Ramblings About Sea Urchins

April 6th, 2023
           
Hello! My name is Sammie Schreiter, and I am a participant on the NBP 23-03 cruise to Eastern Antarctica. The transit here has been great and novel for me. We got to clearly see constellations of stars and the southern lights! Never in my life have I ever thought I would see the northern lights, let alone the southern lights. We’ve also been seeing ice bergs and nothing could have prepared me for how blue they are. One of the primary investigators on this cruise, Sarah Gerken, told me that the reason why ice bergs are so blue is because the frozen water is so pure and the bubbles are squeezed out. Similar to why the sky and ocean are blue, the light that reflects back out from the bergs is also blue. It actually doesn’t feel as cold as I thought it would be, but that is probably because we get so bundled up so it can feel comfortable outside.
As of today, we have been to five stations collecting lots of important information about the environment at the bottom of the Southern Ocean. One tool in particular we use to collect invertebrates is called the Blake Trawl. We’ve seen an array of marine invertebrates including sea pigs, sea stars, brittle stars, marine worms, and sea cucumbers, sponges, and many more! One group that I’m interested in is sea urchins (also known as echinoderms).
           
​My master’s thesis research is about the genetics behind sea urchin embryo development. More specifically, I study what genes are turned on or off that allows a sea urchin embryo to grow. Even though I study a species found in the Atlantic Ocean called Lytechinus variegatus, I still am so mesmerized by the sea urchins I’ve seen here in the Southern Ocean. The starkest difference I’ve seen is the shape of the urchins. Lytechinus variegatus are circular, whereas many species here are closer to almond-shaped, like Pourtalesia hispida! I’m unsure of why they are shaped like that here, but I would love to know more about the genes involved in body morphology of these sea urchins and how that is different from Lytechinus variegatus. But one species, Sterechinus antarcticus, is also really cool because they are the same color as strawberry cake! I’ve never seen such a pink urchin before and that might be the best invertebrate I’ve seen.
 
Sammie Schreiter
Master’s Student
University of North Carolina Wilmington