Sublethal injury and shell repair in Upper Mississippian ammonoids

Paleobiology ◽  
1989 ◽  
Vol 15 (4) ◽  
pp. 414-428 ◽  
Author(s):  
Paul N. Bond ◽  
W. Bruce Saunders
Keyword(s):  
Shell Thickness ◽  
Physical Parameters ◽  
Selective Predation ◽  
Chamber Length ◽  
Body Chamber ◽  
Interspecific Differences ◽  
Sublethal Injury ◽  
Shell Damage ◽  
Shell Repair ◽  
Northwest Arkansas

Sublethal injuries recorded in the shells of five Upper Mississippian ammonoid species from the Imo Formation of northwest Arkansas are manifested as repaired shell breaks, which can be categorized as minor, moderate, massive, deep-acute, or as perforations. Overall, 15% of the ammonoids exhibit some form of repaired break. The injuries are distributed as follows: Anthracoceras discus 9%; Fayettevillea bransoni 13%; Fayettevillea friscoense 21%; Rhadinites miseri 24%; Richardsonites mapesi 38%. These figures are substantially lower than in living Nautilus, in which more than one-half of adult specimens exhibit repaired shell breaks. The different frequencies of injuries may reflect species-selective predation, differential abilities to sustain and to repair shell damage, or they may be due to interspecific differences in physical parameters such as shell thickness and body chamber length. The most likely possible perpetrators of the injuries include sharks, other fishes, and cephalopods.

Calculation and simulation of ammonoid hydrostatics

Paleobiology ◽  
1986 ◽  
Vol 12 (1) ◽  
pp. 64-79 ◽  
Author(s):  
W. Bruce Saunders ◽  
Earl A. Shapiro
Keyword(s):  
Shell Thickness ◽  
Close Agreement ◽  
Physical Parameters ◽  
Neutral Buoyancy ◽  
Chamber Length ◽  
Body Chamber ◽  
Individual Variables ◽  
Centers Of Mass ◽  
Neutrally Buoyant ◽  
Shell Geometry

The buoyancy, stability, and orientation of a shelled cephalopod in water are the predictable products of shell geometry, body chamber length, and such physical parameters as shell, tissue, and water densities. Given such physical characteristics as shell geometry, shell, tissue, and water densities, and shell thickness, the hydrostatic characteristics of planispiral shelled cephalopods, including orientation, centers of mass and buoyancy, stability, and neutrally buoyant body chamber length, can be calculated and simulated using microcomputer-based techniques. Individual variables such as geometry, body chamber length, and shell thickness are linked in a calculable manner to orientation, neutral buoyancy, and stability. Living Nautilus provides a means of testing the model and for making hydrostatic comparisons between ammonoids and nautiloids. The close agreement between calculated versus observed body chamber lengths in five species of Mississippian ammonoids shows that neutral buoyancy, and (with one exception) Nautilus-like orientations, were at least feasible for these species.

scholarly journals Research of selected physical indicators of table eggs in the small-scale breedings from the aspect of health safety

10.5219/1357 ◽  
2020 ◽  
Vol 14 ◽  
pp. 893-904
Author(s):  
Mária Angelovičová ◽  
Michal Angelovič ◽  
Lucia Zeleňáková
Keyword(s):  
Equatorial Plane ◽  
Shell Thickness ◽  
Laying Hens ◽  
Small Scale ◽  
Shell Weight ◽  
Egg Weight ◽  
Health Safety ◽  
Free Range ◽  
Shell Damage ◽  
Object Of Study

The purpose of this study was to investigate selected indicators of the table eggs in small-scale breedings, focusing mainly on the eggshell and its contamination and damage. Our object of study was eggs, shell, damage, and contamination of table eggs. Four small-scale breedings were randomly selected in Slovakia. These breeds were alternatively with an outdoor free-range. Laying hens Dominant was bred under conditions small-scale breeds No.1, No. 2 and No. 3 in the 1st laying cycle, and No. 4 in the 2nd laying cycle. Egg weight was balanced in three small-scale breedings. Egg weight was significantly higher in the fourth small-scale breeding, statistically significant (p <0.05) compared to egg weight in the studied 3 small-scale breedings. Shell weight and shell thickness in the equatorial plane of the egg were balanced in three small-scale breedings and in the fourth small-scale breedings were significantly higher, statistically significant (p <0.05). The higher egg weight per breeding is related to the higher laying hens age that was in the 2nd laying cycle compared to laying hens 3 small-scale breedings in the 1st laying cycle. Higher eggshell weight in three farms may be related to improved conditions in breeding hygiene, as confirmed by the results of investigations into contamination and damage to table eggs. These differences may also be related to nutrition.

scholarly journals Mussels repair shell damage despite limitations imposed by ocean acidification

2022 ◽  
Author(s):  
Matthew George ◽  
Michael O'Donnell ◽  
michael concodello ◽  
Emily Carrington
Keyword(s):  
Ocean Acidification ◽  
Stress Responses ◽  
Structural Integrity ◽  
Physiological Stress ◽  
Repair Process ◽  
Elevated Pco2 ◽  
Shell Damage ◽  
Shell Repair ◽  
Inorganic Content ◽  
Field And Laboratory Conditions

