Week 2 is in the books! I’ve learned a lot in the lab in these past two weeks and have also enjoyed getting to know the other interns and hearing all about their projects. Last Saturday, we went out on the R/V Pluteus to do some dredging. Lots of fun, lots of waves, a little bit of motion sickness – but all in all an amazing day! We found a ton of cool stuff: basket stars, a variety of sea cucumbers, soft-body corals… On Sunday, Chris, Nancy, and I went on a short hike at Sunset Bay and Shore Acres State Park. It was absolutely beautiful and we couldn’t help but stop every few minutes to take pictures of the breathtaking views. We also had a professional development session this week in which we talked about research/science ethics and gave short presentations of our project proposals. Mia (Richard’s fabulous chihuahua) was a fantastic listener (see below).
We spent most of last week learning the basic techniques we’ll need to do our experiments. This week, we started jumping into our project! Kostantina and I, with lots of help from our mentor George, will be investigating adaptations of ciliated larvae for prey capture. Before a sea urchin or star fish or sand dollar can be a sea urchin or star fish or sand dollar, it needs to grow up from a tiny embryo! Between the moment an egg is first fertilized by sperm and the juvenile phase, these invertebrates must go through a larval stage. During this time, these organisms look entirely different from their future adult forms. Looking at larvae under a microscope is like looking at clouds – some look like spaceships, some like giraffes, some like astronauts… Anyways, these larvae all have something in common – they use cilia (short, hairlike projections on the surface of certain cells) to swim and eat. These cilia can be found in the form of a ciliary band, which allows larvae to create currents to transport particles of food into their mouths. Invertebrate larvae, like humans, seem to have some foods they prefer and some that they’d rather avoid. One example of this is the nemertean pilidium larva, which appears to be incredibly efficient at capturing a type of algae called cryptomonads. Cryptomonads are a particularly good source of food: they are naked, nutrient-rich, easily-digestible cells. There is one caveat, though: cryptomonads have an escape response in which they essentially shoot out a microscopic thread that allows them to rapidly jump – a useful tool when trying to escape from a predator’s mouth. However, the pilidium larva is quite successful in eating these algae, and it does so by essentially not providing any indication to the prey that it’s being eaten until it’s too late! Before they know it, the cryptomonads are trapped in the pilidium’s large and deep mouth with no means of escape.
We are interested in understanding whether big, vestibular mouths help ciliated invertebrate larvae capture cryptomonad prey. We will be manipulating embryos of sand dollars, sea urchins, and star fish in order to create larvae of different sizes and size ratios and thus various mouth sizes. High-speed video will be used to determine whether it’s easier for prey to escape from small mouths, and confocal microscopy will be used to understand the impacts of our manipulations on larval proportions and the ciliary band. This week, we started a few cultures of half- and quarter-size sand dollar larvae, and we’ve been documenting their development using a compound microscope. In later weeks, I’ll get more into the nitty-gritty of the techniques we’re using! Thanks for reading!
Hello! My name is Ana and I am a rising senior studying biology and music at the College of the Holy Cross in Worcester, Massachusetts. This summer, I am working under the mentorship of George von Dassow. I am looking forward to seeing where my research takes me and to becoming a part of the OIMB community!