It's alive!

A hydromedusa (top), cerinula larva (middle),
and claim (bottom). Photos by Declan Lane.

Recently, two of my high school interns asked for a lesson. We have been working for months on sorting plankton from the Arctic, but all these samples are preserved in ethanol. They don't move. They just hang there in the liquid, begging to be sorted. My interns wondered what it was like to sort live plankton instead. 

Of course I was happy to show them. We grabbed a plankton net from my lab, dragged it through the water off the dock in Eel Pond, and looked at the sample together under the microscopes. It is so satisfying for me to introduce new students to science - I love guiding their curiosity, listening to their exclamations, and showing them the incredible diversity in the ocean. 

The sample we collected happened to be full of medusae. If you've heard the word "medusa" before, it was probably in context of Greek mythology, but the woman with snakes for hair is not what I'm talking about. In marine biology, "medusa" refers to the bell-shaped life stage of jellies and hydroids. If you picture a stereotypical jellyfish, that's a medusa - round, bell-like, lots of tentacles. True jellies spend most of their life in the medusa stage, but hydroids also have a medusa in their life cycle. Since it's spring, plenty of hydroids are reproducing right now and sending their medusae into the water column. I ended up mapping out true jelly and hydromedusa life cycles on the white board to show the interns (I couldn't help myself). 

Soon after the medusae, the interns started noticing larval anemones and worms in their dishes. The star of the day might have been a clam, though. It was crawling through the dish with its foot, probably a newly-metamorphosed juvenile that had gotten knocked off the dock to end up in our net. The guys couldn't resist filming it through the microscope. 

Invertebrates are absolutely fascinating, and I love introducing new students to the diverse marine animals that I love. It was a great afternoon.