Clockwise (from top left): a Scorpion fish, Christmas Tree Worms, a Crocodile fish, and Nudibranch Stripe fish in the documentary “The Last Reef 3D.”
Clockwise (from top left): a Scorpion fish, Christmas Tree Worms, a Crocodile fish, and Nudibranch Stripe fish in the documentary “The Last Reef 3D.”
photos by Luke Cresswell

Slithering slugs that look like Day-Glo jewelry, paper-thin flatworms floating and billowing like silk scarves, swarms of jellyfish, crocodile fish, scorpion fish — these are the tiny creatures of the sea that depend on coral reefs for survival. In the new nature documentary “The Last Reef 3D,” they squiggle and swim in front of your face, daring you to grasp at them. But the film wants to do more than impress with its underwater photography and 3-D effects. It’s a cautionary tale about the fragility of the reefs, but the film could use a little more urgency in making its case.

It begins with a bang — literally: footage of a nuclear blast on the Marshall Islands’ Bikini Atoll, where the United States tested nuclear weapons from 1946 to ’58. The fallout destroyed the undersea reefs. But, left alone for years, those reefs came back, we’re told by the narrator, in a testament to their resiliency.

The film then goes on to describe other threats to coral reefs, which are an essential part of the sea’s ecology. Pollution, urban development, rising water temperatures that increase the water’s acidity — these things and more contribute to the deterioration that’s causing reefs to vanish five times faster than rain forests.

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It’s all very informative and convincing, even at a scant 40 minutes, with beautiful underwater photography and lush music. The film’s opening at the New England Aquarium and Museum of Science is timed for school vacation week but might not appeal to all ages — while older kids could be enthralled, the under-8 set will likely find the science over their heads. Still, the underwater photography amazes. The cinematographer is D.J. Roller, who worked with directors Luke Cresswell and Steve McNicholas on the 2008 IMAX film “Wild Oceans,” and with James Cameron on “Ghosts of the Abyss.” He shot “The Last Reef” over a period of three years. Sites include the reefs of Palau, 500 miles west of the Philippines; Vancouver Island; Mexico; the Bahamas; and French Polynesia, captured by an underwater 4K macro photography rig created specifically for this shoot, according to production notes. This new technology allows tiny sea creatures to explode with vibrant clarity on the IMAX screen.

But the story line is lacking. If reefs can rebuild themselves after nuclear bombing, can’t they survive other endangerments? Toward the end of the film, we’re treated to images of the work of sculptor Jason deCaires Taylor, whose life-size statues of humans form underwater sculpture parks in Mexico and Belize. Deep in the Pacific, the hulking metal of sunken ships and warheads are covered in coral; some decommissioned battleships, we’re told, are now sunk deliberately to encourage the development of reefs. These scenes are as eerie and as peaceful as a graveyard. The images are seductive and exotic, but the message of reef endangerment seems diluted by their presence.