3 Types of Jellyfishes in Maine

1. What types of jellyfish are commonly found in Maine?

The most frequently seen jellyfish in Maine are the moon jelly (Aurelia aurita), lion's mane jelly (Cyanea capillata), and the sea nettle (Chrysaora quinquecirrha). Less common but notable are the comb jelly (Mnemiopsis leidyi) and the by-the-wind sailor (Velella velella). Moon jellies are translucent with four horseshoe-shaped gonads, while lion's mane jellies have a reddish-brown bell and long, trailing tentacles. Sea nettles are pale with a starburst pattern. Check out ouranimal hub for jellyfishfor more details on each species.

2. How can you identify jellyfish along the Maine coast?

Start with the bell shape and color. Moon jellies have a flat, saucer-like bell up to 12 inches, clear or slightly blueish. Lion's mane jellies have a domed bell covered in fine hairs, often reddish or orange, and can reach 3 feet across. Tentacles are the second clue: moon jellies have short, fine tentacles around the rim; lion's mane have long, flowing tentacles that trail far behind. Sea nettles have a bell with reddish stripes and stinging tentacles. Always keep a safe distance and never touch unfamiliar jellies. For a deeper dive, see ourMaine wildlife page.

3. Where are the best places to spot jellyfish in Maine?

Jellyfish are most often noticed from beaches and piers along the entire coast, but southern Maine beaches like Old Orchard Beach, Popham Beach, and the Wells Reserve are reliable spots. Rocky shores in Acadia National Park and the islands of Casco Bay also yield sightings. After storms, jellies may wash up on the strandline. Check local tide charts and wind conditions; onshore winds push them towards the beach. You can get more location tips on ourtypes of jellyfish in Maine page.

4. When is the best time of year to see jellyfish in Maine?

Peak jellyfish season runs from July through September when water temperatures reach their highest. Moon jellies show up first in early summer, followed by lion's mane in August and September. Sea nettles peak in late summer. Sightings drop off after October as water cools. For the best odds, plan beach visits during calm, warm days after a few days of southerly winds.

See ourstate animal guidefor the next step.

5. How do you tell apart lookalike species like moon jellies and lion's mane?

Moon jellies and lion's mane are often confused but have distinct differences. Moon jellies are nearly transparent with a shallow bell and four opaque white rings (gonads). They have a mild sting. Lion's mane jellies have a deep, orange-brown bell covered in fine hairlike structures, and their tentacles can stream 30 feet or more. Their sting is more painful. A good rule: if you see a jelly with long, wispy tentacles and a reddish hue, it's likely lion's mane. For a side-by-side comparison, browse ourjellyfish identification resources.

6. What should you do if you encounter a jellyfish while swimming?

If you see a jellyfish, avoid touching it and exit the water calmly. Most Maine jellyfish stings are mild, but lion's mane can cause moderate pain. If stung, rinse the area with vinegar (if available) or seawater, not fresh water, and remove remaining tentacles with tweezers. Apply heat or cold packs for pain. Seek medical attention if you have an allergic reaction. The best prevention is to shuffle your feet when wading in areas with jellies.

7. Where can you find resources to learn more about Maine's jellyfish?

Local marine labs like the Gulf of Maine Research Institute and the Bigelow Laboratory offer online species guides and sighting reports. TheMaine wildlife hubon Easy Street Markets also links to regional spotting advice. For a quick reference, ourjellyfish species chart T-shirtmakes a handy visual guide while you're out exploring.

Jellyfish Men's T-Shirt

A strong match for this wildlife page and an easy next click after the guide.Check Price and Availability

5Aup Scientifically Accurate Coral Reef Mug Gifts 11oz - Funny Tropical Fish, Jellyfish & Angelfish Design - Perfect Aquarist Ideal for Fish Keepers & Marine Biologists

A strong match for this wildlife page and an easy next click after the guide.Check Price and Availability

8. What gear can help you observe jellyfish safely and remember the experience?

A pair of polarized sunglasses cuts through glare and helps spot jellies near the surface. A waterproof camera or phone case lets you document finds. If you want to keep the memory close, consider ourJellyfish Men's T-Shirtfeaturing a detailed illustration. Or the5Aup Coral Reef Mugfor your morning coffee. For carrying gear to the beach, see ourwildlife tote bags.

