Effects of intermittent feeding on the growth of oophagous (Chirixalus eiffingeri) and herbivorous (Chirixalus idiootocus) tadpoles from Taiwan

Abstract

The effects of intermittent feeding on the growth of oophagous Chirixalus eiffingeri and herbivorous Chirixalus idiootocus tadpoles were studied. Tadpoles were fed, once every 1, 2, 4, 8, 14, or 20 days (feeding treatments 1D, 2D, 4D, 8D, 14D, and 20D, respectively). At each feeding, C. eiffingeri were given yolk from chicken eggs, and those of C. idiootocus were given boiled spinach, ad libitum. For each species, each treatment consisted of 12 replicates of one tadpole each. For C. eiffingeri, the 1D feeding treatment was eliminated because the tadpoles were unwilling to eat daily. Chirixalus eiffingeri tadpoles in the 2D and 4D feeding treatments grew fastest, while tadpoles in the 20D treatment grew slowest. At least five tadpoles from each treatment, except 20D treatment, reached metamorphosis. Chirixalus idiootocus tadpoles in the 1D and 2D feeding treatments showed signs of growing, but tadpoles in the other four treatments did not grow at all. Only tadpoles in the 1D treatment reached metamorphosis. In another experiment, yolk digestion in the stomach of C. eiffingeri tadpoles was monitored. Yolk use was slow and egg yolk remained in the stomach for at least 8 days. Chirixalus idiootocus tadpoles could not tolerate long periods without food, probably because their digestive tract had a short clearance time and their stomach was incapable of long-term food storage. In contrast, between feedings, C. eiffingeri tadpoles seemed to mobilize food stored in their stomach, providing a continuous supply of nutrition to facilitate normal growth and development. These results and observations provide important insights into the maternal brood care of female C. eiffingeri.