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Peterman DJ, Ritterbush KA. Resurrecting extinct cephalopods with biomimetic robots to explore hydrodynamic stability, maneuverability, and physical constraints on life habits. Sci Rep 2022; 12:11287. [PMID: 35787639 PMCID: PMC9253093 DOI: 10.1038/s41598-022-13006-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/19/2022] [Indexed: 11/29/2022] Open
Abstract
Externally shelled cephalopods with coiled, planispiral conchs were ecologically successful for hundreds of millions of years. These animals displayed remarkable morphological disparity, reflecting comparable differences in physical properties that would have constrained their life habits and ecological roles. To investigate these constraints, self-propelling, neutrally buoyant, biomimetic robots were 3D-printed for four disparate morphologies. These robots were engineered to assume orientations computed from virtual hydrostatic simulations while producing Nautilus-like thrusts. Compressed morphotypes had improved hydrodynamic stability (coasting efficiency) and experienced lower drag while jetting backwards. However, inflated morphotypes had improved maneuverability while rotating about the vertical axis. These differences highlight an inescapable physical tradeoff between hydrodynamic stability and yaw maneuverability, illuminating different functional advantages and life-habit constraints across the cephalopod morphospace. This tradeoff reveals there is no single optimum conch morphology, and elucidates the success and iterative evolution of disparate morphologies through deep time, including non-streamlined forms.
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Affiliation(s)
- David J Peterman
- Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, USA.
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The physical basis of mollusk shell chiral coiling. Proc Natl Acad Sci U S A 2021; 118:2109210118. [PMID: 34810260 DOI: 10.1073/pnas.2109210118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2021] [Indexed: 12/14/2022] Open
Abstract
Snails are model organisms for studying the genetic, molecular, and developmental bases of left-right asymmetry in Bilateria. However, the development of their typical helicospiral shell, present for the last 540 million years in environments as different as the abyss or our gardens, remains poorly understood. Conversely, ammonites typically have a bilaterally symmetric, planispiraly coiled shell, with only 1% of 3,000 genera displaying either a helicospiral or a meandering asymmetric shell. A comparative analysis suggests that the development of chiral shells in these mollusks is different and that, unlike snails, ammonites with asymmetric shells probably had a bilaterally symmetric body diagnostic of cephalopods. We propose a mathematical model for the growth of shells, taking into account the physical interaction during development between the soft mollusk body and its hard shell. Our model shows that a growth mismatch between the secreted shell tube and a bilaterally symmetric body in ammonites can generate mechanical forces that are balanced by a twist of the body, breaking shell symmetry. In gastropods, where a twist is intrinsic to the body, the same model predicts that helicospiral shells are the most likely shell forms. Our model explains a large diversity of forms and shows that, although molluscan shells are incrementally secreted at their opening, the path followed by the shell edge and the resulting form are partly governed by the mechanics of the body inside the shell, a perspective that explains many aspects of their development and evolution.
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Peterman DJ, Ritterbush KA. Vertical escape tactics and movement potential of orthoconic cephalopods. PeerJ 2021; 9:e11797. [PMID: 34316410 PMCID: PMC8288114 DOI: 10.7717/peerj.11797] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/25/2021] [Indexed: 11/23/2022] Open
Abstract
Measuring locomotion tactics available to ancient sea animals can link functional morphology with evolution and ecology over geologic timescales. Externally-shelled cephalopods are particularly important for their central roles in marine trophic exchanges, but most fossil taxa lack sufficient modern analogues for comparison. In particular, phylogenetically diverse cephalopods produced orthoconic conchs (straight shells) repeatedly through time. Persistent re-evolution of this morphotype suggests that it possesses adaptive value. Practical lateral propulsion is ruled out as an adaptive driver among orthoconic cephalopods due to the stable, vertical orientations of taxa lacking sufficient counterweights. However, this constraint grants the possibility of rapid (or at least efficient) vertical propulsion. We experiment with this form of movement using 3D-printed models of Baculites compressus, weighted to mimic hydrostatic properties inferred by virtual models. Furthermore, model buoyancy was manipulated to impart simulated thrust within four independent scenarios (Nautilus-like cruising thrust; a similar thrust scaled by the mantle cavity of Sepia; sustained peak Nautilus-like thrust; and passive, slightly negative buoyancy). Each model was monitored underwater with two submerged cameras as they rose/fell over ~2 m, and their kinematics were computed with 3D motion tracking. Our results demonstrate that orthocones require very low input thrust for high output in movement and velocity. With Nautilus-like peak thrust, the model reaches velocities of 1.2 m/s (2.1 body lengths per second) within one second starting from a static initial condition. While cephalopods with orthoconic conchs likely assumed a variety of life habits, these experiments illuminate some first-order constraints. Low hydrodynamic drag inferred by vertical displacement suggests that vertical migration would incur very low metabolic cost. While these cephalopods likely assumed low energy lifestyles day-to-day, they may have had a fighting chance to escape from larger, faster predators by performing quick, upward dodges. The current experiments suggest that orthocones sacrifice horizontal mobility and maneuverability in exchange for highly streamlined, vertically-stable, upwardly-motile conchs.
