Up Close with Urchins: Undergrads Collect Lab Specimens on the Gemma

This Earth Day, students at the Marine Biological Laboratory (MBL) took to the sea. 

Undergraduates from the MBL’s Semester in Biological Discovery (SBD) hopped aboard the MBL collecting vessel R/V Gemma on Tuesday morning to collect specimens for the SBD Embryology course. They were joined by course director and MBL Assistant Scientist Zak Swartz, whose lab at the MBL studies reproductive biology and development in sea stars. Sea urchins are also among Swartz's areas of expertise, and it was these that the crew hoped to collect for the Embryology course. 

“We’re trying to get more involved with the locally available biodiversity,” Swartz said, standing on the deck of Gemma. The goal was for the students to spawn the urchins in the lab, collect their sperm and eggs, and generate embryos, he explained. 

Captain David Bank took Gemma through the misty waters around Woods Hole and around Nobska Point. Bank and Scott Bennett of the Marine Resources Center used Gemma’s dredge to collect a bounty of organisms, including sea urchins, sea stars, horseshoe crabs, and comb jellies. 

Swartz and the students ended up taking roughly 50 urchins back to the MBL, but found it was too early in the season for them to be reproductive. The students instead generated embryos from a different species of urchin that was already in the lab.  

“The purpose of working with these animals in the lab was so that students could learn about fertilization: how sperm and egg find each other, especially in the open ocean; how sperm and egg recognize each other through molecular interactions, how the egg and sperm fuse, how the [fertilized] egg then prevents extra sperm from entering (very bad for development!), and then how the sperm and egg genomes combine,” Swartz wrote in an email the following day. 

As the eggs develop, the students are comparing the differences between sea urchin and sea star development, he added.