Marine educator Mike Dunn and Dennis Hansen of the Penobscot Marine Museum set up a 100-gallon tank filled with rocks, sand, water and sea creatures from Penobscot Bay in the central hallway of the Captain Albert Stevens School in Belfast last week, where it will remain for a period of two months.

As they shoveled sand into the empty plexiglass box, students looked on in curious anticipation at what they termed the “touch tank.”

Dunn, who runs a one-man business called Marine Education Experience Unlimited, prefers “lobster ecology tank,” and said the aquarium’s namesake, a two-and-a-half-pound, unbanded lobster named Iron Claw, meant there wouldn’t be a lot of unsupervised touching.

The purpose of the tank, which is on loan from the Penobscot Marine Museum, is to show students what life is like just beyond the beach.

“It’s not like a lobster tank you see at Shop ‘n Save, because it will have more than just lobsters in it,” Dunn said.

Incorporating “live sand” — sediment containing microbes, bacteria and small plant and animal life — bay water, and an assortment of filter feeders, grazers and carnivores (barnacles, sandworms, clams, brittle stars, dogwinkles and periwinkles, hermit crabs, green crabs, rock crabs and numerous smaller things), the lobster ecology tank is essentially a slice of the sea floor.

For the most part the tank is self-sustaining. The crabs eat the lobster’s leftovers. The sea stars go after the barnacles. Anemones, periwinkles and starfish are all likely to reproduce, and so on.

Without the circulation of the massive amounts of water that would normally be present in the bay, the tank requires filtration and the transfer of around 15 gallons a week to add microorganisms. The water is also kept at a constant temperature of 56 degrees Fahrenheit.

Otherwise, most of the animals can survive on what is already in the tank, Dunn said. Iron Claw is the exception, needing around two pounds of clams and mussels per week, to be added by the tank attendant.

The tank has done residencies at the Searsport and Stockton Springs elementary schools, and Dunn said students’ interest follows a predictable pattern. The tank draws a lot of interest at first, then the novelty wears off. After several weeks they start looking again, and it’s at this point, Dunn said, that they begin to notice the subtle changes that characterize the ecosystem.

“They’ll get to see crabs shed,” he said. “Maybe they’ll get to see something eat something else.”

Whatever the school does as far as building curriculum around the tank is up to the teachers and staff, Dunn said. What he hopes is that when the two months are up, the students will be a little more aware of things they can see for themselves in the shallow waters of the bay.