The Microscopic Anatomy of Lepidodermella Squamata (Dujardin, 1841)
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Loyola University Chicago Loyola eCommons Master's Theses Theses and Dissertations 1977 The Microscopic Anatomy of Lepidodermella squamata (Dujardin, 1841) Raymond W. Ulbrich Loyola University Chicago Follow this and additional works at: https://ecommons.luc.edu/luc_theses Part of the Biology Commons Recommended Citation Ulbrich, Raymond W., "The Microscopic Anatomy of Lepidodermella squamata (Dujardin, 1841)" (1977). Master's Theses. 2967. https://ecommons.luc.edu/luc_theses/2967 This Thesis is brought to you for free and open access by the Theses and Dissertations at Loyola eCommons. It has been accepted for inclusion in Master's Theses by an authorized administrator of Loyola eCommons. For more information, please contact [email protected]. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. Copyright © 1977 Raymond W. Ulbrich THE MICROSCOPIC ANATOMY OF LEPIDODERMELLA SQUAMATA (DUJARDIN, 1841) by Raymond W. Ulbrich A Thesis Submitted to the Faculty of the Graduate School of Loyola University of Chicago in Partial Fulfillment of the Requirements for the Degree of Master of Science December 1977 ACKNOWLEDGMENTS I would like to extend my thanks to the members of my thesis committee for their help and direction in the preparation of this work. The Director of my thesis was Dr. Clyde E. Robbins, and the other members of the committee were Fr. Walter P. Peters, S.J., and Dr. Boris E.N. Spiroff. My thanks are also extended to my family and friends for their support and encouragement. ii LIFE The author, Raymond W. Ulbrich, is the son of Edmund Peter Ulbrich and Willie Lucille (Gilmer) Ulbrich. He was born January 27, 1943, in Detroit, Michigan. His elementary education was obtained in the parish school of Far mington, Michigan, and secondary education at the University of Detroit High School, Detroit, Michigan, where he graduated in 1960. In September, 1960, he entered Loyola University of Chicago, and was awarded the Bachelor of Science degree with a major in biology in June, 1965. iii TABLE OF CONTENTS Page ACKNOWLEDGMENTS ii LIFE iii CONTENTS OF APPENDICES iv INTRODUCTION 1 LITERATURE REVIEW 2 LIFE HISTORY 7 METHODS AND MATERIALS 10 DISCUSSION 14 SUMMARY 24 LITERATURE CITED 25 APPENDIX A 28 iv CONTENTS FOR APPENDICES Page LEGEND FOR APPENDIX 29 PLATE I 30 Figure 1. Whole mount of Lepidodermella sguamata (Dujardin, 1841). Figure 2. Cross section through head. Figure 3. Cross section through head. Figure 4. Cross section through head. PLATE II 32 Figure 5. Cross section through head. Figure 6. Cross section through pharynx. Figure 7. Cross section through pharynx. Figure 8. Cross section through junction of pharynx and mid-gut. PLATE III 34 Figure 9. Cross section through junction of pharynx and mid-gut. Figure 10. Cross section through mid-gut. Figure 11. Cross section through mid-gut. Figure 12. Cross section through mid-gut. PLATE IV 36 Figure 13. Cross section through mid-gut. Figure 14. Cross section through mid-gut. Figure 15. Cross section through intestine. Figure 16. Cross section through intestine. PLATE V 38 Figure 17. Cross section through intestine. Figure 18. Cross section through intestine. Figure 19. Cross section through intestine. Figure 20. Cross section through intestine. v Page PLATE VI 40 Figure 21. Cross section through intestine. Figure 22. Cross section through intestine. Figure 23. Cross section through intestine. Figure 24. Cross section through intestine and beginning of caudal fork. PLATE VII 42 Figure 25. Cross section of intesting with longitudinal section of caudal for~. Figure 26. Cross section through intestine. Figure 27. Longitudinal section of caudal fork. Figure 28. Cross section through intestine. PLATE VIII 44 Figure 29. Longitudinal section of caudal fork. Figure 30. Longitudinal section of tip of caudal fork. Figure 31. Cross section through intestine. Figure 32. Cross section through intestine. PLATE IX 46 Figure 33. Cross section through intestine. Vi INTRODUCTION Lepidodermella squamata (Dujardin, 1841), a common fresh-water gastrotrich, is the subject of this research thesis. Considering the amount of information available in biology, our knowledge of the gas trotrichs is, at best, sketchy. Lepidodermella was first described by Dujardin in 1841. Until 1889 when Zelinka published his major work on the gastrotrich anatomy, little was known about these animals. Remane in 1936 published what could be considered a summation of all the available information on the gastrotrichs. The work between 1936 and the present time has been either of a taxonomic or eco~ogical nature or a combination of both. It has only been recently that any work of a detailed nature has been done on these animals; the Riegers and their associates (1976) have made several stud ies of an ultrastructural nature on gastrotrichs. Excepting the taxonomic, ecological, and the detailed ultrastruc tural studies, there exists very little information which deals with the internal anatomy of these animals. It is the purpose of this thesis to describe the microscopic anat omy of Lepidodermella squamata through a study of serial transverse cross-sections. Only then can it be determined if this species fits the "generalized" structure described for all gastrotrichs. 