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The phosphorescence is here!

Gelatinous greenish blue glowing globs of no-brain jellyfish are lighting up the shallows of Nantucket Sound and the harbors right now, but you’ll have to venture out at night to see them.

Fireflies of the sea, the much-ballyhooed so-called phosphorescence are the natural neon that swarms in the inland waters of Nantucket for those who love nocturnal marine adventures this time of year.
Can’t sleep because of the humidity? All hot and sweaty from clubbing or dancing at the Box? Get out to the harbor or the North Shore for a liquid laser lightshow that the fog can’t stop.

Not an electric form of microscopic plankton as many islanders and seasonal visitors believe, and continue to tell others of, the bioluminescence seen near shore from mid-August are actually clear, walnut- to lemon-size jellyfish called Leidy’s comb jelly that are classified as a plankton and have no brains. When agitated in the water, these non-stinging jellyfish that appear nearly clear and almost invisible during daylight hours, produce green-blue chemical light through a bioluminescent process along eight rows of combs tightly lined with cilia (tiny hairs) that pulse in concert with each other to move the jellyfish through the water and suck in food.

The bioluminescence is created by a chemical reaction produced by the interaction of the organic molecule luciferin and the enzyme luciferase similar to that of fireflies.
But you shouldn’t confound yourself with the biology of this simple invertebrate, though you may want to hold them in your hands or close to the surface of the water to see their cilia vibrating in unison, you should get out and see these spectacular underwater shooting stars while they’re here. I like Polpis Harbor in one of my kayaks on a calm, clear and cool evening when most of the boats are moored so I can have the harbor and just outside of it all to myself. I prefer my sit-on-top to the sea kayak that I usually paddle in because it’s nice to be able to get out on a sand bar or beach and splash around in the water to get the comb jellies to do their thing.

You can start your paddle whenever you choose, but the jellyfish with flashlights won’t be visible until it’s almost completely dark.
Polpis Harbor is found at the water end of two access points. The first, labeled Polpis Harbor Road, is on the north side of Polpis Road just before its intersection with Wauwinet Road and the second is on the north side of Wauwinet Road opposite 19 Wauwinet Road.

You needn’t leave the confines of Polpis Harbor to see thousands of nature’s brightest lights, but then kayaking isn’t for everybody, which is why Steps Beach is the perfect wading place for seeing the “phosphorescence” on Nantucket. Get there from town by finding Lincoln Avenue by going down to end of North Beach Street, going left onto Jefferson Avenue and then left up Cobblestone Hill. At the top of this cobblestone road, go right and at the west end of Lincoln Avenue; look for public way down toward Nantucket Sound and the stairs beyond that lead down to the beach.
Bolt down the 41 steps leading to Steps Beach from the top of the Cliff at the west end of Lincoln Avenue and find a patch of sand at the bottom for your towel and remember when you put it because it will get dark. Like kayaking through Polpis Harbor, you don’t want any light other than moon, stars and lights from the houses on the Cliff. That glare alone could spoil your phosphorescence experience.

I like to find a good stretch of shallow, even shoreline on a warm night and walk along calf- to knee-deep in the water stirring up the jellies and watching them turn on and turn off. Try it underwater as well. Since there is no sting, there is nothing to fear.

The Leidy’s comb jellies are swarming all around the island right now through the middle of September, so you’ve got plenty of time to get out there and see the lights.