RECIPE FOR A REEF
by Kathy Kranking
It takes a special blend of things to make a coral reef!
coral, anemones, fish, sea fans, crabs, sponges, and hundreds of other creatures
PREHEAT: Coral reefs and the creatures in them need sunlight and clear, warm water to grow. No wonder they’re found in tropical waters around the equator.
PREPARE AHEAD OF TIME: Reefs are built by tiny animals called coral polyps. It takes thousands or even millions of years for a coral reef to form.
MIX TOGETHER an amazing variety of animals.
ENJOY a feast of color and life!
That’s the basic recipe for a coral reef. To learn more about how reefs are made, keep reading.
A PILE-UP OF POLYPS
A coral reef is made by tiny animals called coral polyps (PAH-lips). There are two kinds: hard corals and soft corals. Hard corals are the kind that make reefs. (More about soft corals later.)
Here’s how a reef is made: Each hard coral polyp builds a little stony “house” around itself. The house is the polyp’s skeleton. When polyps die, the hard skeletons are all that is left of them. Other polyps build new houses on top of the old ones.
After many thousands of years of the skeletons piling up like this, a coral reef is formed. Some reefs are gigantic. The Great Barrier Reef, in Australia, is the longest reef in the world. It’s made up of more than 1,250 miles of piled-up polyp skeletons!
Though the corals that build reefs grow slowly, others can grow faster—up to 8 inches a year!
POLYPS UP CLOSE
A hard coral polyp’s body is a tiny tube. One end of the tube is attached inside the polyp’s stony house. The other end has tentacles around the rim. They make the polyp look like a tiny flower.
Polyps feed by reaching out with their tentacles to catch tiny animals floating past. The tentacles of each polyp move the food to the polyp’s mouth, in the center of the tentacles.
A COLLECTION OF CORALS
Soft coral polyps look similar to hard coral polyps, but they don’t make stony reefs the way hard corals do. Instead, they make soft, leathery branches and stalks. Unlike their hard coral cousins, soft corals sway with the movement of the water. They look kind of like plants. As you can see here, both hard and soft corals come in many amazing shapes and colors!
This school of ribbon sweetlips (top left photo) makes a colorful show as it swims along the reef. Sweetlips get their funny name because of their big, puffy-looking lips. These fish are also called grunts, for the pig-like grunting sounds they make.
The porcelain crab uses its claws to protect itself. But not the way you might think. Instead of pinching when it’s attacked by an enemy, it just sheds one or both of its claws! If the crab is lucky, the claws will distract the enemy while the crab scurries off. Later, the claws will grow back.
A BALLED UP
This bristly ball is made up of the arms of a feather star. Feather stars are cousins of sea stars. They can have as few as 5 arms or as many as 200! Tiny hairs on the feathery arms catch food that floats in the water. With the help of mucus, the hairs move food down the feather star’s arms to its mouth.
Sea anemones (uh-NEM-uh-nees) will sting most fishes. But this Clark’s anemonefish can live safely in a sea anemone’s tentacles without being stung. See all those bright orange dots? They’re the anemonefish’s eggs! Most fishes just lay their eggs and leave. But this mom takes care of her eggs, keeping them clean and chasing off intruders until they hatch.
You have to look closely to see these tiny Denise’s seahorses. They perfectly match the soft coral sea fan they’re clinging to. These tiny fish are homebodies—they’ll stay in the same coral their entire lives.
A coral reef has lots of things growing all over it, including sponges! The sponge here is bluish and branchy, but sponges come in many different colors and shapes. Sponges can make good hiding places for reef creatures, from fish to crabs to shrimps.
With the right temperature, preparation, and ingredients, you have the recipe for making a beautiful, lively coral reef. Hope you’ve gotten your “fill”!
"Recipe for a Reef" originally appeared in the November 2017 issue of Ranger Rick magazine.
Click here for a close-up view of the photos.