Bivalves frequently withstand shell boring attempts by predatory gastropods that result in shell damage that must be quickly repaired to ensure survival. While the processes that underlie larval shell development have been extensively studied within the context of ocean acidification (OA), it remains unclear whether shell repair is impaired by elevated pCO2. To better understand the stereotypical shell repair process, we monitored mussels (Mytilus edulis) with sublethal shell damage within both field and laboratory conditions to characterize the deposition rate, mineral composition, and structural integrity of repaired shell. These results were then compared with a laboratory experiment wherein mussels (Mytilus trossulus) repaired shell damage in one of seven pCO2 treatments (400–2500 µatm). Shell repair proceeded through four distinct stages; shell damage was first covered with an organic film, then mineralized over the course of weeks, acquiring the appearance of nacre after 8 weeks. OA did not impact the ability of mussels to close drill holes, nor the strength or density of the repaired shell after 10-weeks, as measured through mechanical testing and µCT analysis. However, as mussels progressed through each repair stage, significant interactions between pCO2, the length of exposure to treatment conditions, and the strength, inorganic content, and physiological condition of mussels within OA treatments were observed. These results suggest that, while OA may not prevent mussels from repairing shell damage, sustained exposure to elevated pCO2 may induce physiological stress responses that impose energetic constraints on the shell repair process.

First report of a larval shell repair scar on a lingulate brachiopod: evidence of durophagous predation in the Cambrian pelagic realm?

2011 ◽  
Vol 85 (4) ◽  
pp. 695-702 ◽  
Author(s):  
Rebecca L. Freeman ◽  
James F. Miller
Keyword(s):  
Larval Stage ◽  
Abrupt Change ◽  
Larval Shell ◽  
Dorsal Valve ◽  
Shell Material ◽  
Geologic History ◽  
Upper Cambrian ◽  
Injured Area ◽  
Shell Damage ◽  
Shell Repair

A dorsal valve of an Upper Cambrian lingulate brachiopod exhibits a repair scar on the anterior lateral edge of its larval shell. This species is characterized by an abrupt change in ornamentation from larval to postlarval growth. Shell material secreted in the injured area after the damage occurred exhibits ornamentation that is characteristic of postlarval growth, although equivalent growth exhibits characteristics of the larval stage. A break in the edge of the shell is visible, and the growth lines of the larval and postlarval shell were distorted until the broken area was filled in. Damage to the surface of the shell is interpreted to have been caused by the same event. Modern lingulate brachiopod larvae are planktotrophic and are interpreted to have been so throughout their long geologic history. Therefore, an environmental cause of shell damage seems unlikely and the injuries are interpreted to have been caused by an unknown durophagous predator. This specimen offers evidence that lingulate brachiopod larvae were able to survive shell breakage and repair their shells.

scholarly journals Performance of an U-Shaped Oscillating Water Column Wave Energy Converter Device under Oblique Incident Waves

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 137
Author(s):  
Kshma Trivedi ◽  
Santanu Koley ◽  
Kottala Panduranga
Keyword(s):  
Water Column ◽  
Structural Parameters ◽  
Physical Parameters ◽  
Front Wall ◽  
Angle Of Incidence ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Chamber Length ◽  
Wide Range ◽  
Incident Waves

The present study deals with the performance of an U-shaped oscillating water column device under the action of oblique incident waves. To solve the associated boundary value problem, the dual boundary element method (DBEM) is used. Various physical parameters associated with the U-shaped OWC device, such as the radiation susceptance and conductance coefficients, and the hydrodynamic efficiency, are analyzed for a wide range of wave and structural parameters. The study reveals that the resonance in the efficiency curve occurs for smaller values of wavenumber with an increase in chamber length, submergence depth of the front wall and opening duct, and width of the opening duct. It is observed that with appropriate combinations of the angle of incidence and incident wavenumber, more than 90% efficiency in the U-shaped OWC device can be achieved.

Attempted predation and shell repair in Middle and Upper Ordovician gastropods from Sweden

1997 ◽  
Vol 71 (6) ◽  
pp. 1007-1019 ◽  
Author(s):  
J. O. R. Ebbestad ◽  
J. S. Peel
Keyword(s):  
Growth Stages ◽  
Upper Ordovician ◽  
Lower Paleozoic ◽  
Smooth Shell ◽  
Middle Ordovician ◽  
Shell Damage ◽  
Shell Repair ◽  
Late Growth ◽  
Large Sections

Repaired shell injuries are reported in 11 specimens including six genera and eight species of gastropods from the upper Middle Ordovician (Caradoc) Kullsberg Limestone and the Upper Ordovician (Ashgill) Boda Limestone, Siljan district, Sweden. The specimens are of different sizes and morphologies, including one isostrophic, three low-spired, and six moderately high-spired turbinate forms. Single and repeated episodes of shell damage and subsequent repair are preserved, the breaks ranging from simple arcuate or scalloped fractures to removal of large sections of the apertural margin. Both early and late growth stages show damage, but the injuries are usually restricted to only one whorl. No shell repairs were discovered on the 65 more or less complete specimens of the subulitids, although the smooth shell makes observation difficult. Injuries in the Siljan samples are found in both microgastropods and large specimens, but the sample is too small for meaningful quantification. The shell repair frequency is about 7 percent, based on examination of 404 specimens (54 from Kullsberg Limestone and 350 from Boda Limestone). Most of the repaired injuries are attributed to failed predation, adding significantly to the Lower Paleozoic documentation of predation on gastropods. The gastropod shells are morphologically weak by modern standards, but do show some architectural strengthening features such as narrow apertures, collabral or spiral threads, and other ornamentation. The identity of the predator(s) is unknown.

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