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Affiliation(s)
- David J Peterman
- Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, United States
| | - Kathleen A Ritterbush
- Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, United States
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Peterman DJ, Ritterbush KA, Ciampaglio CN, Johnson EH, Inoue S, Mikami T, Linn TJ. Buoyancy control in ammonoid cephalopods refined by complex internal shell architecture. Sci Rep 2021; 11:8055. [PMID: 33850189 PMCID: PMC8044186 DOI: 10.1038/s41598-021-87379-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/26/2021] [Indexed: 02/02/2023] Open
Abstract
The internal architecture of chambered ammonoid conchs profoundly increased in complexity through geologic time, but the adaptive value of these structures is disputed. Specifically, these cephalopods developed fractal-like folds along the edges of their internal divider walls (septa). Traditionally, functional explanations for septal complexity have largely focused on biomechanical stress resistance. However, the impact of these structures on buoyancy manipulation deserves fresh scrutiny. We propose increased septal complexity conveyed comparable shifts in fluid retention capacity within each chamber. We test this interpretation by measuring the liquid retained by septa, and within entire chambers, in several 3D-printed cephalopod shell archetypes, treated with (and without) biomimetic hydrophilic coatings. Results show that surface tension regulates water retention capacity in the chambers, which positively scales with septal complexity and membrane capillarity, and negatively scales with size. A greater capacity for liquid retention in ammonoids may have improved buoyancy regulation, or compensated for mass changes during life. Increased liquid retention in our experiments demonstrate an increase in areas of greater surface tension potential, supporting improved chamber refilling. These findings support interpretations that ammonoids with complex sutures may have had more active buoyancy regulation compared to other groups of ectocochleate cephalopods. Overall, the relationship between septal complexity and liquid retention capacity through surface tension presents a robust yet simple functional explanation for the mechanisms driving this global biotic pattern.
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Affiliation(s)
- David J. Peterman
- grid.223827.e0000 0001 2193 0096Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112 USA
| | - Kathleen A. Ritterbush
- grid.223827.e0000 0001 2193 0096Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112 USA
| | - Charles N. Ciampaglio
- grid.268333.f0000 0004 1936 7937Department of Science, Mathematics, and Engineering, Wright State University (Lake Campus), Celina, OH 45822 USA
| | | | - Shinya Inoue
- grid.39158.360000 0001 2173 7691Hokkaido University Shuma-no-kai, Hokkaido, 060-0817 Japan
| | - Tomoyuki Mikami
- grid.26999.3d0000 0001 2151 536XDepartment of Biological Sciences, University of Tokyo, Tokyo, 113-0032 Japan
| | - Thomas J. Linn
- Division of Paleontology, Frontier Gateway Museum, Glendive, MT 59330 USA
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Hoffmann R, Slattery JS, Kruta I, Linzmeier BJ, Lemanis RE, Mironenko A, Goolaerts S, De Baets K, Peterman DJ, Klug C. Recent advances in heteromorph ammonoid palaeobiology. Biol Rev Camb Philos Soc 2021; 96:576-610. [PMID: 33438316 DOI: 10.1111/brv.12669] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 11/03/2020] [Accepted: 11/06/2020] [Indexed: 01/02/2023]
Abstract
