Norwich - Members of the Norwich Sunrise Rotary returned to the Norwich Free Academy Friday morning joking about missed detentions or overdue homework, but the classroom they visited certainly wasn't in their lesson plans.

The group recently donated $850 to the rapidly growing marine sciences program, and teacher Seth Yarish invited members to visit the classroom and watch students in action with the collection of critters that now reside in the lab.

Seniors Breanna Salter of Voluntown and Andrew Kinney of Norwich hauled one jittery lobster out of a tank for closer observation in a small plastic bin and put several tiny Pacific shore crabs in a second bin.

Students caught the crabs off Bluff Point during a Project Oceanology trip. Norwich ShopRite supermarket donates lobsters to the lab. The sharp decline in local lobster population makes it hard to obtain lobsters, Yarish said. Students are studying possible causes for the decline, with no answers yet.

Rotary member Beth Troeger reached into the bin and picked up a Pacific shore crab - about the size of a half-dollar coin. She let the creature crawl along her hand and wrist.

Yarish said the Pacific shore crabs, also called Asian shore crabs, probably were transported to Long Island in the bilge of ships. They do not seem to be "invasive" or harmful to native species.

Kinney picked up a chunk of squid with tongs and brought it to a 55-gallon tank that holds a sea bass and a spotted hake. One of the fish made quick work of the squid.

Most of the tanks in the lab can hold 45 to 55 gallons of water. The lab's centerpiece is a giant round 450-gallon blue plastic tank, partially funded by Norwich Public Utilities. Yarish said the new tank he hopes to buy will allow more visibility of the fish.

NFA students take Project Oceanology trips to study Long Island Sound and the Thames River, collecting specimens. They bring salt water back to the lab in big jugs.

"Or we make it," Kinney said, pointing to two large sacks leaning against the classroom wall. "Instant Ocean Sea Salt," their labels read.

Students learn about the species' behaviors and protective characteristics. Students also have to feed and monitor the fish, clean the tanks, check water temperature and make sure filters are running. During the summer and school vacations, Yarish cares for the fish.

The lab is proud of one fish, a gray trigger fish normally found in southern Atlantic coastal waters. The aggressive, sharp-toothed fish ride the Gulf Stream to New England in warm weather, and NFA students caught one in 2013. A student brought its tank home and took care of it last summer, Yarish said.

Rotary members admired a much smaller specimen, a perfectly camouflaged oyster toadfish that remained hidden in a small rocky cave. "It looks just like a rock," someone said.

Three NFA science teachers work in the marine sciences program. In addition to Yarish's Long Island Sound studies, Ryan Czaja, who joined the school from Mystic Aquarium, runs a tropical and coral reef classroom. And Heather Botelle teaches advanced biology, environmental science and natural resources.

Kinney and Salter are earning University of Connecticut college credit in the advanced class. Junior Meghan Cook of Voluntown said she wants to study nursing, but already volunteers at Mystic Aquarium using her experience in the NFA program.

"The marine science program here is amazing," she said.

c.bessette@theday.com

Twitter: @Bessettetheday