roundworms

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What are roundworms? Nematodes, evolution, and biology

By |2018-04-16T09:05:06-07:00May 27th, 2017|Biology|

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 this time, roundworms lived in the ocean. Circulatory system Roundworms were the first kind of animal that was big enough so that some of its [...]

Roundworms, sandboxes, and pets: a project

By |2017-05-27T20:58:03-07:00May 27th, 2017|Biology|

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, and they can make kids get thinner because they don't feel like eating. Roundworms can even make kids go blind if they get [...]

Why do eyes have pupils? Evolution and Biology

By |2019-06-03T18:50:53-07:00May 27th, 2017|Biology|

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 them from being damaged. The origin of eyespots From eyespots to eyes Still the Proterozoic All our biology articles As a side effect, [...]

How do eyes work? Evolution and Biology

By |2019-06-03T16:05:12-07:00May 27th, 2017|Biology|

A flatworm with eye-spots Eyespots came first Living creatures have been able to tell if it's light out or not  for about two billion years. That's when some eukaryote cells evolved to be able to sense changes in their surroundings and react to them. More about eyespots The Proterozoic Eukaryote flagella All our biology articles For [...]

What is a flatworm? Evolution and Biology

By |2019-06-10T15:52:10-07:00May 26th, 2017|Biology|

A flatworm When did flatworms evolve? The first flatworms, or platyhelminthes, probably evolved from something like a hydra about 550 million years ago. What's a hydra? Proterozoic Eon All our biology articles Like all other living things at this time, these early flatworms all lived in the ocean. A flatworm has a body [...]

What does a stomach do? – Digestion and Evolution

By |2017-05-26T19:21:38-07:00May 26th, 2017|Biology|

Fish Stomach The first multi-cellular animals like hydras had no stomachs, or you could say they were all stomach, because they were shaped like a bag. Roundworms, a little later, were shaped like a tube, and the cells along that tube made mucus to protect the tube from the bacteria that digested food [...]

What are intestines? Evolution and Digestion

By |2017-09-17T09:06:21-07:00May 26th, 2017|Biology|

Whale intestines (from Medicine Chest) The first animals to have anything like an intestine evolved around 548 million years ago. These were roundworms, just a few millimeters long, and they had just a simple tube running from their mouth to their anus - no stomach in the middle. But already these roundworm guts [...]