Evolution of the Cuticle in the Lower Eumetazoa

Rieger, Reinhard M.

doi:10.1007/978-3-642-51593-4_23

Cited by 35 publications

(15 citation statements)

References 48 publications

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“…In contrast, the dorsal epidermis of aplacophoran molluscs and the dorsolateral zone of polyplacophorans are covered by a «true» (Rieger, 1984) chitinous cuticle consisting of a very thin (about 50 nm) epicuticula and a much thicker (l-100um) endocuticula (Beedham & Trueman, 1968;Haszprunar, 1987b). In this cuticle the bases of scales or spines are embedded, which form a dense cover of the dorsal surface.…”

Section: Cuticle Spicules Shell Plates and Shellmentioning

confidence: 99%

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The first molluscs ‐ small animals

Haszprunar

1992

Bolletino di zoologia

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Recent data on early Cambrian fossils from various sources suggest that the earliest molluscs up to the conchiferan level of organization were animals of very small (1-2 mm) size. These data are in contrast to current theories on the origin and evolution of molluscan organ systems, most of which postulate an increase of size at the beginning of molluscan evolution. The evolutionary and functional implications and constraints of an original small body size on molluscan locomotion, respiration, excretion and reproduction are discussed. Based on recent fine-structure work the evolutionary history of the Mollusca is reconsidered. In addition, some alternative ideas are presented to explain the origin of the mantle cavity (originally also used as a fertilization chamber?), ctenidia (originally for ventilation rather than for respiration?), coelom (originally a : gono-nephrocoel?), and pecularities of the alimentary tract.KEY WORDS: Mollusca -Origin and evolution -Implications ofsmall size. ACKNOWLEDGEMENTS

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Section: Cuticle Spicules Shell Plates and Shellmentioning

confidence: 99%

“…As reviewed by Rieger (1984), this type of cuticle may be important to regulate the import of dissolved organic matter (DOM) between seawater and organism. Indeed, such a type of glycocalix is found in various groups of (primarily or secondarily) small spiralians (see Rieger & Rieger, 1976;Rieger, 1984).…”

Section: Cuticle Spicules Shell Plates and Shellmentioning

confidence: 99%

The first molluscs ‐ small animals

Haszprunar

1992

Bolletino di zoologia

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“…Using possible elements of autonomy, feasible animal body plans seem to have been explored. The generation of the different, more or less enclosing integuments was one of the functions involved (Bereiter-Hahn et al 1984;Lillywhite and Maderson 1988;Rieger 1984;Willmer 1990). A host of different organs, appendages and functions was generated, which stabilized the animals in different ways against the fluctuations of their environment.…”

Section: Multicellularitymentioning

confidence: 98%

The theory of increasing autonomy in evolution: a proposal for understanding macroevolutionary innovations

Rosslenbroich

2009

Biol Philos

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Attempts to explain the origin of macroevolutionary innovations have been only partially successful. Here it is proposed that the patterns of major evolutionary transitions have to be understood first, before it is possible to further analyse the forces behind the process. The hypothesis is that major evolutionary innovations are characterized by an increase in organismal autonomy, in the sense of emancipation from the environment. After a brief overview of the literature on this subject, increasing autonomy is defined as the evolutionary shift in the individual system-environment relationship, such that the direct influences of the environment are gradually reduced and a stabilization of self-referential, intrinsic functions within the system is generated. This is described as relative autonomy because numerous interconnections with the environment and dependencies upon it are retained. Features of increasing autonomy are spatial separations, an increase in homeostatic functions and in body size, internalizations and an increase in physiological and behavioral flexibility. It is described how these features are present in different combinations in the major evolutionary transitions of metazoans and, consequently, how they should be taken into consideration when evolutionary innovations are studied. The hypothesis contributes to a reconsideration of the relationship between organisms and their environment.Keywords Trends Á Biological autonomy Á Macroevolution Á Evolutionary innovations Á Major transitions Á Robustness Á Organismic biologyRecently several old questions in evolutionary biology have gained increasing attention: How are evolutionary innovations generated? What is the origin of new

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“…The epidermis of Solenofilomorpha species produces a cuticle-like layer near the tips of microvilli (Doe, 1981;Rieger, 1984;and this study). Such a layer is absent in specimens of Myopea sp.…”

Section: Genus-specific Charactersmentioning

confidence: 99%

Morphology and ultrastructure of the pharynx in Solenofilomorphidae (Acoela)

Todt

Tyler

2006

J. Morphol.

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The homology of pharynges within the mostly pharynx-less Acoela has been a matter of discussion for decades. Here, we analyze the pharynges of three members of the Solenofilomorphidae, Myopea sp. and two species of the genus Solenofilomorpha, by means of light and transmission electron microscopy. Special focus is placed on the ultrastructure of the pharyngeal musculature, epidermis surrounding the mouth, pharyngeal epithelium, and junction with the digestive parenchyma. The main goal of this study was to evaluate the usefulness of certain characters for broader comparisons within the Acoela. Among the three species, characters relating to position of the mouth, presence and elaboration of sphincter muscles, presence of pharyngeal glands, and ultrastructure of epitheliosomes proved to be variously species- and genus-specific. The arrangement of pharyngeal muscles and their connection with body wall musculature, ultrastructure of receptor cells, and morphology of a nonciliated glandular region in the posterior pharynx, in contrast, appear to be characteristic of the family Solenofilomorphidae and thus of predominant interest for comparisons with other acoel families.

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Evolution of the Cuticle in the Lower Eumetazoa

Cited by 35 publications

References 48 publications

The first molluscs ‐ small animals

The first molluscs ‐ small animals

The theory of increasing autonomy in evolution: a proposal for understanding macroevolutionary innovations

Morphology and ultrastructure of the pharynx in Solenofilomorphidae (Acoela)

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