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.
The abdomen contains the insect's digestive tract and reproductive organs, it consists of eleven segments in most orders of insects though the eleventh segment is absent in the adult of most higher orders. The number of these segments does vary from species to species with the number of segments visible reduced to only seven in the common honeybee. In the Collembola (Springtails) the abdomen has only six segments.
The abdomen is sometimes highly modified. In Apocrita (bees, ants and wasps), the first segment of the abdomen is fused to the thorax and is called the propodeum. In ants the second segment forms the narrow petiole. Some ants have an additional postpetiole segment, and the remaining segments form the bulbous gaster. The petiole and gaster (abdominal segments 2 and onward) are collectively called the metasoma.
Unlike other Arthropods, insects possess no legs on the abdomen in adult form, though the Protura do have rudimentary leg-like appendages on the first three abdominal segments, and Archaeognatha possess small, articulated "styli" which are sometimes considered to be rudimentary appendages. Many larval insects including the Lepidoptera and the Symphyta (Sawflies) have fleshy appendages called prolegs on their abdominal segments (as well as their more familiar thoracic legs), which allow them to grip onto the edges of plant leaves as they walk around.
Read more about this topic: Abdomen
Other articles related to "invertebrates, invertebrate":
... The greatest impacts upon invertebrate land animals, such as butterflies or grasshoppers, will be seen in the areas of northward and vertical migration ... The greatest ecological impact concerning invertebrates as a result of climate change will likely be seen in the destruction caused by insects whose populations expand in both range and ...
... Spicer, The invertebrates – a synthesis, 3rd ed, Blackwell, 2001, ch ... Brusca, Invertebrates, 2nd Ed, Sinauer Associates, 2003, ch ... Moore, An Introduction to the Invertebrates, Cambridge Univ ...
... million viewers (15.6% audience share) Marine invertebrates, the descendants of one billion years of evolutionary history, are the most abundant creatures in the ocean ... Many invertebrates have simple nervous systems, but giant cuttlefish have large brains and complex mating habits ... Marine invertebrates have a lasting legacy on land too – their shells formed the chalk and limestone deposits of Eurasia and the Americas ...