The Position of Acoelomorph Turbellarians Among Lower Worms

无形虫是一组结构相对简单的蠕虫，因此，一些生物学家认为它们代表了所有多细胞动物中最基本的形式。无形动物通过多核组织来消化食物，而不是在肠道的腔或腔中，它们的神经系统只是松散地组织成可以与其他动物的大脑和神经索相比的浓度。分类学家主要根据生殖器官的结构将其分为17科，但未能解释这些科彼此之间或与其他动物类群（包括其他扁虫）之间的关系。为了更好地理解这些基本的动物形态是如何与低等动物系统相适应的，无形目动物和其他无脊椎动物的成员被认为与电子和荧光显微镜有关，特别是观察体壁的肌肉组织和生殖器官以及头部腺体和感觉器官复合体的精细结构。通过这种检查识别的特征将被应用于重建无形科之间的关系以及无形科与其他低等无脊椎动物群体的关系。这项研究的最终目标是了解这些低等蠕虫多样性的原因。这项研究将有助于我们理解一个非常“原始”或简单的动物群体之间的关系，并将有助于澄清或解释地球上许多动物多样性群体的辐射。＊＊＊

9419723 TYLER The Acoelomorpha is a group of worms of comparatively simple structure, and, accordingly, some biologists consider them to represent the most basic form of all multicellular animals. Acoelomorphs digest their food with a multinucleate mass of tissue instead of in the lumen or cavity of a gut, and their nervous system is only loosely organized into concentrations that could be compared to the brain and nerve cords of other animals. Taxonomists divide the group into 17 families, largely on the basis of the structure of the reproductive organs, but have fallen short of explaining how these families relate to each other or to other animal groups, including other flatworms. To better understand how these basic animal forms fit into the system of lower animals, members of the Acoelomorpha and other invertebrates believed to be related with electron and fluorescence microscopy, specifically looking at the musculature of the body wall and reproductive organs and the fine structure of the complexes of glands and sensory organs in the head. The characters discerned through this examination will then be applied to reconstructing relationships among acoelomorph families and relationships of acoelomorphs to other lower invertebrate groups. The ultimate goal of this research is to understand the causes of the diversity of these lower worms. %%% This study will contribute to our understanding of the relationships of a very "primitive" or simple group of animals and will help clarify or explain radiations of many groups in the animal diversity of the earth. ***