1 LITERATURE REVIEW The gastrotrich, Lepidodermella squamata, was first described by Dujardin in 1841, but it was not until 1889 that any detailed study of the gastrotrichs was published. In 1889 Zelinka published a very com plete study of both the external and internal anatomy of many gastro trich species. His purpose was not to study the gastrotrichs exclu sively, but rather to establish a phylogenetic relationship between them and the rotifers. Each of these groups is considered to be a class in the phylum Aschelminthes. In the original material written by Zelinka, the genus Lepidoderma appears to be equivalent to the genus that we know as Lepidodermella. In 1933, Blake proposed that the genus name, Lepidodermella, be substi tuted for Lepidoderma. In 1936, Remane published a work on gastrotrichs, a work now rec ognized as a complete summary of all of the available information up to that year. He had surveyed the microscopic fauna of many European re gions looking for new species of gastrotrichs. In addition to the tax onomic studies, he incorporated much of Zelinka's work with his own relative to the microscopic anatomy and the end result was almost a "handbook" on the gastrotrichs. Lepidodermella squamata has been the subject of four extensive works in the United States. The first of these, published by Packard 2 in 1936, studied the life history of this species and was also the first to suggest using malted milk powder as a culturing medium. Pack ard followed the progeny of a single animal for as many as six consecu tive generations detailing the life span, the number of eggs produced by a single individual, and the time required for the development of an egg. Brunson (1949) provided a more detailed study of the biology and some of the embryology of this specie& For culturing, he used Pack ard's malted milk medium, but he also achieved limited success using depleted protozoan cultures. These depleted cultures would sustain a population of gastrotrichs but were not suitable for pure-line studies. In collect~ng field samples for culturing in the laboratory, Brunson stressed the importance of conditioning the animals for lab oratory culture. He accomplished this by adding sample debris collect ed along with the animals to the culture fluid, waiting from one to four weeks, removing half of the volume and replacing it with new medium. His embryological studies, although not complete, provided more information than had existed previously. He studied the number of eggs produced by each individual and the age at which the eggs were produced. His attempts to study development within an individual egg 3 were not completely successful. He was unable to follow cleavages past the four-cell stage and his observations of later stages were incomplete. Goldberg, in 1949, also studied the biology of this species and arrived at many of the same conclusions as Brunson. Goldberg dealt primarily with the biology and not with the embryology of this species. He achieved success utilizing rice grains in the culture fluid. He was unable, however, to observe the opisblastic or "winter" egg that had been described by Brunson. The most definitive embryological study of Lepidodermella squa mata was the subject of a doctoral dissertation by Sacks in 1955. His work details the stages in the embryology from the time of oviposition until the egg hatches as a new individual. Sacks found, as did Brunson, that generally Lepidodermella pro duces a maximum of four eggs in its life span. The average life span of the gastrotrich was found to be 10.11 days; and the eggs are pro duced when the animal is 1.50, 2.18, 2.96, and 3.72 days old respect ively. The average hatching time was found to be 1.12 days. Sacks compared his data with Brunson's and felt that any devia tions in the average figures could be due to differences in culturing technique or temperature. 4 His observations of the embryology were facilitated by a water immersion objective. Using this objective, he followed the develop ment from the time a polar body is given off and cleavage begins, until the new gastrotrich makes its way out of the shell. When the new animal emerges from the shell, it is quite trans parent and smaller than the adult. The most distinguishing feature is the presence of refractile granules in the gut. Although the exact nature of these granules is unknown, Zelinka (1889) considered them to be reserve food. Sacks feels that since they are released into the lumen of the gut and eliminated from the animal within two hours of hatching, the current view that they are excretory in nature seems more likely.