Age, Growth, and Maturity of Bottlenosed Dolphin (Tursiops truncatus) from Northeast Florida

1973 ◽  
Vol 30 (7) ◽  
pp. 1009-1011 ◽  
Author(s):  
D. E. Sergeant ◽  
David K. Caldwell ◽  
Melba C. Caldwell
Keyword(s):  
Tursiops Truncatus ◽  
Accumulation Rate ◽  
Age Determination ◽  
Growth Layer ◽  
Translucent Zone ◽  
Bottlenosed Dolphin ◽  
Males And Females ◽  
Absolute Age

It is confirmed that one growth layer consisting of one opaque and one translucent zone is laid down annually in the dentine of the teeth of bottlenosed dolphin (Tursiops truncatus), allowing absolute age determination, although the seasonal sequence of dentine deposition is not yet clear. On this basis females from northeast Florida were found to mature at about 12 years and males at 13 years, both sexes living to about 25 years of age. Females accumulated up to 14 corpora albicantia in the ovaries, indicating an accumulation rate of about one per annum. Birth occurred at 100-cm length. Males and females matured at about 245- and 235-cm length, respectively, and attained asymptotic lengths of about 270 and 250 cm.

scholarly journals Validation of Age Estimation in the Harp Seal, Phoca groenlandica, Using Dentinal Annuli

1983 ◽  
Vol 40 (9) ◽  
pp. 1430-1441 ◽  
Author(s):  
W. D. Bowen ◽  
D. E. Sergeant ◽  
T. Øritsland
Keyword(s):  
Outer Layer ◽  
Age Estimation ◽  
Transverse Section ◽  
Age Determination ◽  
Middle Layer ◽  
Harp Seal ◽  
Growth Layer ◽  
Phoca Groenlandica ◽  
Incremental Growth ◽  
Absolute Age

We investigated the validity and accuracy of age estimation in harp seals, Phoca groenlandica, using a sample of 155 known-age teeth from seals age 3 mo to 10 yr. Under transmitted light, transverse sections of harp seal canine teeth showed distinct incremental growth layers (IGLs) in the dentine. The first growth-layer group (GLG), representing Ist-year growth, consists of two IGLs: an outer layer of opaque dentine, bounded by the neonatal line, and an inner layer of translucent dentine. Subsequent GLGs, each representing 1 yr of growth, generally consist of three IGLs: an outer layer of interglobular dentine deposited during the annual molt in April, a middle layer of opaque dentine formed during the northward spring migration (May–June), and an inner layer of translucent dentine formed from July to March. We show that dentinal GLGs can be used to estimate the absolute age of harp seals. The accuracy of the method decreases with age. Only 72.4% of estimates of 0-group seals were correct using only transverse sections. These errors were virtually eliminated (99.0% correct age determination) when the tooth root was examined. Based on a single examination of a transverse section, the probabilities of correctly estimating age are 0.983, 0.889, 0.817, and 0.553 at ages 1, 2, 3, and 4 + yr, respectively, when clearly inaccurate tag-tooth associations are omitted. The respective probabilities are only slightly higher when age is based on the average of five blind readings, being 1.0, 0.889, 0.833, and 0.625. Beyond age 3 yr, existing data are insufficient to estimate reliably the accuracy of age determined by counting GLGs.

Age determination of harbour porpoise, Phocoena phocoena (L.), in the western North Atlantic

1977 ◽  
Vol 55 (1) ◽  
pp. 18-30 ◽  
Author(s):  
D. E. Gaskin ◽  
B. A. Blair
Keyword(s):  
North Atlantic ◽  
Age Determination ◽  
Simple Relationship ◽  
Phocoena Phocoena ◽  
Progressive Reduction ◽  
Opaque Zone ◽  
Translucent Zone ◽  
Males And Females ◽  
Calving Season

Age, based on analysis of dentinal growth layers, was determined in a sample of 121 harbour porpoises, Phocoena phocoena (L.), from western North Atlantic waters. One growth layer, consisting of a thick opaque zone and a relatively thin translucent zone, is deposited each year.Mean thicknesses of opaque and translucent zones in males and females were 347 μm, 114 μm, 432 μm, and 125 μm, respectively. Significant reduction in thicknesses of growth layers with age was found in both sexes, the major contribution in both cases being progressive reduction in thickness of the opaque zones. Translucent-zone thickness decreased with age in males, but significantly increased in thickness in females. Formation of the opaque zone occurs from June through February, and formation of the translucent zone from January to early September. This overlap is attributed to the protracted calving season of this population, and precludes any simple relationship between food supply and zonation, as proposed by others. Age–length relationships based on numbers of dentinal layers were calculated for males and females using regression analysis. Best fits of body length (b) against age (expressed by completed dentinal layers) (d) were obtained from the curvilinear equations: d = [b/(−1.30b + 209.35)] −1 for males, and d = [b/(−0.84b + 156.15)] −1 for females.

