The Answer to This Mystery? Ghosts.

When the National Aquarium team performs routine maintenance of our floating wetland prototype in the channel between the Aquarium buildings on Piers 3 and 4, they sometimes use a submersible camera to see the structure's underbelly. Recently when they were doing this, they saw several small, pale organisms attached to the wetland's underwater walls and support structures. As they widened their search, they found more on the air-filled pontoons that keep the wetland afloat, and still more on the pier pilings nearby.

National Aquarium General Curator Jack Cover and Director of Field Conservation Charmaine Dahlenburg worked with research partners at the Institute of Marine and Environmental Technology to use DNA analysis and genetic barcoding to confirm that they were seeing exactly what they had suspected: the eerily named ghost anemone.

Sea anemones, which can look like exotic, pulsating flowers adorning tidal pools and reefs, show their greatest diversity in warm tropical waters, but these amazing animals can be found across the globe, in all marine habitats—including right here in Baltimore's Inner Harbor.

Ghost anemones are one of the few species of sea anemone native to the Chesapeake Bay, where they are abundant and widespread. While all anemones look like flowers—which is where the name "anemone" comes from—they are actually invertebrates related to corals and jellies.

Able to survive in brackish and low salinity waters, ghost anemones live on rocks, oyster reefs, pilings, submerged logs and branches, and other hard surfaces throughout the Bay. Even though they are always attached to a hard surface, they can move relatively quickly—up to several inches in just a few hours.

They're small—about an inch-and-a-half tall and a half-inch wide—and somewhat transparent, usually with a white or pink tint, although some can appear more green or brown, thanks to tiny algae growing within their bodies and tentacles.

They have a flat, rounded base and an elongated stalk, almost like a mushroom, except where a mushroom's cap would be, they have about 50 wispy, petal-like tentacles encircling a small mouth.

Anemones are carnivores, feeding on plankton and tiny fish. Their stinging tentacles are triggered by the slightest touch, firing a harpoon-like filament—called a nematocyst—into their prey. After the anemone injects the paralyzing neurotoxin, it guides its prey into its mouth using its tentacles.

The dense number of ghost anemones near the aerators on the Aquarium's floating wetland prototype is likely due to the abundance of food they find in these locations. The continuously moving water, created by the aerators' rising bubbles, provides a constant supply of plankton.

Despite anemones' ability to sting and stun, some animals can make a meal of them. Many species of fishes feed on anemones, as do sea stars and snails.