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CRITTER SPOTLIGHT: Comb Jellies: Mnemiopsis leidyi

Good Morning Awesome Watershed Explorers,


I hope that you enjoyed the beautiful weather this week and got outside. This week is going to be more seasonal for spring, a bit colder with some rainy days. These are the perfect days for our amphibian friends! I know our backyard retention pond could use some water. We miss the peep peeps and the garbles of spring peepers and wood frogs. This is a great reason to throw on a raincoat and rain boots and get outside for some amphibian exploration.


I owe the idea for this week's critter spotlight to my wonderful friend Kim Heon from Agnes Little in Pawtucket. Mrs. Heon was walking with her husband at Scarborough Beach and thought she came across some jellyfish. Mrs. Heon did some research and identified the critters as comb jellies, Mnemiopsis leidyi. These critters which are known as ctenophores look very much like jellyfish but they are actually in their own distinct group. One very important difference is that ctenophores do not have stinging cells. Most comb jellies also don't possess tentacles and when they do, the tentacles come from their center. Here is a photo of comb jellies.

Comb jellies eat zooplankton and sometimes larval fish. This can be a significant problem in saltwater ecosystems. It has been a problem in Narragansett Bay in recent years. Due to slowly rising water temperatures, comb jellies are present in the water earlier in the spring and stay later into the fall which has harmed fish populations. The other reason why comb jellies are troublesome is that they are not nutritious nor delicious and therefore are not eaten by many other animals. Ctenophores don't eat or reproduce until water temperatures reach 50 degrees Fahrenheit that is why warmer water temperatures positively impact their populations and negatively impact the populations of native fish.


An interesting connection to the Narragansett Bay Commission's wastewater treatment facilities is that it is thought by scientists that due to the decreased levels of nutrients, especially nitrogen, coming from the effluent discharged by the treatment facility that less food is available for phytoplankton. Phytoplankton are food for zooplankton. This food chain connection means that if there is less food for phytoplankton, there is less food for zooplankton and therefore less food for comb jellies. Scientists agree that these changes are not catastrophic, but they are changes that need to be observed. This is why the scientists at the University of Rhode Island's Graduate School of Oceanography are keeping a close watch on Mnemiopsis leidyi. For more information on comb jellies in Narragansett Bay, check out this article where Mrs. Morissette gathered a lot of her information https://www.ecori.org/natural-resources/2020/9/6/warmer-narragansett-bay-causes-seasonal-shift-in-jellyfish-like-creature


A very special thank you to Mrs. Heon once again for this great critter spotlight idea. I would also like to publicly thank Mrs. Heon for her continued support of the Watershed Explorer program. Her students showcased some of their critter project work this week and they are all doing a fantastic job. I hope to post some pictures of their work soon.


I wanted to leave you all with two quick videos from our adventures this week in the Wood-Pawcatuck Watershed. We found some amazing creatures to present to Mrs. Heon's class during their macroinvertebrate lesson this past Thursday.




Happy Exploring Friends,

Mrs. Morissette


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