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Internal Fluid Transport in Early Animals

By Michael Alan Prestwood

Tue 24 Feb 2026
Published 2 months ago.
Updated 3 days ago.
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Before true circulatory systems evolved, early animals began moving fluids through internal body spaces, helping nutrients reach deeper tissues and waste move out.

Internal Fluid Transport in Early Animals

~550 Million Years Ago (+/- 25 million)
Diffusion and body-cavity circulation

As multicellular animals grew larger, simple diffusion became insufficient to move nutrients and remove waste. Early animals evolved internal fluid movement within body cavities, allowing nutrients to circulate beyond direct cell-to-cell contact.

 

— map / TST —

Michael Alan Prestwood
Author & Natural Philosopher
Prestwood writes on science-first philosophy, with particular attention to the convergence of disciplines. Drawing on his TST Framework, his work emphasizes rational inquiry grounded in empirical observation while engaging questions at the edges of established knowledge. With TouchstoneTruth positioned as a living touchstone, this work aims to contribute reliable, evolving analysis in an emerging AI era where the credibility of information is increasingly contested.
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