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Billie Swalla

Research areas

Billie Swalla’s research is focused on a complex, interdisciplinary biological question. When and how did chordates evolve? Her research suggests that our earliest ancestors were worms, living in the mud and eating plankton and detritus. These worms also filtered water for plankton and probably also for oxygen. The closest living representatives of these ancestors are hemichordates, marine worms that are related to the better known echinoderms, such as sea stars and sea urchins. Echinoderms and hemichordate worms have similar embryonic development and become ciliated larvae, which float and feed in the plankton. However, after metamorphosis, echinoderms have a hard, spiny endoskeleton and are bottom dwellers, while the soft-bodied hemichordates burrow into the marine sand or mud. Her research compares the genes and genomes of these invertebrates, which are related to us. We look at similarities as a way of telling which groups are related to the other groups, and examine the expression of homologous genes in order to see how genes may be used in a similar way, or co-opted for different functions. These questions do have relevance for human health and development because echinoderms and hemichordates are able to do remarkable adult regeneration.

Marine Biology Courses

Comparative Invertebrate Embryology (FHL summer course)

Comparative Invertebrate Embryology will use hands-on lab experience to introduce students to the great diversity of developmental modes and processes found among marine invertebrates. The course will bridge cell and molecular approaches with ecological and evolutionary approaches to provide an integrated view of animal development. The course is intended to serve both biologists who wish to understand diversity in modes of development for ecological and evolutionary studies, and cell and developmental biologists who wish to broaden their knowledge of embryos beyond the standard model systems.

In her own words

Why is your area of research interesting? Relevant?

My research investigates what genes are important during embryonic development and regeneration in invertebrates. Humans have these same genes and mutations in them cause cancer and aging. If we know what controls regeneration, then we may be able to stimulate humans to regenerate lost or damaged tissues.

What is your favorite marine species, habitat, or process you’ve studied so far, and why?

I love hemichordates. They are related to echinoderms, but instead of having radial symmetry, they have bilateral symmetry, like humans. There is very little known about them and I began studying them in 1997, because I think they look the most like the vertebrate ancestor.