Honolulu Star-Advertiser © Susan Scott
August 24, 2007
Last month, University of Washington researchers discovered an entire reef made of glass sponges, 650 feet below the surface.
This ancient sponge reef, 2,000 feet long and 10 feet tall, is so full of starfish, crabs, shrimp, fish, worms and snails that scientists there are calling it a living hotel.
It’s the Hotel California for some species. Small crabs sometimes swim into the opening, molt there and are then too big to get out. These creatures spend the rest of their lives inside the sponge.
Mated pairs of shrimp also check in to glass sponges called Venus flower baskets and never leave. Like the crab, the shrimp grow too large to get out the narrow top, but they don’t mind. They settle down in their glass house and raise families. Their tiny larvae are able to swim out the top.
In Japan these shrimp represent a happy marriage, and the beautiful sponge is a traditional wedding gift.
Sponges are such simple animals people once thought they were plants. A sponge has no nervous system, no muscles, no stomach, no eyes. It feels no pain and can’t move. But in spite of those limitations, sponges still manage to stand tall, eat, reproduce and defend themselves.
Sponges keep their shape by forming spicules, tiny rods that make intricate scaffolding for the sponges’ cells. In glass sponges these spicules consist of silica, a common material used in glass, concrete and abrasives.
Glass sponge spicules can stick into skin and mouths, and predators keep their distance. Other sponges, such as Hawaii’s orange fire sponge, contain, as well as glass shards, skin-burning chemicals.
Inside their spicule skeletons, sponge cells align themselves to form canals filled with tiny, beating hairs. These hairs move water into the sponge through pores at the surface and out through a large central canal.
The incoming water brings oxygen and food in the form of bacteria, algae, single-celled animals and other creatures’ cast-out sex cells. Even though some sponges grow large skeletons, their cells stay the same tiny size and they can never eat anything larger than themselves.
Besides food and oxygen, sponges also sometimes draw in sponge sperm, which rides in the creatures’ exit currents.
Most sponges are hermaphrodites, bearing eggs and sperm. If one inhales another’s sperm, it fertilizes waiting eggs. These stay inside, protected and nourished, until the youngsters can fend for themselves. Then they’re ejected in the outgoing stream.
Since getting sperm that way is chancy, sponges can also reproduce by cloning. If you press a sponge through silk cloth, the sponge separates into single cells. If these fall into a dish of sea water, they creep around until one runs into another. The two stick together and begin making a skeleton. In this way new sponges are created, each identical to the original.
Glass sponges are deep-sea creatures that grow 1 1/2 feet tall and live 100 years. When they die, others grow on top of them.
Washington’s newly discovered glass sponge reef needs immediate protection from trawlers and longline fishers. We humans might never be able to check in to this extraordinary hotel, but we can look into its windows and dream.