Variability of Dentin Deposits in Tursiops truncatus

1980 ◽  
Vol 37 (4) ◽  
pp. 712-716 ◽  
Author(s):  
Clifford A. Hui
Keyword(s):  
Tursiops Truncatus ◽  
Age Determination ◽  
Growth Layer ◽  
Posterior Teeth ◽  
Annual Cycles ◽  
Left And Right ◽  
Layer Groups

Dentin is deposited in approximately annual cycles in Tursiops truncatus for at least the first 11 yr. There were no consistent differences in the dentinal layer count between the left and right sides nor between the mandible and maxilla in the teeth of nine animals studied. The posterior teeth, however, have a greater number of growth layer groups (GLGs). The differences in the number of GLGs among teeth of the same individual increase unpredictably when there are more than about 15 GLGs in the posterior teeth. Only minimal age may be determined using dentinal counts.Key words: age determination, dentin, dolphins, odontocetes, teeth, Tursiops

scholarly journals A note on the age at sexual maturity of humpback whales

2020 ◽  
pp. 71-73
Author(s):  
Peter B. Best
Keyword(s):  
Sexual Maturity ◽  
Gulf Of Maine ◽  
Accumulation Rate ◽  
Age Determination ◽  
Biological Data ◽  
Humpback Whales ◽  
Natural Mortality ◽  
Growth Layer ◽  
Younger Age ◽  
Layer Groups

The conclusion of researchers in the 1950s that humpback whales reached sexual maturity at about age five was largely influenced by their interpretation of baleen tracings, and to achieve consistency with these tracings the accumulation rate of ear plug laminations (growth layer groups: GLGs) was assumed to be two per year. However, ovulation and natural mortality rates calculated by these researchers under the same assumption produced estimates that are difficult to reconcile with other biological data or with more recent estimates using individual re-sighting data. Such disparities are reduced or disappear when an annual accumulation rate is used, in which case their ear plug data would have indicated a mean age at sexual maturity of 9–11 years. Recent estimates of the age of female humpback whales at first calving using longitudinal studies of photoidentified individuals have produced conflicting results, some (from southeastern Alaska) being compatible with the earlier age-determination studies, others (from the Gulf of Maine) suggesting a much younger age.

scholarly journals Growth of the skull of the bottlenose dolphin, Tursiops truncatus, in the Southwest Atlantic Ocean

10.5597/00229 ◽  
2017 ◽  
Vol 11 (1-2) ◽  
pp. 199-211 ◽  
Author(s):  
André Silva Barreto
Keyword(s):  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Growth Equation ◽  
Growth Layer ◽  
Southwest Atlantic ◽  
Development Patterns ◽  
Skull Measurements ◽  
The One ◽  
Layer Groups ◽  
Mature Size

Defining the age of attainment of physical maturity is important for many studies, including identification of stocks, populations or species. In order to identify the age when the skull of the bottlenose dolphin, Tursiops truncatus, reaches maturity, skulls of fifty-three specimens found stranded along the coasts of southern Brazil, Uruguay and northern Argentina (27o35’S, 48o34’W-36o49’S, 55o19’W) were analyzed. Sixty skull measurements were taken to compare the growth rate of the different functional apparatuses. Age was estimated by counts of growth layer groups in the dentine of decalcified, stained longitudinal sections of teeth. Von Bertalanffy’s equation was applied to assess the growth and determine the age at maturity of each apparatus. Generally the maturation of skull starts at age two and stabilizes at age five, and the age of reaching the mature size varies amongst different characters. The braincase is the most precocious apparatus, while the feeding is the one that last stabilizes. The development patterns observed for the hearing, vision and breathing apparatuses were similar. Statistic analysis revealed significant differences among the ages at maturity, but not for von Bertalanffy’s growth equation parameters for each functional apparatus. For the studied population it is suggested that skulls can be considered mature in animals with more than five years. 

