The Atlantic nettle is one of the best-known jellyfish on the east coast of the United States, especially in the Chesapeake Bay and Rehoboth Bay, where it commonly stings swimmers. Since it was described nearly 175 years ago, they have been assumed to be a single species. Up to now.
The discovery that they were actually two different species was made possible by DNA sequencing techniques.
“Before DNA, we looked at organisms and classified organisms by their physical characteristics to identify species,” according to Patrick Gaffney, one of the study’s authors.
“In the case of this jellyfish, which has been known for centuries, it was discovered through DNA sequencing that there were actually two groups .”
It turns out that the ocean-based sea nettle jellyfish is larger and has about 40 percent more tentacles (40, compared to 24) than its seashore counterpart.
Differences in DNA
The sea nettle also has a bell, the upper part of the aquatic animal, larger, while the tentacles are shorter than those of the bay nettle species.
Genetic testing of samples revealed differences in some of the marine nettle jellyfish : it was confirmed that there were actually two distinct species: an oceanic species ( Chrysaora quinquecirrha , or sea nettle) and a bay species ( Chrysaora chesapeakei , or bay nettle). ) by comparing DNA data from physical measurements of each species.
“When you pay close attention, you start counting the number of cells and types of burning, and you see slight differences that correspond to the DNA, ” according to Gaffney. “In many cases, when we plotted the data, the graphs looked completely different without overlap, reaffirming that they are two species.”
The recently recognized species is nettle, found in less salty waters called estuaries, such as the Chesapeake Bay. The National Oceanic and Atmospheric Administration (NOAA) produces a daily jellyfish forecast for the Chesapeake Bay, where jellyfish blooms can sometimes become a nuisance.
According to Gaffney, having two distinct species may explain why efforts to understand the factors that affect jellyfish bloom are so difficult.
The discovery may also be good news for the eastern oyster, which is found off the Atlantic and Gulf coasts and is the most widely consumed type of oyster.
This is because berry nettle jellyfish eat harmless comb jellies called Mnemiopsis, a key predator of oyster larvae. If bay nettles are effective at harvesting Mnemiopsis , the larvae of the eastern oyster may have a better chance of survival.
Interestingly, the new research showed that nettle appears to be closely related to jellyfish found in the coastal regions of Ireland, Argentina, and Africa . But according to the researchers, it is not unusual for no one to have noticed these differences before.
According to scientists, jellyfish are something that people do not pay attention to because they are fleeting. They come and go, they are difficult to study and do not have hard parts like shells that wash on the shore.
The research has been done in conjunction with the University of Delaware and the Smithsonian’s National Museum of Natural History.
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