annelids

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What are segmented worms? Annelids, evolution, and biology

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

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 [...]

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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 [...]

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