"But look closer. That fuzz is actually made up of tiny spines ... thousands of them. Some long and spiky, others rounder. Mixed in are miniature tube feet with grabby little suckers on the ends. They use them to meticulously sift the sand and pass the grains down the line ... until they reach the sand dollar's mouth at the very center of its underside, buried under all those spines."
"Sand dollars eat sand. They're after the algae and bacteria that coat the grains. And these sand dollars can also stand themselves up on their sides to use the long spines around their edges to trap tiny plankton floating by. So what about that part that looks like a flower with five petals? It's called the petaloid. They have special tube feet there that help the sand dollar breathe, absorbing oxygen out of the water."
Pacific sand dollars are flat, fuzzy-looking echinoderms covered in thousands of tiny spines and miniature tube feet that work together to sift sand and move grains toward a central mouth on the underside. They eat the algae and bacteria coating sand grains and can stand on edge to trap plankton with long edge spines. The petaloid, a five-petaled pattern, contains specialized tube feet used for gas exchange. Sand dollars are flat sea urchins adapted to sandy, turbulent undersea environments; their flattened shape reduces drag. Young sand dollars ingest heavy magnetite grains, which accumulate as ballast to help them remain on the seafloor.
Read at Kqed
Unable to calculate read time
Collection
[
|
...
]