and particles through the gills and mantle cavity with the longterm goal of understanding the evolution of these structures.
Why conduct studies such as these? To examine and understand the diversity of life on earth. It is fascinating to see the amazing diversity of animals, and to examine all the different ways animals function and the structures that enable these functions.
I seek to understand evolution one snail at a time.