The Composition of Tidally Deposited Growth Lines in the Shell of the Edible Cockle, Cerastoderma Edule

Author(s):  
Margaret R. Deith

The shells of marine invertebrates grow incrementally (Wilbur, 1972). When a section of shell is observed under the microscope, the increments are often visible, separated by fine lines (Fig. 1). Studies of these phenomena have focused chiefly on the periodicity of increment and growth-line formation, principally because of its geological or archaeological application as a ‘biological clock’ (e.g. Wells, 1963; Koike, 1973).

1984 ◽  
Vol 62 (12) ◽  
pp. 2495-2504 ◽  
Author(s):  
Margaret E. Day

Growth records retained in the shell of Lampsilis radiata radiata and shell ultrastructure were examined in a population from Lake Champlain, Vermont, U.S.A. Maximum size was 75 mm as measured from the umbo to the farthest margin. Ages were obtained by counting annual bands, and growth plots were constructed. By knowing the amount grown by individuals of the same age in the same year, the years 1975 and 1977 were identified as poor for growth of younger individuals. Light micrographs of shell thin sections showed macroscopic annual lines, and microscopic and ultrastructural lines. Ultrastructural lines were visible within macroscopic lines. Scanning electron micrographs of etched sections clarified the light micrographs and allowed recognition of two damage-response structures embedded within the nacreous layer in the umbonal region: adventitious conchiolin and prismatic crystals. Theories of growth line formation are presented. Shell growth appears to follow an alternating cycle of protein deposition as organic matrices followed by CaCO3 secretion into the matrices. The Lutz–Rhoads theory of growth line formation, based on alternating periods of aerobic and anaerobic metabolism, was examined in detail and found unsuitable for this species.


Author(s):  
Pedro Miguel Callapez ◽  
Ricardo Pimentel

Resumo O menir de Padrão 1 constitui um dos monumentos mais representativos do núcleo megalítico de Sagres - Vila do Bispo, localizado no extremo sudoeste do Algarve (sul de Portugal). Nas intervenções arqueológicas de que foi alvo em 1984 e 1994, sob direção de Mário Varela Gomes, foi efetuada uma amostragem exaustiva de concentrações de restos esqueléticos de invertebrados marinhos presentes num contexto de ocupação do Neolítico antigo. Considerando a sua importância para o entendimento das estratégias de subsistência, economia alimentar e práticas culturais durante este intervalo marcante da Pré-história recente, procedeu-se ao seu estudo zooarqueológico. Contabilizou-se um número mínimo de 1496 indivíduos pertencentes a 25 espécies de moluscos bivalves e gastrópodes, três de crustáceos e uma de anelídeo poliqueta. A sua composição, abundância relativa e análise paleoecológica sugerem práticas locais de subsistência, ligadas à exploração oportunista de espécies comestíveis. A recoleção seletiva incidiu em áreas rochosas expostas do litoral próximo (Patella depressa, P. ulyssiponensis, Mytilus galloprovincialis, Perna perna, Stramonita haemastoma, Pollicipes pollicipes), mas também em meio estuarino ou lagunar hoje já desaparecido (Cerastoderma edule, Ruditapes decussatus). A associação presente, com destaque para P. perna, S. haemastoma e Siphonaria pectinata, é compatível com o ótimo climático holocénico, durante o qual espécies mediterrânicas e oeste-africanas ampliaram a sua área de repartição biogeográfica para norte, até à costa portuguesa. Destaca-se, ainda, a ocorrência de P. perna, dado o seu possível carácter inédito em contextos pré-históricos portugueses. Resumen El menhir de Padrão 1 constituye uno de los monumentos más representativos del núcleo megalítico de Sagres - Vila do Bispo, ubicado en el extremo suroeste del Algarve (sur de Portugal). En las intervenciones arqueológicas de que fue objeto en 1984 y 1994, dirigidas por Mário Varela Gomes, se efectuó un muestreo exhaustivo de concentraciones de restos esqueléticos de invertebrados marinos en un contexto de ocupación del Neolítico antiguo. Considerando su importancia para el entendimiento de las estrategias de subsistencia, economía alimentaria y prácticas culturales durante este intervalo importante de la Prehistoria reciente, se procedió a su estudio zooarqueológico. Se contabilizó un número mínimo de 1496 individuos pertenecientes a 25 especies de moluscos bivalvos y gasterópodos, tres de crustáceos y una de gusano poliqueto. Su composición, abundancia relativa y análisis paleoecológico sugieren prácticas locales de subsistencia, ligadas a la explotación oportunista de especies comestibles. La recolección selectiva se centró en áreas rocosas expuestas del litoral próximo (Patella depressa, P. ulyssiponensis, Mytilus galloprovincialis, Perna perna, Stramonita haemastoma, Pollicipes pollicipes), pero también en un medio estuarino o lagunar hoy ya desaparecido (Cerastoderma edule, Ruditapes decussatus). Esta asociación, especialmente P. perna, S. haemastoma y Siphonaria pectinata, es compatible con el óptimo climático del Holoceno, durante el cual las especies del Mediterráneo y de África Occidental extendieron su área de distribución biogeográfica hacia al norte, hasta la costa portuguesa. Se destaca también la presencia de P. perna, dada su posible primera cita en contextos prehistóricos portugueses. Abstract The menhir of Padrão 1 has been known as one of the most representative monuments from the megalithic nucleus of Sagres - Vila do Bispo, in the southwest end of Algarve (South of Portugal). During two archaeological interventions made in 1984 and 1994, under direction of Mário Varela Gomes, an exhaustive sampling of concentrations of skeletal remains of marine invertebrates from an early Neolithic settlement context was made. Considering its importance to understand subsistence strategies, food economy and cultural practices during this important interval of recent Prehistory, the zooarchaeological study of this assemblage was carried out. A minimal number of 1496 individuals was counted, including 25 species of bivalve and gastropod mollusks, three of crustaceans and one of polychaete worm. Its composition, relative abundance and paleoecologic analysis suggest local strategies of subsistence based on the opportunistic exploitation of edible species. The selective recollection was more effective on intertidal rocky shores available in the proximity (Patella intermedia, P. ulyssiponensis, Mytilus galloprovincialis, Perna perna, Stramonita haemastoma, Pollicipes pollicipes), but also made from a possible estuarine or lagoonal environment already disappeared (Cerastoderma edule, Ruditapes decussatus). The faunal association, with emphasis on P. perna, S. haemastoma and Siphonaria pectinata, is compatible with the Holocene climatic optimum, when several Mediterranean and West-African species have extended their biogeographic ranges northwards, till the Portuguese coast. The mytilid P. perna also stands out, as the first occurrence of this species in Portuguese Pre-historic contexts.


