The simplest multicellular beasts on earth, sponges are collections of loosely organized single cells with no true organs or tissues. Follow writer Henry Genthe from the bottom of the Pacific to Caribbean coral reefs as he discovers these deceptively simple creatures at home and at the cutting edge of medical research.
Approximately 10,000 species of sponges live in fresh and salt water, their forms ranging from delicate foot-high vases to eight-foot-tall giants. "Most sponges," Genthe notes, "are barely recognizable as animals and for years were considered to be plants." Their passive and helpless appearance is, however, deceiving. With a shield of toxins and sharp, microscopic spikes, called spicules, which help hold them together, sponges expertly deter enemies and beat out more complex creatures for solid space in the crowded underwater world. There, they feed on plankton and other microscopic fare pulled in through tiny pores. But don't think they do all this sitting still: despite appearances, sponges can actually move!
Now, sponges and their toxins are finding a niche in medical research. "Organisms that appear to defend themselves chemically are of great interest to us," notes John Faulkner, professor of marine chemistry at Scripps Institution of Oceanography, in La Jolla, California. Included in the growing roster of potentially beneficial sponge molecules are ones that fight inflammation and cell division.
It's all in a day's work for sponges. Not bad for a "primitive" animal.