Spea multiplicata is one of several species of American spadefoot toad. (a) Young spadefoot toads are called tadpoles and live in water in ponds. S. multiplicata tadpoles show three different phenotypes due to genetic variation. The three phenotypes are: detritus feeder, intermediate and carnivore. Detritus feeders are small, and carnivores are large. Intermediates vary in size between the two extremes. A detritus feeder and a carnivore are shown in Fig. 7.1. [Figure 7.1] Detritus feeders: • eat detritus (small pieces of dead organic matter) and algae (photosynthetic protoctists) • have smooth mouthparts, small jaw muscles and long intestines. Intermediates: : can eat all available food (detritus, algae and fairy shrimps) have teeth-like mouthparts, medium-sized jaw muscles and medium-sized intestines. Carnivores: • eat fairy shrimps and other small animals • have teeth-like mouthparts, large jaw muscles and short intestines. Scientists counted the number of each type of tadpole in two different ponds: pond 1 and pond 2.