Science ◽  
1977 ◽  
Vol 198 (4323) ◽  
pp. 1222-1227 ◽  
Author(s):  
R. A. Lutz ◽  
D. C. Rhoads
Keyword(s):  

2020 ◽  
Vol 237 (2) ◽  
pp. 367-378 ◽  
Author(s):  
Amanda M. Papakyrikos ◽  
Manish Arora ◽  
Christine Austin ◽  
Julia C. Boughner ◽  
Terence D. Capellini ◽  
...  

Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.


Author(s):  
M. Sato ◽  
Y. Ogawa ◽  
M. Sasaki ◽  
T. Matsuo

A virgin female of the noctuid moth, a kind of noctuidae that eats cucumis, etc. performs calling at a fixed time of each day, depending on the length of a day. The photoreceptors that induce this calling are located around the neurosecretory cells (NSC) in the central portion of the protocerebrum. Besides, it is considered that the female’s biological clock is located also in the cerebral lobe. In order to elucidate the calling and the function of the biological clock, it is necessary to clarify the basic structure of the brain. The observation results of 12 or 30 day-old noctuid moths showed that their brains are basically composed of an outer and an inner portion-neural lamella (about 2.5 μm) of collagen fibril and perineurium cells. Furthermore, nerve cells surround the cerebral lobes, in which NSCs, mushroom bodies, and central nerve cells, etc. are observed. The NSCs are large-sized (20 to 30 μm dia.) cells, which are located in the pons intercerebralis of the head section and at the rear of the mushroom body (two each on the right and left). Furthermore, the cells were classified into two types: one having many free ribosoms 15 to 20 nm in dia. and the other having granules 150 to 350 nm in dia. (Fig. 1).


2006 ◽  
Vol 19 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Myriam Juda ◽  
Mirjam Münch ◽  
Anna Wirz-Justice ◽  
Martha Merrow ◽  
Till Roenneberg

Abstract: Among many other changes, older age is characterized by advanced sleep-wake cycles, changes in the amplitude of various circadian rhythms, as well as reduced entrainment to zeitgebers. These features reveal themselves through early morning awakenings, sleep difficulties at night, and a re-emergence of daytime napping. This review summarizes the observations concerning the biological clock and sleep in the elderly and discusses the documented and theoretical considerations behind these age-related behavioral changes, especially with respect to circadian biology.


Planta Medica ◽  
2013 ◽  
Vol 79 (10) ◽  
Author(s):  
DTA Youssef ◽  
LA Shaala ◽  
F Al-Jamali ◽  
E Schmidt

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