Project Background

What am I doing?

The aim of this project is to explore how and why a species might switch from one development mode to another, using the sea slug species Elysia crispata. I picked this species because they are commercially available with a variety of food sources that are easily cultured. They are also a member of the only genus that has 3 plastic species, and is very closely related to one of them. While this species has not been confirmed to be plastic, I aim to see if they can be pushed to become plastic by manipulating their environment.

How did I get here? 

This project is my Undergrad capstone project and background research officially began in the fall of 2024, but it has been in the works for much longer.  I started out at Daemen in the fall of 2022 as a nursing major, and quickly discovered it was not right for me. I decided to switch my major to Biology since I had always done well in biology classes and it would allow me a lot more flexibility as I learned what I did and didn't like since it is such a wide field. Friends of mine had warned me about the struggles in chemistry classes, so I decided to take an upper-level science class since that seemed like a less daunting way to get enough credits to remain full-time. 

That's how I ended up in Dr. D'Amore's herpetology class, and I truly loved that class. A lot of the information we learned just clicked and I finally felt like I was doing what was right for me. When I switched my major, I was told that there would be a big scary research project that I would spend half of my college career working on, so I made sure to keep my eyes peeled for ideas. So when I was sitting in that herpetology class and we learned about a species that was unique in its development, I wanted to know more. So much more that I decided then and there that I would research the fire salamander, Salamandra salamandra for my big scary research project. 

Unfortunately, fire salamanders were not going to be suitable for this since we cannot catch them wild here, they are a protected species in their native area. There were also concerns about being able to keep them alive and happy enough to reproduce. This species has subspecies that undergo indirect or direct development but are fixed within a subspecies, meaning we would likely have to cross individuals from different subspecies, which would take years.

When it was clear we were not going to be able to work with salamanders, I looked to see what species showed plastic development and found the aquatic snail species Planaxis sulcatus, which was said to show plastic development. There were issues with getting them since live specimens are not sold commercially, and they are not native to where we live, so we would not be able to catch them. It was also later discovered that they do not show plastic development and instead are two very similar, related species of snail. So the search began once again to find a species. 

While reading papers about plastic development, one of them mentioned that plastic development was quite common in nudibranchs. So I decided to spend an entire day searching through all ~3500 species of nudibranchs to see which species showed plastic development and were either commercially available or native to the United States (excluding Hawaii and Alaska). Of those roughly 3500 species, four of them fit those criteria. 

Of those four, the species Alderia willowi was my first choice since every population of this species has been shown to have plastic development, and no papers disagreed. So I reached out to the professor at California State University who discovered this species to try to gather information on how to get them and work with them. It quickly became clear that this species would also not be a suitable option since they are not available commercially, and the process to get permits to collect them takes a minimum of five months. Coupled with the fact that their food source is also not native here, and is difficult to culture in a lab setting, we had to explore one of the other four. 

This is how we landed on two species of Berghia. Some populations of Berghia verruiciornis show plastic development and have been linked with egg aeration, which is a variable we could test. They are commercially available through aquarium stores for the purpose of controlling outbreaks of aptasia coral. This is great for us since it means that their food should be easy to culture, and we do not have to wait for permits to start our research. 

Between their fast reproduction rate and their easily cultured food source, aptasia coral, this pair of species would have made an excellent model pair. Unfortunately, confusion in the literature means that online shops selling nudibranchs don't know which species they carry. It turns out the place I wanted to buy B. verrucicornis from actually sells B. stephanieae and lists the incorrect species name and picture. No one, anywhere, has this plastic species. And unfortunately, the process to get authorized to go out and catch them in the wild would take longer than we have for this project. This means we must switch species yet again. This time, I decided to pivot to a commercially available species of sea slug, Elysia crispata. 

The genus Elysia is the only genus of nudibranch or sea slugs that has 3 confirmed plastic species: E. chlorotica, E. Zuleicae, and E. pusilla. All of these species follow cues from their host algae to determine the developmental mode of their offspring. E. crispata has not been documented to show this plasticity, but I aim to see if this species can become plastic under the right conditions. They are very closely related to E. chlorotica, so it is possible they have the underlying genetics to become plastic. This species also eats a wide variety of macroalgae, most of which are hearty and fast-growing, which bodes well for long-term culturing.