This post is part one of a series of guest post by Kevin Wolfe, a 2nd year PhD student at Texas A&M University- Corpus Christi, writer for Charged Magazine, co-founder of ScienceisFunnyFilms, and writer of funny Princess Bride related titles.
I make my living torturing snails and playing with their brains.
It must seem odd that a blog about that usually discusses responsible environmental policy, interesting places, and beautiful organisms is posting an article that begins with a sentence like that. However, I’m a bit used to feeling odd at this point; I’m getting a degree in marine biology by studying neuroscience. Most of my friends are earning their degrees by going into the water with cages, nets, and jars, counting all the organisms they can find. Some lucky ones get to work in Fiji or Curacao. Meanwhile, I like to joke that the powers at be don’t allow me to go outside.
What is a neuroscientist doing in marine biology, and how does playing with a snail brain advance what we know about the oceans?
Simple behaviors, simple brain
To begin, the snail I’m referring to isn’t just a typical snail. The California sea hare, or Aplysia californica, seems more like a slug or a sea cucumber than a snail at first glance. Aplysia is gigantic, shell-less, and lives on the shallow California seafloor. When frightened or injured by predators, they release ink, much like a squid jettisons ink when it’s threatened. The ink, along with other chemical defenses which they store in their skin and gut, make Aplysia a rather poor dinner for a hungry predator, though they will get eaten by an occasional lobster or sea anemone. They live relatively peaceful lives overall, spending most of their day grazing for seaweeds and laying characteristic spaghetti-like eggs. Their behavioral repertoire is simple; they eat, they rest, they mate, and they escape predators.
By far, their most amazing attribute is their nervous system. On the most basic level, the nervous systems of all animals operate through the activity of neurons, single cells that communicate to each other using chemical or electrical signals. Amazingly, the function and role of our own neurons is identical to those of all other animals, including Aplysia. But while humans have around 86 billion neurons in our brains, equivalent to the population of the earth more than 7 times over, Aplysia has roughly the same number of neurons as the population of Havelock, NC, about 20,000. These cells are organized into little pockets of neurons, called ganglia, which share the same organization and structure from animal to animal. Best of all, Aplysia neurons are humongous, about the size of a letter on a penny and clearly visible with the naked eye. Their bright orange color makes them distinct from the tissues surrounding them and allows researchers to tell similar neurons apart.
Neuroscientists in the past have truly capitalized upon Aplysia to answer some very interesting and important questions. Because their neurons are so massive and their locations so uniform between animals, we have very detailed mental maps of the Aplysia nervous system. We know which cells synapse with other cells, what their roles in their respective neural networks are, and which networks correspond to specific behaviors that the animal exhibits. By monitoring and manipulating cells or circuits of cells, we can understand how behaviors persist through time, thus we can study how memories are formed and lost in a living and freely-behaving animal.
Like what you are reading?
Check back with us on Wednesday for part II when Kevin tells us why a marine snail is a huge part of memory and learning research!