spadefoot, tadpoles, fairy shrimp
Amphibian larval polymorphisms, rarely found in the Midwest, are more common in arid western regions. We have discovered that Plains spadefoot toad, Spea bombifrons Cope, tadpoles occur as carnivorous and omnivorous morphological forms in flooded soybean and corn fields on the Missouri River flood plain of western Iowa. Carnivores have longer snouts, larger beaks with an upper cusp and lower notch, shorter intestines with fewer loops than the omnivores, and they feed on fairy shrimp. A similar polymorphism in Spea multiplicata Cope enhances survival in the desert because the carnivore develops faster after consuming fairy shrimp and is able to metamorphose in rapidly drying ponds. However, the omnivore develops slower in deeper ponds, stores more fat and has better postmetamorphic success. Fairy shrimp ingestion triggers development of the S. multiplicata carnivores, but whether this is also true for S. bomifrons remains to be seen. Distributions and abundance of both carnivorous S. bombifrons tadpoles and fairy shrimp need to be determined across the Great Plains and in Iowa.
Journal of the Iowa Academy of Science
© Copyright 1997 by the Iowa Academy of Science, Inc.
Farrar, Eugenia S. and Hey, Jane D.
"Carnivorous Spadefoot (Spea bombifrons Cope) Tadpoles and Fairy Shrimp in Western Iowa,"
The Journal of the Iowa Academy of Science: JIAS: Vol. 104:
, Article 4.
Available at: http://scholarworks.uni.edu/jias/vol104/iss1/4