annelids

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27 05, 2017

What are segmented worms? Annelids, evolution, and biology

By |2019-01-27T20:52:49-07:00May 27th, 2017|Biology|0 Comments

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 biology articles What were annelids like? The earliest annelids all lived in the ocean, as most kinds of annelid still do today. Some [...]

26 05, 2017

What are intestines? Evolution and Digestion

By |2019-09-21T15:05:41-07:00May 26th, 2017|Biology|0 Comments

Whale intestines (from Medicine Chest) When did intestines evolve? The first animals to have anything like an intestine evolved around 548 million years ago. These were roundworms, just a few millimeters long. Roundworms had just a simple tube running from their mouth to their anus - no stomach in the middle. What's a [...]