A Lion in the Sound

—Taro Ietaka, Director of Conservation and Land Stewardship

Participants in Rye Nature Center's new Paddle Adventure Camp will be looking for lions in Long Island Sound this year. Not the furry, growly kind - the slimy, red, tentacled kind: lion's mane jellyfish (Cyanea capillata).

Photo: Dan Hershman on commons.wikimedia.org

These brainless, spineless animals can become monsters in their arctic home, reaching lengths of over 100 feet, almost all of it composed of stinging tentacles. The bell (main body) of a full-size lion's mane jelly can be almost 8 feet wide. Luckily for swimmers and boaters in Rye, these creatures are locally rare, although sightings have increased in recent years. They also remain small in our area: on a recent training paddle in Mamaroneck, staff saw several lion's manes, but none were more than six inches across. Other jellyfish we may see include moon jellies (Aurelia aurita), comb jellies - small, transparent jellies who use sticky tentacles instead of stingers - and fresh water jellyfish (Craspedacusta sowerbii) that spread from lake to lake on the feet of waterfowl. 

Jellyfish numbers seem to be increasing globally as our oceans become stressed by temperature change, nutrient overload from fertilizer runoff, and other forms of pollution. Jellyfish behave in many ways like the invasive plants we are struggling with on land. Jellyfish are able to reproduce rapidly, have few predators, and can survive in degraded habitats including in low-oxygen dead zones. Like invasive species, they are also transported by humans. When they reach a new location, they are sometimes able to overwhelm the locals. The same moon jellies that act rather innocently in the Long Island Sound, have wreaked havoc in the Black Sea where they have gobbled up fish larvae and eggs, and bred in huge numbers. 

Jellies are amazing animals despite the problems that they can bring - stings to swimmers, fouled fishing nets, fish predation, and more. Their adaptability is admirable, as is their survival for tens of millions of years. Some jellies have partnered with algae to become floating algae farms, while another species may have figured out immortality - it breaks into independent pieces capable of regenerating instead of decomposing. So this summer, appreciate the jellies during your trips to the beach or aboard a boat - just do it from a distance.