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Abdominal organs can be highly specialized in some animals. For example the stomach of ruminants (a suborder of mammals) is divided into four chambers - rumen, reticulum, omasum and abomasum.
Invertebrates
The invertebrate abdomen is built up of a series of upper plates known as tergites and lower plates known as sternites, the whole being held together by a tough yet stretchable membrane.