Morphology and deep metazoan phylogeny

Schmidt‐Rhaesa, Andreas

doi:10.1007/s00435-009-0096-6

Cited by 6 publications

(2 citation statements)

References 12 publications

(13 reference statements)

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“…In its overall arrangement, the regularly spaced and highly concentrated array of diverse sensory cells at the front end of the planula is reminiscent of the sensory neuronal arrays of simple bilaterians (Raikova et al, 1998;Gaerber et al, 2007;Kotikova and Raikova, 2008;Schmidt-Rhaesa, 2009). Moreover, the ordered array of neural processes in this plexus has morphological features that are also found in the central neuropiles of bilaterian ganglia (Meinertzhagen, 2010).…”

Section: Evolutionary Considerationsmentioning

confidence: 99%

Complex neural architecture in the diploblastic larva of Clava multicornis (Hydrozoa, Cnidaria)

Piraino

Zega

Benedetto

et al. 2011

J of Comparative Neurology

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The organization of the cnidarian nervous system has been widely documented in polyps and medusae, but little is known about the nervous system of planula larvae, which give rise to adult forms after settling and metamorphosis. We describe histological and cytological features of the nervous system in planulae of the hydrozoan Clava multicornis. These planulae do not swim freely in the water column but rather crawl on the substrate by means of directional, coordinated ciliary movement coupled to lateral muscular bending movements associated with positive phototaxis. Histological analysis shows pronounced anteroposterior regionalization of the planula's nervous system, with different neural cell types highly concentrated at the anterior pole. Transmission electron microscopy of planulae shows the nervous system to be unusually complex, with a large, orderly array of sensory cells at the anterior pole. In the anterior half of the planula, the basiectodermal plexus of neurites forms an extensive orthogonal network, whereas more posteriorly neurites extend longitudinally along the body axis. Additional levels of nervous system complexity are uncovered by neuropeptide-specific immunocytochemistry, which reveals distinct neural subsets having specific molecular phenotypes. Together these observations imply that the nervous system of the planula of Clava multicornis manifests a remarkable level of histological, cytological, and functional organization, the features of which may be reminiscent of those present in early bilaterian animals.

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Section: Evolutionary Considerationsmentioning

confidence: 99%

Complex neural architecture in the diploblastic larva of Clava multicornis (Hydrozoa, Cnidaria)

Piraino

Zega

Benedetto

et al. 2011

J of Comparative Neurology

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“…Even though we have access to comprehensive and robust molecular phylogenies, the inference of evolutionary histories depends on fine‐scale, semaphoront‐rich morphological databases (and also behavioral, biochemical, etc.). The explanatory power behind phylogenetic trees is only feasible if morphological data are combined, so that the evolutionary changes become evident (Schmidt‐Rhaesa, 2009). As stated by Peters et al.…”

Section: The Haeckelian Shortfall and Dna‐based Systematicsmentioning

confidence: 99%

The Haeckelian shortfall or the tale of the missing semaphoronts

Faria

Pie

Salles

et al. 2020

J. Zool. Syst. Evol. Res.

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When faced with the daunting and exciting task of studying biodiversity, one must necessarily come to terms with a few challenging knowledge gaps, the so‐called biodiversity shortfalls. Given that biodiversity is inherently multidimensional, it seems rather natural to admit that hitherto unrecognized shortfalls, on other distinct aspects of biodiversity, should be considered. Here, we introduce the Haeckelian shortfall, which has as its nexus organismal ontogeny, and refers to the relative scarcity of knowledge about the distinct semaphoronts of a substantial fraction of all known species. The Haeckelian shortfall has a profound relevance on the matter of total evidence, in the context of systematics, besides several indirect effects on the other shortfalls, as they all are intimately interconnected. The importance of studying distinct semaphoronts is crystal clear: Besides the purest and most descriptive access to the ontogeny of species (the idiographic aspect), assessing those semaphoronts will certainly promote the advancement of relevant nomothetic knowledge, contributing to an increasingly meaningful eco–evo–devo. Overcoming the Haeckelian shortfall is certainly a major challenge in our task of knowing and preserving biodiversity.

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Application of magnetic resonance imaging in zoology

et al. 2011

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Magnetic resonance imaging (MRI) is a noninvasive imaging technique that today constitutes one of the main pillars of preclinical and clinical imaging. MRI’s capacity to depict soft tissue in whole specimens ex vivo as well as in vivo, achievable voxel resolutions well below (100 μm)3, and the absence of ionizing radiation have resulted in the broad application of this technique both in human diagnostics and studies involving small animal model organisms. Unfortunately, MRI systems are expensive devices and have so far only sporadically been used to resolve questions in zoology and in particular in zoomorphology. However, the results from two recent studies involving systematic scanning of representative species from a vertebrate group (fishes) as well as an invertebrate taxon (sea urchins) suggest that MRI could in fact be used more widely in zoology. Using novel image data derived from representative species of numerous higher metazoan clades in combination with a comprehensive literature survey, we review and evaluate the potential of MRI for systematic taxon scanning. According to our results, numerous animal groups are suitable for systematic MRI scanning, among them various cnidarian and arthropod taxa, brachiopods, various molluscan taxa, echinoderms, as well as all vertebrate clades. However, various phyla in their entirety cannot be considered suitable for this approach mainly due to their small size (e.g., Kinorhyncha) or their unfavorable shape (e.g., Nematomorpha), while other taxa are prone to produce artifacts associated either with their biology (e.g., Echiura) or their anatomy (e.g., Polyplacophora). In order to initiate further uses of MRI in zoology, we outline the principles underlying various applications of this technique such as the use of contrast agents, in vivo MRI, functional MRI, as well as magnetic resonance spectroscopy. Finally, we discuss how future technical developments might shape the use of MRI for the study of zoological specimens

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Morphology and deep metazoan phylogeny

Cited by 6 publications

References 12 publications

Complex neural architecture in the diploblastic larva of Clava multicornis (Hydrozoa, Cnidaria)

Complex neural architecture in the diploblastic larva of Clava multicornis (Hydrozoa, Cnidaria)

The Haeckelian shortfall or the tale of the missing semaphoronts

Application of magnetic resonance imaging in zoology

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