How Northeastern scientists are using Antarctic sea spiders to study life on the edge
Northeastern students are helping a biologist extract spider guts — from legs as long as a dinner plate — to study how life survives in some of Earth’s coldest waters.
OAKLAND, Calif. — One of the best ways to learn how Antarctic sea spiders thrive under extreme conditions is to squeeze their guts out through their legs.
That’s what a Northeastern University biologist is doing to understand the otherworldly life cycle of marine arthropods that breathe, reproduce and digest through legs that can be as long as a small cat.
Assistant teaching professor Connie Phong wants to know how an animal adapted to live in a highly specialized environment — just below the freezing point for seawater — responds to warming oceans. And by warming Phong means a 10th of a degree.
“The first question is, how does life even survive at these very cold temperatures?” Phong says. “And then, what happens when it starts to get very warm?”
Animals used to a narrow range of temperatures, cold or hot, have a harder time adapting to even slight change, Phong says. By studying life “at the edge of what can possibly be,” she says, we get a glimpse of the biodiversity we stand to lose as the climate warms.
Gut microbes reveal a lot about an animal’s environment, including what it eats and what is in the water where it lives, Phong says. Sea spider bodies are very small, with eyes and a straw-like nose they use to eat. But the legs are segmented and long — sometimes long enough to make the animal as big as a dinner plate.
Working with spiders collected by Phong’s research collaborator, Amy Moran from the University of Hawaii, from ocean waters near the McMurdo Station, a research facility operated by the U.S. Antarctic Program, Phong is studying the earliest phases of life for sea spiders.
In most species, male spiders carry masses of fertilized eggs on their backs before dropping them off on shelves along the sea floor.
Life develops slowly at freezing temperatures, she says. For comparison, she says, it takes a fertilized frog egg an hour and a half to undergo its first cell division. For humans, it takes about 24 hours. For Antarctic sea spiders, a single cell division takes several days.
“When underlying enzymatic networks go so slow, at some point they can get stuck,” she says. “But life finds a way to keep on moving even in slow times.”
This summer, while teaching an undergraduate biology project lab course on the Oakland campus, Phong worked with students to study microbes from sea spider guts, which are housed in the spider’s legs with all other vital organs.
Specimens like the ones Phong has are hard to come by. She only had two or three legs from three different species. So Phong and her students talked a long time about the best way to get the guts out.
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“They cracked open these legs, which have an exoskeleton that they needed to separate from the actual mushy parts of the guts,” she says. “They were careful. They kept the guts separate between the segments so they didn’t cross-contaminate the samples.”
Spider guts look like “the inside of a banana peel,” says Alexandra Barnes, a sophomore biology major who took Phong’s course this summer. After carefully extracting DNA from the guts, the students attempted to clone bacterial genes out of the community DNA sample. Students verified their cloning products by DNA electrophoresis, applying current to a sample to see if they migrate at the expected sizes, she says.
Through this process, students were able to isolate “cold shock proteins,” which animals produce to cope with cold temperatures and other stresses. Further sequencing of the samples they extracted may answer questions about how the spiders survive and how they are adapting to warming waters.
“With spiders that are always living in the cold, there might be some differences in that protein,” says Mariella Fayad, a junior biology and political science major who also took the course. Sequencing results will help researchers “understand the difference between Antarctic sea spiders versus cold shock proteins in other animals,” she said.
Because they live in freezing conditions, the spiders aren’t easy to study, says Phong. But Barnes and Fayad were successful at obtaining gut microbes that may provide insights into the spiders’ physiology and interactions with their native environments.
“I’m proud of the work that they were able to do,” Phong says. “It is really novel research.”
Phong may present the work at the next meeting of the Scientific Committee on Antarctic Research in Oslo, in which case Fayad and Barnes would be invited to attend.
“This is research that I will continue to work on, but I’m really glad to be able to use it to teach students,” she says. “A lot of the work we did together, like the cloning out of these genes and thinking about DNA in a community, they have all of these as abstract concepts from classes, and then they get to apply it in research and that is very powerful.”