Heteromorphs are ammonoids forming a conch with detached whorls (open coiling) or non-planispiral coiling. Such aberrant forms appeared convergently four times within this extinct group of cephalopods. Since Wiedmann's seminal paper in this journal, the palaeobiology of heteromorphs has advanced substantially. Combining direct evidence from their fossil record, indirect insights from phylogenetic bracketing, and physical as well as virtual models, we reach an improved understanding of heteromorph ammonoid palaeobiology. Their anatomy, buoyancy, locomotion, predators, diet, palaeoecology, and extinction are discussed. Based on phylogenetic bracketing with nautiloids and coleoids, heteromorphs like other ammonoids had 10 arms, a well-developed brain, lens eyes, a buccal mass with a radula and a smaller upper as well as a larger lower jaw, and ammonia in their soft tissue. Heteromorphs likely lacked arm suckers, hooks, tentacles, a hood, and an ink sac. All Cretaceous heteromorphs share an aptychus-type lower jaw with a lamellar calcitic covering. Differences in radular tooth morphology and size in heteromorphs suggest a microphagous diet. Stomach contents of heteromorphs comprise planktic crustaceans, gastropods, and crinoids, suggesting a zooplanktic diet. Forms with a U-shaped body chamber (ancylocone) are regarded as suspension feeders, whereas orthoconic forms additionally might have consumed benthic prey. Heteromorphs could achieve near-neutral buoyancy regardless of conch shape or ontogeny. Orthoconic heteromorphs likely had a vertical orientation, whereas ancylocone heteromorphs had a near-horizontal aperture pointing upwards. Heteromorphs with a U-shaped body chamber are more stable hydrodynamically than modern Nautilus and were unable substantially to modify their orientation by active locomotion, i.e. they had no or limited access to benthic prey at adulthood. Pathologies reported for heteromorphs were likely inflicted by crustaceans, fish, marine reptiles, and other cephalopods. Pathologies on Ptychoceras corroborates an external shell and rejects the endocochleate hypothesis. Devonian, Triassic, and Jurassic heteromorphs had a preference for deep-subtidal to offshore facies but are rare in shallow-subtidal, slope, and bathyal facies. Early Cretaceous heteromorphs preferred deep-subtidal to bathyal facies. Late Cretaceous heteromorphs are common in shallow-subtidal to offshore facies. Oxygen isotope data suggest rapid growth and a demersal habitat for adult Discoscaphites and Baculites. A benthic embryonic stage, planktic hatchlings, and a habitat change after one whorl is proposed for Hoploscaphites. Carbon isotope data indicate that some Baculites lived throughout their lives at cold seeps. Adaptation to a planktic life habit potentially drove selection towards smaller hatchlings, implying high fecundity and an ecological role of the hatchlings as micro- and mesoplankton. The Chicxulub impact at the Cretaceous/Paleogene (K/Pg) boundary 66 million years ago is the likely trigger for the extinction of ammonoids. Ammonoids likely persisted after this event for 40-500 thousand years and are exclusively represented by heteromorphs. The ammonoid extinction is linked to their small hatchling sizes, planktotrophic diets, and higher metabolic rates than in nautilids, which survived the K/Pg mass extinction event.
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Affiliation(s)
- René Hoffmann
- Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Bochum, 44801, Germany
| | - Joshua S Slattery
- School of Geosciences, University of South Florida, 4202 East Fowler Ave., NES 107, Tampa, FL, 33620, U.S.A
| | - Isabelle Kruta
- CR2P - Centre de Recherche en Paléntologie - Paris, UMR 7207, Sorbonne Université-MNHN-CNRS, 4 place Jussieu, case 104, Paris, 75005, France
| | - Benjamin J Linzmeier
- Department of Geoscience, University of Wisconsin - Madison, Madison, WI, 53706, U.S.A
| | - Robert E Lemanis
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, 01307, Germany
| | | | - Stijn Goolaerts
- OD Earth & History of Life, and Scientific Service Heritage, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, Brussels, B-1000, Belgium
| | - Kenneth De Baets
- GeoZentrum Nordbayern, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, 91054, Germany
| | - David J Peterman
- Department of Earth and Environmental Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH, 45435, U.S.A
| | - Christian Klug
- Paläontologisches Institut und Museum, Universität Zürich, Karl-Schmid-Strasse 4, Zürich, 8006, Switzerland
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