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.

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.

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.

Ardmosteges Orchamus New Genus, New Species, in the Early Pennsylvanian of Oklahoma–Possible Ancestor to the Permian Richthofenoid Brachiopods

1996 ◽  
Vol 70 (S46) ◽  
pp. 1-25
Author(s):  
Patrick K. Sutherland
Keyword(s):  
New Species ◽  
Early Development ◽  
New Genus ◽  
Unique Feature ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Shell Material ◽  
Southern Oklahoma ◽  
Upward Growth ◽  
First Time

Ardmosteges orchamus, new genus, new species, from the Early Pennsylvanian Morrowan sequence in southern Oklahoma, is characterized by a well-developed early aulostegid stage, followed by a fully developed richthofenoid stage. It differs markedly from any previously described genus. The nature of the early development, with a rounded aulostegid shell and a prominent interarea in the ventral valve, suggests that it evolved from the Aulostegidae. The most unique feature of Ardmosteges is that it shows for the first time, a documented mechanism for the addition of new shell material above the hinge area in the ventral valve in shells that proceeded to develop a richthofenoid cone. Shell layers were extended posteriorly from the margins of the ventral valve onto the interarea of that valve indicating that the mantle grew onto the hinge area from each side. This irregular and asymmetrical process gradually filled the space above the hinge and was followed by the upward growth of a typical richthofenoid cone. In the proposed development of the Permian richthofenoids from Ardmosteges it is postulated that the characteristic interarea of Ardmosteges was suppressed during extreme development of a distinctly cylindrical cone.Ardmosteges provides the missing link between the Aulostegidae and the Richthofenoidea. Its characters are primitive compared to those of the Permian richthofenoids but it is similar in having a deeply recessed opercular dorsal valve, protective spines in the vestibule above the dorsal valve, and in being attached by rhizoid spines.

scholarly journals Mobergellans from the early Cambrian of Greenland and Labrador: new morphological details and implications for the functional morphology of mobergellans

2017 ◽  
Vol 92 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Christian B. Skovsted ◽  
Timothy P. Topper
Keyword(s):  
Functional Morphology ◽  
Lower Cambrian ◽  
Growth Direction ◽  
Morphological Features ◽  
Larval Shell ◽  
Early Cambrian ◽  
Shell Material ◽  
Muscle Attachment ◽  
Stage 4

AbstractNew morphological features of the mobergellan Discinella micans (Billings, 1871) from the lower Cambrian (Stage 4) of Northeast Greenland and southern Labrador are described. The new features include: (1) the morphology of the larval shell, which is shown to be cap-shaped, subcircular, and with impressions of the internal muscle attachment scars; (2) a range of unusual shell deformations (changes in growth direction resulting in thickened shells, partial detachment of shell laminae and subsequent regrowth, internal projections of shell material increasing the depth of the shell by up to 150%, disturbances and irregular fusion of muscle scars). In addition, we provide new details about the variability in number and shape of the anteriormost internal muscle scars, which often fuse and may vary in number from one to three (resulting in nine to 11 scars in total). Together the new observations provide additional strength for the hypothesis that mobergellan shells represent opercula of an as yet unknown tubular organism.

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.

The Activity of Amoebocytes and of Alkaline Phosphatases during the Regeneration of the Shell in the Snail, Helix aspersa

1951 ◽  
Vol s3-92 (19) ◽  
pp. 307-321
Author(s):  
L. E. WAGGE
Keyword(s):  
Calcium Carbonate ◽  
Digestive Gland ◽  
Shell Growth ◽  
The Body ◽  
Alkaline Phosphatases ◽  
Shell Damage ◽  
Protein Membrane ◽  
Shell Repair ◽  
Feeding Activities ◽  
Snail Helix Aspersa

Experiments show that in Helix aspera amoebocytes repair a damaged shell after transporting calcium carbonate and proteins from other parts of the shell, or from the digestive gland. The mantle is firmly applied to the damaged area and over itexudes fluid rich in amoebocytes. These secrete, and rapidly calcify, a protein membrane. Similar additional calcified membranes give firm protection after 24 hours. The shell serves as a reservoir of calcium and protein, invaluable to a terrestrial gastropod. Amoebocytes can carry calcium back to the body. Extensive shell damage is repairable provided enough reserves remain: a snail cannot rebuild an entirely new shell. Thickening occurs whenever calcium and protein are available. Shell growth, however, initiated by the secretion of the periostracum, exclusively formed by the mantle skirt, happens only in conjunction with body growth. Provided feeding activities are normal, alkaline phosphatases are abundant during shell repair, especially around digestive gland lime cells. Shell repair and digestion are closely associated. Amoebocytes, ineffective in an active, starved snail, can repeatedly repair damaged shell when a snail feeds, if only on filter paper: for once stimulated ample calcium and proteins are available for them in the shell.

The early development of antenna and antennal sensilla in the noctuid moth, Agrotis segetum (Insecta: Lepidoptera)

1990 ◽  
Vol 48 (3) ◽  
pp. 502-503
Author(s):  
Eric Hallberg ◽  
Lina Hansén
Keyword(s):  
Cell Death ◽  
Stem Cell ◽  
Early Development ◽  
Larval Stage ◽  
Pupal Stage ◽  
Agrotis Segetum ◽  
Antennal Sensilla ◽  
Noctuid Moth ◽  
Standard Procedures

The antennal rudiments in lepidopterous insects are present as disks during the larval stage. The tubular double-walled antennal disk is present beneath the larval antenna, and its inner layer gives rise to the adult antenna during the pupal stage. The sensilla develop from a cluster of cells that are derived from one stem cell, which gives rise to both sensory and enveloping cells. During the morphogenesis of the sensillum these cells undergo major transformations, including cell death. In the moth Agrotis segetum the pupal stage lasts about 14 days (temperature, 25°C). The antennae, clearly seen from the exterior, were dissected and fixed according to standard procedures (3 % glutaraldehyde in 0.15 M cacaodylate buffer, followed by 1 % osmiumtetroxide in the same buffer). Pupae from day 1 to day 8, of both sexes were studied.

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