Every Thursday, Laboratory Equipment features a Scientist of the Week, chosen from the science industry’s latest headlines. This week’s scientist is Duncan Leitch from Vanderbilt Univ. He and a team found that alligators and crocodiles have an incredibly keen sense of touch.
Q: What made you interested in studying the crocodilian sense of touch?
A: I have always been fascinated by being in nature and looking at all kinds of animals – especially reptiles and amphibians. Thankfully, my parents were supportive of these interests and got me field guides and let me keep small turtles and lizards. As a neuroscience undergraduate student, I saw a very interesting video (from the work of Daphne Soares) of an American alligator orienting towards the ripples generated by a single droplet of water. This suggested that the bumps on the faces of alligators, which are also called integumentary sensory organs or ISOs, were tactile, but a lot of other ideas had been discussed in the literature. Could they sense electric fields like sharks and the platypus? Could they serve a function in sensing magnetic fields like in some birds? Did they detect changes in salinity that a crocodile might encounter as it moves from fresh to saltwater? There seemed be a lot of room to investigate some interesting questions.
Q: What are the future implications of your research and findings?
A: Foremost, I hope that people appreciate crocodilians as the beautiful (or at least, intriguing) creatures that they are. There are a lot of very similar specialized mechanoreceptor nerve endings to those found in human skin so it would be very interesting to compare these peripheral nerves and their physiology. Also, crocodilians occupy a unique (and somewhat understudied) spot within evolution. They are actually more closely related to birds than they are to other reptiles like lizards and snakes. It would be great to continue to see where these sensory specializations of their nervous system fit within the greater scheme of brain evolution and development.
Q: What was the most surprising thing you found in your research?
A: Getting to work with them this long, I have been consistently impressed by how intelligent they seem and now we know that they are as sensitive as we are, at least in terms of touch. The make all sort of vocalizations to call to one another or to their mothers as hatchlings. They are definitely among the most “social” of the reptiles, with the mother crocodilians displaying some degree of maternal care in guarding the nest and helping the babies hatch from their eggs. And then, they use the very same teeth and jaws to overwhelm large prey. It was surprising to figure out how sensitive they were and next to think about the possible roles for this sensation in these otherwise scaly, armored animals.
Q: What is the take home message of your research and results?
A: There’s a whole universe of questions just waiting to answered, and if you look really closely at anything – from a single protein to a whole ecosystem – there will be neat things to find out that will give us a better sense of our world. I’ve been fortunate enough to get to look very closely at alligators and crocodiles, as well as a host of other animals, but I hope that people have the freedom to go over their own ideas and hypotheses and enjoy the adventure of discovery.
Q: What new technologies did you use in your lab during your research?
A: Working with creatures that are not often used in research, we had to improvise and make a lot of the instruments we needed. It was very helpful to have a PowerLab data acquisition system to simultaneously record the movement of a touch stimulus with neuronal activity. Also, using the different scanning electron microscopes, I was able to examine the external surface of the crocodilian skin in great detail.
Q: What is next for you and your research?
A: I hope to continue to study interesting groups of animals, including the crocodilians, and more specifically to investigate representations of other sensations in different parts of the brain. Although modern crocodilians are certainly not the ancestor to humans, it would be interesting to get the chance to see what parts of the brains of these two very different groups are similar. Also, I think that with the exponential growth in areas of molecular biology and genomic analysis that there could be some room for exciting work comparing vertebrates in a variety of different ways.