Fig. 7. Food density dependence of isthmus/TB pumping and peristalsis. When (A) C. elegans, (B) P. pacificus, (C) Cephalobus sp. DWF1301, or (D) Panagrolaimus sp. PS1159 animals were placed in dilute food conditions compared to normal conditions (see Materials and methods), isthmus/TB pumping/peristalsis rates were reduced whereas corpus pumping rates were unchanged or increased. Asterisks indicate statistically significant differences between dilute and normal conditions by two-tailed t-test (**P<0.01).