Jellyfish Men's T-Shirt

A comfortable, durable tee with a realistic jellyfish graphic. Great for wearing on beach walks or casual outings.Check Price and Availability

5Aup Coral Reef Mug

This 11oz mug features a scientifically accurate coral reef design with jellyfish, angelfish, and tropical fish. Perfect for the marine biologist or fish keeper.Check Price and Availability

Jellyfish Species Chart T-Shirt

A detailed species chart printed on a shirt. Handy for quick field identification and starting conversations.Check Price and Availability

Feeling Jelly Jellyfish Graphic T-Shirt

A fun, whimsical shirt with a jellyfish pun. Lightweight and comfortable for warm days.Check Price and Availability

9. What is the moon jelly, and how do you recognize it in Maine?

The moon jelly (Aurelia aurita) is the type most people picture when they think of a jellyfish, and it is the most common one seen along the Maine coast. Its bell is flat and saucer shaped, clear to faintly blue or pink, and usually runs from a few inches to about a foot across. The signature mark is the set of four pale horseshoe or ring shapes near the center of the bell. Those are the gonads, and they are the fastest way to confirm a moon jelly from above.

Moon jellies have a fringe of short, fine tentacles around the rim of the bell rather than long trailing ones. They feed on plankton and tiny floating animals, which they trap in a layer of mucus on the bell and move toward the mouth. Their sting is mild and most people barely feel it, though touching one against your face, lips, or other sensitive skin can still cause a brief irritation, so it is best to look and not handle. You will often find them drifting in calm bays, harbors, and tidal flats, and they sometimes appear in large groups when currents and warm water concentrate them. For the broader species background, visit ourjellyfish animal hub.

10. What is the lion's mane jelly, and why is it the one to respect?

The lion's mane jelly (Cyanea capillata) is the largest jellyfish found in Maine and the cold waters of the Gulf of Maine are some of its favorite habitat. The bell is domed and ranges from yellow and orange to deep reddish brown, and on big individuals it can span well over a foot, with the largest northern specimens reaching several feet across. Beneath the bell hangs a dense, shaggy mass of fine tentacles that gives the animal its name, and those tentacles can stream many feet behind the bell, sometimes 30 feet or more on the biggest jellies.

This is the species to treat with care. The sting is the most painful of Maine's common jellies and can leave red welts and a burning feeling that lasts for a while. Loose tentacles in the water or pieces washed up on the sand can still sting after the jelly is dead, so give any reddish, hairy looking jelly a wide berth even if the bell is small. Lion's mane numbers tend to build through August and September, and they show up both in open water and washed along the strandline after rough weather. If you are wading or swimming, keep an eye on the surface and steer clear of long, wispy tentacle trails. For local context on where this species turns up, see ourMaine wildlife page.

11. Are comb jellies the same as true jellyfish?

No, comb jellies are not true jellyfish, even though they look similar and often get lumped in with them. Comb jellies belong to a separate group called ctenophores, while true jellyfish are cnidarians, the same broad family as sea anemones and corals. The most common one in the Gulf of Maine is the sea walnut (Mnemiopsis leidyi), a small, oval, transparent animal a couple of inches long.

The easy way to tell a comb jelly apart is to look for the eight rows of tiny beating hairs, called comb rows, that run down the body. In good light these rows scatter sunlight into a shimmering, rainbow ripple, and at night many comb jellies glow with a soft blue green bioluminescence when disturbed. The most important practical difference is that comb jellies do not sting. They have no stinging cells, so they are completely harmless to people and safe to look at closely if one drifts past. They feed on plankton and tiny larvae, and large swarms sometimes appear in late summer in warmer, calmer water. So if you scoop up a clear blob with shimmering bands and feel nothing, you have most likely found a comb jelly and not a jellyfish at all. Learn more on ourjellyfish animal hub.

12. Which Maine jellyfish sting and which are harmless?

Among the types you are likely to meet in Maine, the stingers and the harmless ones sort out clearly. The lion's mane jelly is the one to respect, with the strongest sting and tentacles that can reach far behind the bell, so it can reach you even if the body looks small. The moon jelly stings too, but the sting is mild and most people feel little or nothing unless it touches sensitive skin like the face. Sea nettles, when present, carry a sharper sting than moon jellies, though they are far more a mid-Atlantic species and are uncommon this far north.

On the harmless side, comb jellies have no stinging cells at all and are safe to observe up close. The by-the-wind sailor (Velella velella) is also essentially harmless to people; it is a small, oval, blue floating colony with a clear sail on top that the wind pushes ashore in drift lines. A simple field rule: long, hairy, reddish tentacles mean keep your distance, while a small shimmering blob with comb rows or a flat blue float with a sail is safe to look at. Either way, never touch with bare hands and rinse with seawater, not fresh water, if you do get stung. For tour planning around the season, see ourMaine wildlife pageandstate animal guide.