A Radicle Solution: Morphology and Biomechanics of the <i>Eucalyptocrinites</i> Root System

Plotnick, Roy E.; Honeycutt, Chris M.E.; Zinga, Anna

doi:10.1017/s2475262200011618

Cited by 2 publications

(3 citation statements)

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“…The dissociation of crowns and holdfasts of scyphocrinoids should not be viewed as unusual, as it is well known in benthic crinoids (e.g., Plotnick et al 2016). The reason for such a dissociation is that these two distinct body parts are affected differentially by biostratinomic processes (e.g., Brett 1981; Brett et al 1997).…”

Section: Discussionmentioning

confidence: 91%

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Bringing planktonic crinoids back to the bottom: Reassessment of the functional role of scyphocrinoid loboliths

et al. 2019

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Living crinoids are exclusively passive suspension feeders and benthic as adults. However, in the past they adapted to a broad range of ecological niches. For instance, the stratigraphically important middle Paleozoic scyphocrinoids are hypothesized to have been planktonic, employing their inferred gas-filled globular, chambered structure at the distal end of the stem, the so-called lobolith, as a buoyancy device with the crinoid calyx suspended below it. Here, we evaluate this hypothesis using evidence from skeletal micromorphology and theoretical biomechanical modeling. Lobolith walls are typically composed of ossicles, which are exclusively composed of constructional labyrinthic stereom. In plates from the distal side of the lobolith, this stereom extends into microperforate stereom layer, forming wavy ridges and spines. No microscale adaptations for preventing gas leaks and/or ingress of water (such as internal and external imperforate stereom layers) are known. Furthermore, theoretical calculations suggest that the scyphocrinoid tow-net mode of feeding would have resulted in small relative velocities between the towed filter and the ambient water, thus making it an ineffective passive filter feeder. We suggest that the lobolith of these crinoids acted as a modified holdfast rather than as a floating buoy. Its globular shape and distally positioned microspines served as adaptations for living in unconsolidated sediments, analogous to iceberg- and snowshoe-like strategies used by some mollusks and brachiopods. Like modern isocrinids, scyphocrinoids could have maintained an upright feeding posture by extending the distal portion of the stalk along the bottom. In this recumbent posture, the distal part of the stalk with the lobolith might have functioned as a drag anchor. As a consequence of the ~3-m-long stem, even with this posture, the benthic scyphocrinoids could have risen to the highest epifaunal tier in the Paleozoic.

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Section: Discussionmentioning

confidence: 91%

“…During their evolutionary history, and especially during the Paleozoic, many crinoids developed a variety of structures at their distal stems identified as adaptations for living on soft substrates (Seilacher and MacClintock 2005; Plotnick et al 2016). In our view, loboliths represent yet another example of such a structure.…”

Section: Discussionmentioning

confidence: 99%

Bringing planktonic crinoids back to the bottom: Reassessment of the functional role of scyphocrinoid loboliths

et al. 2019

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“…The shape of the U. neottioides anchor stolon system could be compared with anchoring holdfasts of some crinoids (see e.g., [ 27 , 28 , 29 ]). However, this is only analogy with the anchoring system between a specialized carnivorous plant and specialized animals.…”

Section: Discussionmentioning

confidence: 99%

Life in the Current: Anatomy and Morphology of Utricularia neottioides

Płachno

Adamec

Świątek

et al. 2020

IJMS

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Rheophytism is extremely rare in the Utricularia genus (there are four strictly rheophytic species out of a total of about 260). Utricularia neottioides is an aquatic rheophytic species exclusively growing attached to bedrocks in the South American streams. Utricularia neottioides was considered to be trap-free by some authors, suggesting that it had given up carnivory due to its specific habitat. Our aim was to compare the anatomy of rheophytic U. neottioides with an aquatic Utricularia species with a typical linear monomorphic shoot from the section Utricularia, U. reflexa, which grows in standing or very slowly streaming African waters. Additionally, we compared the immunodetection of cell wall components of both species. Light microscopy, histochemistry, scanning, and transmission electron microscopy were used to address our aims. In U. neottioides, two organ systems can be distinguished: organs (stolons, inflorescence stalk) which possess sclerenchyma and are thus resistant to water currents, and organs without sclerenchyma (leaf-like shoots), which are submissive to the water streaming/movement. Due to life in the turbulent habitat, U. neottioides evolved specific characters including an anchor system with stolons, which have asymmetric structures, sclerenchyma and they form adhesive trichomes on the ventral side. This anchor stolon system performs additional multiple functions including photosynthesis, nutrient storage, vegetative reproduction. In contrast with typical aquatic Utricularia species from the section Utricularia growing in standing waters, U. neottioides stems have a well-developed sclerenchyma system lacking large gas spaces. Plants produce numerous traps, so they should still be treated as a fully carnivorous plant.

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A Radicle Solution: Morphology and Biomechanics of the Eucalyptocrinites Root System

Cited by 2 publications

References 0 publications

Bringing planktonic crinoids back to the bottom: Reassessment of the functional role of scyphocrinoid loboliths

Bringing planktonic crinoids back to the bottom: Reassessment of the functional role of scyphocrinoid loboliths

Life in the Current: Anatomy and Morphology of Utricularia neottioides

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