NOT ON EXHIBIT
At the Aquarium
How do you keep a coral reef exhibit clean? Our aquarists try to mimic relationships that exist in the wild, keeping everything in balance. Snails and hermit crabs are introduced to help scour exhibit surfaces. Tangs and surgeonfishes pick, tear and rasp away at the rocks to keep algae in check. There’s even a fish nicknamed the lawnmower blenny that scrapes away at brown algae film on the rocks. “All these animals have jobs to do,” says Curator Paul Clarkson, “consuming things we don’t want in the exhibit, and helping keep the coral healthy.”
This animal’s name comes from the hammer- or anchor-shaped tips of its tentacles. An anchor coral colony may look peaceful, but it packs a powerful punch. Special “sweeper” tentacles—up to several inches long—reach out to inject poison into neighbor colonies that try to take over its turf—a good strategy in a crowded coral reef.
Corals can take many forms. Small-polyp “stony” corals deposit a hard skeleton, forming the “old growth” of the reef. Large-polyp stony corals—like the anchor coral—have a hard skeleton beneath and soft tissue above. Still other corals are entirely soft and don’t deposit any calcium carbonate. All three types can be found in a single coral reef.
While the bright colors of coral reefs are a sign that they’re healthy, warmer ocean waters are killing some corals, leaving only bleached-white skeletons. Corals build rocky skeletons from calcium and carbonate, chemicals found naturally in the ocean. But oceans are absorbing enormous amounts of carbon pollution, making them more acidic, which soaks up loose carbonate. Without that critical building block, it's much harder for corals to form a reef.
The coral itself isn’t the only thing affected. A coral reef is a living oasis where spectacular sea life thrives. This beauty and bounty provides food and shelter for those who live nearby. Bleached reefs are more vulnerable to other ocean changes. If we slow down ocean changes now, we can give the whole community a chance to survive.
Learn more about our “Hot Pink Flamingos” special exhibition.
Corals carry venom in nematocysts—tiny stinging cells on the tips of their tentacles.
This family of corals have separate male and female colonies. Fertilization happens when eggs and sperm are released and meet in mid-water.
One or many? If we think of corals as communities, then the residents are “polyps”—individual animals joined at their base by their hard skeletons.