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Jellies, jellies everywhere

Published August 20, 2009

If you have been to the beach or out on a boat recently you have probably encountered a jelly or two, perhaps even more. This is the time of year that jellies are most prevalent in the mid-atlantic region. So why do we see so many of them during the summer?? Jellies are found in most bodies of water, including the Atlantic Ocean, the Chesapeake Bay, and even in Baltimore’s Inner Harbor. In fact, some Aquarium employees saw a bunch of comb jellies in the harbor earlier this morning.  In this region, most jellies are seasonal. The greatest variety of jellies are found in the lower bay, in the coastal bays and, offshore in the Atlantic Ocean were salinities are higher. Some of the more common species include:jelly on beach small
  • Moon Jellies, (pictured to the right) found in the Lower Bay and Atlantic Ocean. In the summer months the remains of moon jellies can often be found washed up on the beaches, but they rarely sting people.
  • Atlantic Sea Nettles, found in the middle and lower bay and seen in late spring, summer and early fall and the most likely to sting you. They sting thousands of beach-goers each season!
  • Comb Jellies, found throughout the bay and ocean year-round but most commonly seen in the warmer months. Comb jellies do not have the ability to sting.
  • Lion’s Mane Jellies, found in the bay from late November through May, also known as the winter jelly and also deliver a powerful sting.
Local jelly populations fluctuate greatly from year to year, but species like the Atlantic sea nettle are naturally very abundant by mid-summer in the Chesapeake Bay. Long-term increases in local jelly populations or a lengthening of the jelly season could be the result of environmental degradation caused by human activities. As our exhibit points out, jellies are survivors. Jellies have survived for over 500 million years. They have survived environmental changes that have negatively affected other forms of sea life. The key to this survival is their ability to adapt and thrive to changes in the environment. Jellies appear to be better able to survive in polluted water than other forms of aquatic life. Polluted runoff from the land makes life impossible for many aquatic species, except for jellies. Fertilizer, manure, and sewage runoff into streams and the ocean decreases oxygen levels, leaving water hypoxic and unable to support many forms of aquatic life. When water conditions are poor, fish find it hard to breathe so they go elsewhere or die in large fish kills. But jellies have very low oxygen requirements and are able to survive, and even thrive, in these human created conditions. In addition, many seasonal jellies appear and reproduce when the ocean warms up. Global warming is making the ocean temperature warmer thus extending the growing, feeding, and breeding season of several jelly species. Some jellies also appear to be adapting and expanding their ranges due to this warming climate. Warmer water also speeds up the jellies' metabolism, causing them to consume more food, grow, and reproduce faster. So next time you are in the water a spot a jelly, think about how human actions on land may be helping jellies multiple, and increasing your chances of receiving an annoying summer time sting!
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