SEA SOUP: PHYTOPLANKTON and SEA SOUP: ZOOPLANKTON by Mary M. Cerullo, photographs by Bill Curtsinger, Tilbury House Publishers, Gardiner, Maine, 1999 and 2001, both 40 pages, $16.95.

“Imagine that you are setting out on an undersea voyage to meet the most important creatures on earth. You step into your own personal submarine. A flick of a switch magically shrinks you and your ship smaller than the period at the end of this sentence…. You look outside your porthole and come face to face with the strange, amazing life forms that are responsible for all other life in the sea – and for the oxygen we breathe, and the atmosphere that surrounds the earth like a warm blanket.”

Teachers, home-schooling families, and parents and children who care about the environment will be eager to take author Mary M. Cerullo and photographer Bill Curtsinger up on this invitation. “Sea Soup: Phytoplankton” and “Sea Soup: Zooplankton” bring the reader into a beautiful and mysterious, usually hidden-from-sight undersea kingdom. A companion volume, “Sea Soup: Teacher’s Guide,” introduces a rich variety of activities that will give young scientists the hands-on experience that facilitates true learning. It’s a really fascinating voyage.

In a phone conversation, Curtsinger said he was challenged to create the first book in the series. Touring the Phytoplankton Laboratory at the Bigelow Laboratory for Ocean Sciences, he met its director, Robert Anderson. Anderson made an eloquent plea for him to bring phytoplankton – long neglected in the media – to the attention of the reading public. “They lack the color and appeal of birds, insects, and polar bears. They aren’t warm and fuzzy. But they’re critical to the health of the planet,” Anderson told him.

Curtsinger was introduced to Cerullo and the collaboration worked extremely well for both of them as evidenced by the seamless

lend of words and images in these lumes. Still, each encountered challenges in the creative process.

Curtsinger had only five days to do the photographs for “Sea Soup: Phytoplankton.” A sales representative lent him a special microscope between trade shows, but the person who promised to help Curtsinger with the project was hospitalized with pneumonia. “I tried to run as many interesting organisms through that microscope as possible,” Curtsinger said.

He had more time for “Sea Soup: Zooplankton” and went out on a boat in Casco Bay to capture specimens. He stored them in a cooler until he could photograph them in the laboratory. “I wanted everything live. I very often worked at night.”

Looking at the pictures in either book, you’d never guess conditions were anything less than ideal. The details are incredible. Check out the pteropods on pages 32 and 33 of “Sea Soup: Zooplankton.” Some of the photographs are really beautiful. You’ll want to linger over the one showing the mutually beneficial relationship of coral and zooxanthellae on pages 16 and 17 of “Sea Soup: Phytoplankton.”

In a phone conversation, Cerullo, who is the 2001 Lupine Award winner for “The Truth About Great White Sharks,” said she faced two challenges of her own working on the “Sea Soup” books.

The first was to make a serious subject engaging for children. The approach she took was to focus on questions children would ask and field-test them on youngsters. The ones that passed the test are real winners. Parents and children will want to know how phytoplankton help build the largest structures on earth, how zooplankton can cause a submarine to disappear, and who the ghosts of the sea are.

Her second concern was that the study of environmental concerns could lead to pessimism. She wanted to leave young readers with a message of hope. It’s clearly captured in a challenge she issues after explaining how the study of phytoplankton can help scientists learn how to take better care of the ocean.

“They [scientists] are also looking for better answers to many of the questions we have just explored,” she said. “Who will find new answers? Who will come up with new questions? Will it be you?”