Turning snails into slugs: induced body plan changes and formation of an internal shell

  title={Turning snails into slugs: induced body plan changes and formation of an internal shell},
  author={Raphaela Osterauer and Leonie Marschner and Oliver Betz and Matthias Gerberding and Banthita Sawasdee and Peter Cloetens and Nadine Haus and Bernd Sures and Rita Triebskorn and Heinz-R. K{\"o}hler},
  journal={Evolution \& Development},
SUMMARY The archetypal body plan of conchiferan molluscs is characterized by an external calcareous shell, though internalization of shells has evolved independently in a number of molluscan clades, including gastropod families. In gastropods, the developmental process of torsion is regarded as a hallmark that is associated with a new anatomical configuration. This configuration is present in extant prosobranch gastropod species, which predominantly bear external shells. Here, we show that… 
External and internal shell formation in the ramshorn snail Marisa cornuarietis are extremes in a continuum of gradual variation in development
The formation of internal, external, and intermediate shells is realized within the continuum of a developmental gradient defined by the degree of differential growth of the embryonic mantle edge and shell gland.
TGF-&bgr; signalling is involved in torsion and shell positioning in the giant ramshorn snail Marisa cornuarietis (Gastropoda: Ampullariidae)
This work shows that changes in morphology result from inhibition of both torsion and differential outgrowth of the mantle epithelium and that unhampered TGF-β signalling is required for these processes in the early embryonic development of M. cornuarietis.
An ancient process in a modern mollusc: early development of the shell in Lymnaea stagnalis
A detailed spatial and temporal map of cell movements and differentiation events during early shell development in L. stagnalis is provided to establish a platform for future work aimed at elucidation of the molecular mechanisms and regulatory networks that underlie the evo-devo of the molluscan shell.
Arresting mantle formation and redirecting embryonic shell gland tissue by platinum2+ leads to body plan modifications in Marisa cornuarietis (Gastropoda, Ampullariidae)
This study presents scanning‐electron micrographs and histological sections of platinum2+ (Pt2+)‐treated and untreated M. cornuarietis embryos and compares “normally” developing and “shell‐less” embryos during embryogenesis, to reveal the exact course of events that lead to this body plan shift.
Anatomy and evolution of the first Coleoidea in the Carboniferous
It is suggested that conch internalization happened rather suddenly including early growth stages while the ink sac evolved slightly later, as well as the timing of other important steps in early coleoid evolutionary.
Die Embryonalentwicklung der Paradiesschnecke Marisa cornuarietis (Ampullariidae) unter dem Einfluss von Platin
The archetypal body plan of conchiferan molluscs is characterized by an external calcareous shell, though internalization of shells has evolved independently in a number of molluscan clades,
Enamel Microstructure in Cetacea: a Case Study in Evolutionary Loss of Complexity
Overall, more complex dental structure in extant and extinct cetaceans is associated with smaller, more numerous teeth in taxa that bite or grasp smaller, harder prey with longer, narrower jaws and have more oral processing.
Vestiges of the natural history of development: historical holdovers reveal the dynamic interaction between ontogeny and phylogeny
  • A. Werth
  • Biology
    Evolution: Education and Outreach
  • 2014
Examples of developmental remnants are presented, which often involve circulatory and reproductive alterations, and numerous other retained or reappearing historical holdovers are discussed in ways that reveal the unfolding dynamic interaction between genotype and phenotype.
An extinction event in planktonic Foraminifera preceded by stabilizing selection
Observations indicate that the default reaction of the studied Foraminifera is stabilization, and that stress escalation did not lead to the emergence of adapted forms.


Ontogeny of the Molluscan Shell Field: a Review
In the gastropod, scaphopod, lamellibranch, and cephalopod gastrulae a thickened portion of the posttrochal region is referred to as the embryonic shell field, which invaginates and gives rise to the shell gland, and the shell field descends from the first somatoblasts.
Ontogenetic torsion in two basal gastropods occurs without shell attachments for larval retractor muscles
  • L. Page
  • Biology
    Evolution & development
  • 2002
Results of this study contradict the long‐standing hypothesis, originally proposed by Garstang (1929), that the larval retractor muscles power the morphogenetic movement of ontogenetic torsion in all basal gastropods.
Muscle morphogenesis in primitive gastropods and its relation to torsion
The present investigation shows that during the first phase of torsion the retractor consists of six spindle-shaped cells all attached to the shell apex on the pre-torsional right side, and there is, therefore, evidence in all four genera that the larvae are asymmetrical before torsions begins.
Structure, crystallography, and morphogenesis of the cryptic shell of the terrestrial slug Limax maximus (Mollusca, gastropoda)
The structure and crystallography of the internal shell of the pulmonate gastropod slug Limax maximus were studied at the levels of light and scanning electron microscopy, revealing patterns of shell
Torsion in Patella caerulea (Mollusca, Patellogastropoda): ontogenetic process, timing, and mechanisms
It is argued that paleontological studies dealing with gastropod phylogeny require data other than those based on fossilized attachment sites of adult shell muscles, as well as generally in basal gastropods, to prove torted or untorted conditions in early Paleozoic univalved molluses.
Larval Development and Metamorphosis in Pleurobranchaea maculata, With a Review of Development in the Notaspidea (Opisthobranchia)
Notaspidean larvae are highly derived in terms of the novel traits and the timing of morphogenic events, as morphological similarities may have developed through distinct mechanisms.
Larval Muscle Contraction Fails to Produce Torsion in a Trochoidean Gastropod
It is suggested that torsion may be a loosely constrained developmental process with multiple pathways to the more constrained end result (20, 21) and not refute the monophyly of torsions.
Functional morphology and development of veliger larvae of the European oyster, Ostrea edulis Linné
Study of body and shell in a growth series revealed many structures and patterns of development previously poorly known or unknown: the presence of four ciliary bands on the velum, not three, and the heel-first development of the foot, with medial ciliation of the toe preceding complete ciliation.
Opisthobranchia (Mollusca, Gastropoda) – more than just slimy slugs. Shell reduction and its implications on defence and foraging
According to phylogenetic analyses, the reduction of the shell correlates with the evolution of defensive strategies and had an implication on exploration of new food sources and therefore likely enhanced adaptive radiation of several groups.
Inflated protoconchs and internally dissolved, coiled protoconchs of nudibranch larvae: different developmental trajectories achieve the same morphological result
Examination of protoconch form in eight species of planktotrophic heterobranch larvae found that absence of a post-metamorphic shell is correlated with absence of visceral coiling in this gastropod group, and internal dissolution of the coiled protconch in nudibranchs allows the left digestive gland to uncoil prior to metamorphicShell loss.