An annelid, or segmented worm When did annelids evolve? Roundworms probably evolved into segmented worms, or annelids, about 545 million years ago. What's a roundworm? More about the Proterozoic All our [...]
Nematodes, also called roundworms, in a jar Evolution of roundworms Roundworms, or nematodes, probably evolved from the earlier flatworms about 548 million years ago. Like all other living things at [...]
Sandboxes can carry roundworms Roundworms are a serious health problem today in North America, especially in warm places where the cold doesn't kill them in the winter. Roundworms make kids tired, [...]
Fish gills The first cells, which evolved about 3.8 billion years ago, needed carbon dioxide to live and not oxygen. They needed the carbon dioxide to help them break down [...]
Caribbean woman swimming with two children: lungs project Your lungs as swim bladders Your own lungs still can act a little like swim bladders. Here's a lungs project: When you [...]
Reproduction: Hydra budding new hydras RNA and DNA molecules The first form of reproduction began about four billion years ago, when first RNA molecules and then DNA molecules began to make [...]
Fish eggs - eggs science project Different types of eggs This is a simple eggs science project. Check out different kinds of eggs and you'll see the difference between fish [...]
Cats have pupils that can get bigger or smaller. Eyes start to focus light By around 550 million years ago, some kinds of worms evolved eyespots sunk into their heads to protect [...]
A network of neurons One-celled creatures like bacteria don't have neurons, because they can communicate within themselves through the use of enzymes, but all multicellular animals do have neurons. The [...]
The yellow string is one of the arm nerves of a cat By around two billion years ago, some eukaryote cells were able to sense changes in their surroundings and [...]
