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Aggregation No. 1The Trouble with Jellyfish from noon to 9 p.m. Friday at Le Laboratoire Cambridge, 650 E. Kendall St., Kendall Square. Free.

This contemporary art installation by Mark Dion and marine biologist and author Lisa-ann Gershwin looks into the stunning world of the jellyfish and how their growth have become a danger to oceans worldwide. Expect a six-foot tank of live moon jellies; a “Hypoxia” simulation chamber in which visitors can experience low oxygen levels safely, mimicking the effects of an ocean “dead zone” like the ones created in areas with overpopulation of jellyfish; and unique cupcakes at the Bloom Bakery, where Harvard University students have designed a jellyfish-derived ingredient to organically enhance moisture in the baked goods of chef Renae Connolly. Among other features, there will also be a mock classroom talk with Gershwin examining jellyfish-related problems and a look at how a jellyfish harvest led to “an unparalleled absorbency potential utilized in paper towel design.” The exhibition begins Friday and remains open through Jan. 2, open noon to 9 p.m. Wednesdays through Fridays and 11 a.m. to 10 p.m. Saturdays. Information is here.

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Aggregation No. 2Strip Zeppelin with Niki Luparelli at 8 p.m. Friday at Oberon, 2 Arrow St., Harvard Square. Tickets are $20 to $30.

This blend of live Led Zeppelin tunes with burlesque and aerial artists comes from Niki Luparelli, producer of shows celebrating such icons as David Bowie, James Bond, Madonna and Prince. Burlesque performers are to include the Lipstick Criminals, formerly known as the Babes in Boinkland; Bettysioux Tailor; Malice in Wonderland; acrobatic aerial ecdysiast Fonda Feeling; and silks specialist Zoso LaRose. “Always sassy, brassy, and nigh to bursting from her bustier, Luparelli, cocktail in hand, leads her Zeppelin band the Misty Mountains and a breathtaking array of neo-burlesque performers eager to give you every inch of their love in tribute to the original Hammer of the Gods,” goes the blistering blurb for this event. Information is here.

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Aggregation No. 3Danehy Park Family Day from 11 a.m. to 4 p.m. Saturday at Danehy Park, at 99 Sherman St., North Cambridge (near Garden and New streets). Free.

The 20th Annual Danehy Park Family Day includes music and other performances at the children’s stage, roving performers, children’s amusement rides and arts and crafts, as well as free hot dogs, chips, sodas, T-shirts and kites while supplies last. The free event, sponsored by the city, attracts more than 4,000 people annually. The 55-acre Danehy Park can be reached by the 74 or 78 bus from Harvard Square; the 83 bus from Central Square; or by shuttle bus from the Alewife MBTA Station. Picnics and lawn chairs are encouraged, and the rain date is Sunday. Information is here, or people can call (617) 349-4301.

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Aggregation No. 4The Ig Improbable Lectures at MIT from 1 to 3 p.m. Saturday at the Massachusetts Institute of Technology’s Building 10-250, also known as the Maclaurin Buildings, at 222 Memorial Drive. Free.

Winners of Thursday’s Ig Nobel prizes – for achievements in science “that first make people laugh, and then make them think” – return for lightning-fast lectures that try to explain what they did and why. The scientists get a whole five minutes each to describe and/or defend their work, then respond to audience questions. Information is here.

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Aggregation No. 512th annual Revels RiverSing from 5 to 7:30 p.m. Sunday in Harvard Square and by the Weeks Footbridge along the banks of the Charles River. Free.

Cambridge’s traditional sendoff to summer and welcoming of the months of foliage, Halloween, apple cider and hot chocolate is here, led as it has been for the past decade by the nonprofit Revels organization. It includes the 100-member RiverSing Chorus of adults and children, traditional New Orleans band Eli & the Hot Six, led by local legend Eli Newberger, local percussion ensemble Bloco AfroBrazil, a folk band, acrobats and street performers, giant puppets from Sara Peatie’s Puppeteers Cooperative and the magical butterflies of Gabriel Q.

It starts with a 5 p.m. gathering in Winthrop Park for family festivities including Honk! band music, face painting and hula-hooping. At 5:45 p.m. comes a parade to the Charles River for 6 p.m. singing and poetry along the Charles, including an improvisational call-and-response between saxophonists Ken Field (on stage) and Stan Strickland (floating along the Charles in an illuminated boat decorated to honor the sun and moon). Information and printable lyrics are here.