How the ghost shark lost its stomach
Lack of digestive organ in fish and other animals linked to genes
By Susan Milius, 10:57 AM December 4, 2013
Animals from lungfish and ghost sharks to platypuses have lost their acid-making stomachs over evolutionary time, and researchers have now traced the genetic changes behind these stomach upsets.
True stomachs with digestive glands that concentrate acid and release protein-cutting enzymes called pepsins evolved with vertebrates. The gastric glands arose some 450 million years ago but have dwindled away at least 15 separate times across the animal tree of life, explains Filipe Castro of the Univ...
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