Actress Mayim Bialik, in Philly, marks anniversary of the bat mitzvah

In Hebrew, her name means "water," and that became the theme of her bat mitzvah.

The color scheme of her party was ocean blue. Live goldfish stared from glass bowls on tables. And for the guests, submarine sandwiches.

She was the first woman in her family to celebrate a bat mitzvah. Nearly 25 years later, the intensity of the religious covenant she undertook that day has only deepened.

"I loved it," actress Mayim Bialik said in an interview. "I don't know that it even occurred to me that girls don't usually do this."

Bialik, 36, is widely known as Blossom, the TV character she portrayed on the 1990s sitcom of the same name. She played a young Bette Midler in the movie Beaches, and now portrays neurobiologist Amy Farrah Fowler on The Big Bang Theory.

On Sunday, Bialik spoke at the National Museum of American Jewish History to mark the 90th anniversary of the bat mitzvah, a ceremony that seems ancient but that actually represents a new and profound idea - that girls would be treated the same as boys.

Questions flew from the audience:

How did she manage to prepare for her bat mitzvah - Beaches came out the same week - amid the demands of acting?

"I was just a giant nerd," Bialik answered to laughter. She was devout, fascinated, and immersed in her Judaism, so she studied hard.

What is it like to be observant in Hollywood?

"Complicated," she said. "Difficult." The industry focuses on what's outside, and she focuses on what's inside.

What advice does she have for girls?

"The bat mitzvah is the beginning," she said. "It's not the end."

Nearly 200 people filled the museum's Dell Theater to hear Bialik talk, part of a series of programs recognizing the anniversary.

The first bat mitzvah took place in New York on a Saturday morning in 1922, when Rabbi Mordecai Kaplan called his 12-year-old daughter, Judith, to the front of the synagogue. It was revolutionary - women had gotten the right to vote only two years earlier - yet quickly became widespread in American Judaism.

Today what was once an unusual, controversial idea has become a core element of the faith.

To celebrate the anniversary, the museum joined with Moving Traditions, a Jenkintown education group, to organize an exhibition. "Bat Mitzvah Comes of Age" continues through April 27 at the Jewish Community Center in New York City, then travels to communities throughout North America.

"In conducting research for the exhibition, we heard from women who were willing to raise their voices and challenge the gender expectations of their time," Moving Traditions' executive director, Deborah Meyer, said in a statement. "These 'bat mitzvah pioneers' moved girls and women from the margins to the center of Jewish life."

Girls generally reach religious maturation at 12 years and a day, boys at 13 and a day. The milestone known as bat or bar mitzvah means "daughter or son of the commandment." Bar mitzvahs for boys have existed since the Middle Ages.

Bialik was raised in Los Angeles, the daughter of first-generation American teachers and documentary filmmakers, and attended public and religious schools. She has guest-starred on MacGyver, The Facts of Life, and Webster, and appeared numerous times on The Tonight Show, Arsenio Hall Show, and other late-night talk fests.

She has pursued numerous causes and interests beyond acting.

In 2007, Bialik earned a doctorate in neuroscience from UCLA, specializing in obsessive-compulsive disorder in adolescents with Prader-Willi syndrome, a rare genetic disorder that causes lax muscle tone, cognitive disabilities, and a chronic feeling of hunger that can lead to life-threatening obesity.

She is devoted to a lifestyle that includes home-schooling and vegan cooking, and serves as celebrity spokeswoman for the Holistic Moms Network. She is the author of a new book, Beyond the Sling: A Real-Life Guide to Raising Confident, Loving Children the Attachment Parenting Way.

She speaks on issues from Jewish parenting to neuroscience to feminism in Hollywood. Her focus on Sunday was on all that Judaism has brought her - joy, tradition, character, and purpose, and how the bat mitzvah provided a framework.

The ceremony offers "the means by which we as women can begin to engage with the divine world," she said. "The bat mitzvah is a tremendous affirmation of our people."

at 215-854-2415, jgammage@phillynews.com, or follow @JeffGammage on Twitter.