Definitions for "Opisthosoma"
Portion of the body posterior to the legs in a tick or mite.
(op - iss - tho - so -mah) Portion of the body posterior to the legs. In horseshoe crabs, it is the pentagon-like region behind the "horseshoe."
The opisthosoma is the posterior portion of the arachnids body behind the prosoma. The number of segments and appendages on the opisthosoma vary. In general, appendages are absent or reduced, although in horseshoe crabs they persist as large plate-like limbs, called branchiophores, bearing the book gills, and that function in locomotion and gas exchange.
The "rearward" section of the tarantula that contains the spinnerets, the book lungs, the epigastric furrow, and the anus. The heart is also inside the opisthsoma, so be careful! In the case of most New World species, the opisthosoma has urticating hair. Also called the "abdomen".