scholarly journals Spermatozoa of the Atlantic bottlenosed dolphin, Tursiops truncatus

Reproduction ◽  
1981 ◽  
Vol 63 (2) ◽  
pp. 509-514 ◽  
Author(s):  
A. D. Fleming ◽  
R. Yanagimachi ◽  
H. Yanagimachi
Keyword(s):  
Tursiops Truncatus ◽  
Bottlenosed Dolphin

Chemical Methods

1998 ◽  
Author(s):  
Norman Herz ◽  
Ervan G. Garrison
Keyword(s):  
Chemical Change ◽  
Age Determination ◽  
Chemical Processes ◽  
Chemical Methods ◽  
Amino Acid Racemization ◽  
Singular Event ◽  
Archaeological Materials ◽  
History Of ◽  
Absolute Age ◽  
Chemical Dating

Time is nature's way of keeping everything from happening at once" (anonymous). Time is a continuum—we sense this continuum as a succession of events. In archaeological matters it is one of the most salient attributes. To determine time accurately the archaeologist must rely on modern dating techniques. Age determination by chemical methods relies on the constancy or predictability of rates of chemical processes. For instance the oxidation of iron—rust—could be used for dating purposes if one could determine a chemical rate, in this case that of oxidation, that applied to more than the singular event. Unfortunately, the rate of the oxidation of iron is highly variable, being affected by temperature, available moisture, and the particular type of iron (mild, cast, stainless, etc.). Another common chemical change is the patination of certain types of glass. Yet here, too, the process is highly variable, making dating impractical. Still, there have been attempts to use patination and rock "varnish" for archaeological dating, as we shall see. In the main, chemical dating is used to determine relative ages since absolute ages require calibration for each sample and its find site using independent dating measures such as radiometric or dendrochronological techniques. We shall first discuss the relative techniques based on the uptake or decrease in fluorine, uranium, and nitrogen found in bone. This is most appropriate because these chemical techniques played a key role in unmasking one of the most famous frauds in the history of science: Piltdown Man. Next we shall examine the two most accepted chemical processes utilized in absolute age determination, which are based, respectively, on amino acid racemization and obsidian hydration. Finally, we shall examine a few techniques that show some promise for the dating of archaeological materials or deposits, such as those using patination ("varnish") and cation ratios. Our points of reference are those events we view as, in some sense, marking a change in the state of things. Stylistic or formal change in an archaeological facies can be a chronological landmark for the archaeologist and allows us to divide the continuum of time into discrete segments or phases.

scholarly journals Dynamical Age Determination of Open Clusters

1980 ◽  
Vol 85 ◽  
pp. 221-222
Author(s):  
M. Buchholz ◽  
Th. Schmidt-Kaler
Keyword(s):  
Age Determination ◽  
Dynamical Theory ◽  
Distribution Functions ◽  
Open Clusters ◽  
Kolmogorov Smirnov ◽  
The Difference ◽  
Absolute Age ◽  
Image Position ◽  
Smirnov Test

The radial mass distribution (obtained by counting stars in strips) of the real cluster is compared successively to the distribution functions of a simulated cluster of 100 stars, each of which corresponds to a certain dynamical age, Tdyn, The value of Tdyn, belonging to the function most similar to the observed one is taken to be the dynamical age of the cluster. The radius is given in units of R1/2 (sphere containing half of the total mass); this unit is nearly time-independent. The difference between the distribution functions is measured by the maximum Δmax of the Kolmogorov-Smirnov test which is free from assumptions on the form of the distributions. The minimum in the plot Δmax vs Tdyn, indicates the age of the cluster. It is then converted into an absolute age, Tabs (in years), by The error due to the dynamical theory (limited number of distribution functions, etc.) is estimated at 12%, the error due to the uncertainty of diameter and mass of the cluster is about 30%. Unreliable results were obtained in case of strongly inhomogeneous reddening of the cluster. As an example, the plot of the test values for NGC 457 is given in Figure 1.

Measuring recovery from temporary threshold shifts with evoked auditory potentials in the bottlenosed dolphin Tursiops truncatus

2001 ◽  
Vol 110 (5) ◽  
pp. 2721-2721 ◽  
Author(s):  
Paul E Nachtigall ◽  
Alexendre Supin ◽  
Jeffrey L. Pawloski ◽  
Whitlow W. L. Au
Keyword(s):  
Tursiops Truncatus ◽  
Bottlenosed Dolphin
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