LYNN – Christian, Julius and Amelia Serino?s eyes bulged and their jaws dropped Wednesday as an electric pump transformed a pile of rubber in the public library reading room into a 43-foot-long whale.The three quickly lined up to join other children for a chance to crawl into the whale?s belly for a mini-discussion on the massive mammoths with educator Cynde McInnis. For the Serinos, the “whale mobile” was their most recent opportunity to have fun while learning inside the Lynn library.?Everything they have done this year, the kids have really enjoyed,” said their mother, Jessica Serino of Lynn.The library wraps up its summer schedule with a City Hall ice cream social next Tuesday at 5 p.m., but the whale mobile?s visit capped off August library events and attracted 50 children and parents, aunts, grandparents and other adults.?I think it?s wonderful. It?s a free opportunity for children and you want kids to get familiar with nature,” said Lynn resident Tarsha Richards.Her son, Denzel Ancrum, looked forward since July to the whale?s visit.?He loves animals,” Richards said.McInnis explained to Ancrum and other children how whales are not just ocean giants glimpsed for a few seconds from a whale watch boat. She said scientists can identify individual whales by their tail markings and have tracked three generations of the beasts over a 30-year period, giving the whales names like “Polaris,” “Nile,” “Treasure” and “anchor.”?We see the same whales year after year off Massachusetts,” she said.Marilyn Martin of Lynn and her grandson, Aaron Eggeman, listened as McInnis detailed varieties of whales with teeth and “baleen” whales who filter small fish or other sea life into their mouths as they swim.?They spend about half their time eating,” she said.Whales also range thousands of miles, swimming from New England to the Caribbean, McInnis said. Their massive size does not make them invulnerable to human threats, most notably non-biodegradable nets and discarded plastic.Miriam Fusco of Lynn said the whale mobile with its kid-friendly interior was a summer library program highlight. Installing air conditioning in the cavernous reading room could enhance summer events, she said.?I think their programs are great. They are educational and fun. And they are free, which is a big plus,” Fusco said.