Spring cavefish

Abstract: The first stages in tbe development of the cycloid scales on the spring cavefish, Chologaster agassizi Putnam, are indicated by the development of mesodermal elements, known as scleroblastS, along the lateral line on the caudal peduncle; these structures first appear between three and four weeks of life (Fig. 1). The scleroblasts spread, predominantly anteriorly along the lateral line, less rapidly dorsally and ventrally, and least rapidly caudally. At eight weeks of age, the progressive advancement of the mesodermal elements is complete over the body, and the area of first development, along the lateral line, is re-covered by scale follicles. Subsequent development is characterized by complete replacement of the scleroblastS and the presence of true scales in place of the follicles along the lateral line. Complete squamation on C. agassizi occurs between II and 12 weeks.

Abstract: Over 300 non-accidental animal species are recorded from subterranean (cave and groundwater) habitats in the Upper Mississippi River Valley (UMV) region. Most of these are trogloxenes or troglophiles and these are not restricted to nor morphologically specialized for subterranean habitats. Conspicuous examples are bats, fish, moths, camel crickets, and many kinds of flies. A rich fauna of some 56 species are seemingly obligatory inhabitants of subterranean habitats. Twenty-two species of these are terrestrial, termed troglobites, and 34 species are aquatic, called stygobites. The troglobites include pseudoscorpions, mites, spiders, millipeds, collembolans, bristletails, and a beetle. These generally have smaller distributional ranges, but some do occur in states outside of the UMV region. The stygobites include flatworms, snails, amphipods, and isopods. These generally have larger distributional ranges and most occur in southwestern Illinois, which was near to, but not covered by Pleistocene glacial ice. A subset of stygobites are known only from groundwaters in non-cavernous glaciated regions. Among the vertebrates, ten species of trogloxenic cave-inhabiting bats are known from the UMV. Other vertebrates include the Spring cavefish (Forbesichthys agassizii), three species of plethodontid salamanders, one frog, and a bird that nests in cave entrances. Included among the mammals, other than bats, are the White-footed mouse (Peromyscus leucopus), Eastern woodrat Neotoma floridana, and Raccoon (Procyon lotor).