part_of adult body adult hindgut adult rectal sac Fig. 6-1, Fig. 6-2, Fig. 6-3, Fig. 10-1, in Biology of Ticks ISBN:0-19-505910-7. Large thin-walled organ located in the posterior region of the body. Connected to the midgut by the intestine and to theexterior of the body by the anus. A pair of malpighian tubules connect to the rectal sac on either side. The rectal sac is filled with guanine crystals and fills with hematin and other wastes from the midgut during blood feeding. The hindgut is believed to be responsible for some water and selective salt resorption and may also be responsible for excreting nitrogenous wastes. The rectal sacis a simple sac in ixodid ticks, but bifurcated in argasid ticks. TADS:0000166 TADS:0000166 default_namespace portion of tissue