When you look at the flowery blue thing in the photo, what do you guess that it is? Would you believe that it’s not a plant, but an animal — and worse yet, a worm? It is a worm, and scientists have nicknamed this crazy-looking creature the “Christmas tree worm,” since it looks a bit like a leafy fir tree. It lives on the Great Barrier Reef, a giant stretch of underwater coral off the coast of Australia. Coral is that beautiful spiky sea shape that looks like a plant itself, but is actually thousands of tiny, donut-shaped animals called coral polyps. They cluster together to make colorful, spiky branches. That means the Reef, which covers 133,000 square miles, is the world’s biggest cluster of living things! The Christmas tree worm hangs onto that coral but doesn’t eat it: it’s a filter feeder, using those fluffy tentacles to suck tiny creatures from the water and stuff them in its mouth. It doesn’t wave those around just to look pretty.
Wee ones: If this worm has 6 layers of spiraling tentacles and its friend has 8, which one has more?
Little kids: If you scuba dive to photograph this worm at 300 feet deep, and so far you’ve swum 100 feet down, how much deeper do you have to swim? Bonus: The Reef covers 133,000 square miles, while the state of California covers 164,000 square miles. Which one is bigger?
Big kids: If you scuba dive at the Reef and swim 200 feet down, then 90 feet up, and then 10 feet back down to take an underwater photo, how deep are you? Bonus: The Reef is home to 125 species, or types, of sharks and rays. If there are 4 times as many types of sharks as rays, how many shark species are there?
Wee ones: The neighbor, with 8 layers.
Little kids: 200 more feet. Bonus: California is bigger, but not by much!
Big kids: 120 feet down. Bonus: 100 shark species (and 25 rays).