Sea Walnut
Mnemiopsis leidyi · Also known as: comb jelly, sea gooseberry (loosely), Mnemiopsis
Gelatinous comb jelly of Mid-Atlantic bays. Not a true jellyfish, and it doesn’t sting. Night lights can show its rainbow comb rows.
Quick facts
| Group | Comb jelly |
|---|---|
| Likelihood nearby | ★★★★☆ |
| Habitats | Coastal bays, Inlet, Ocean beach, Offshore / ocean |
| Seasons (this coast) | spring, summer, fall |
How to recognize them
- Oval, transparent body with eight comb rows that flash rainbow colors in moving light.
- Lobes at the front; no long stinging tentacles like scyphozoan jellies.
Biology notes
- Ctenophore that captures plankton with sticky cells (colloblasts), not nematocysts.
- Native to western Atlantic; famous invasive when introduced abroad.
Where to see them around Ocean City
- Calm coastal bay water and the Inlet after dark with a flashlight.
- Washed “blobs” on beaches that lack the horseshoe gonads of moon jellies.
When to look
- Warm months; bioluminescence and comb flashes best on dark nights.
Viewing tips & etiquette
- Safe to observe closely—no sting—but still handle gently if at all.
