Ocular Anatomy, Ganglion Cell Distribution and Retinal Resolution of a Killer Whale(Orcinus orca)

2013 ◽  
Vol 81 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Alla M. Mass ◽  
Alexander Y. Supin ◽  
Andrey V. Abramov ◽  
Lev M. Mukhametov ◽  
Elena I. Rozanova
Keyword(s):  
Ganglion Cell ◽  
Killer Whale ◽  
Orcinus Orca ◽  
Cell Distribution ◽  
Retinal Resolution

Ganglion Cell Distribution and Retinal Resolution in the Florida Manatee, Trichechus Manatus Latirostris

2011 ◽  
Vol 295 (1) ◽  
pp. 177-186 ◽  
Author(s):  
Alla M. Mass ◽  
Darlene R. Ketten ◽  
Daniel K. Odell ◽  
Alexander Ya. Supin
Keyword(s):  
Ganglion Cell ◽  
Cell Distribution ◽  
Florida Manatee ◽  
Trichechus Manatus ◽  
Trichechus Manatus Latirostris ◽  
Retinal Resolution

Morphological estimation of retinal resolution of a killer whale (Orcinus orca)

2012 ◽  
Vol 442 (1) ◽  
pp. 34-37 ◽  
Author(s):  
A. M. Mass ◽  
A. Ya. Supin ◽  
L. M. Mukhametov ◽  
E. I. Rozanova ◽  
A. V. Abramov
Keyword(s):  
Killer Whale ◽  
Orcinus Orca ◽  
Retinal Resolution

scholarly journals Family feud: permanent group splitting in a highly philopatric mammal, the killer whale (Orcinus orca)

2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Eva H. Stredulinsky ◽  
Chris T. Darimont ◽  
Lance Barrett-Lennard ◽  
Graeme M. Ellis ◽  
John K. B. Ford
Keyword(s):  
Killer Whale ◽  
Group Structure ◽  
Group Living ◽  
Orcinus Orca ◽  
Learning Approaches ◽  
Killer Whales ◽  
Internal Factors ◽  
Individual Fitness ◽  
Leadership Experience

Abstract For animals that tend to remain with their natal group rather than individually disperse, group sizes may become too large to benefit individual fitness. In such cases, group splitting (or fission) allows philopatric animals to form more optimal group sizes without sacrificing all familiar social relationships. Although permanent group splitting is observed in many mammals, it occurs relatively infrequently. Here, we use combined generalized modeling and machine learning approaches to provide a comprehensive examination of group splitting in a population of killer whales (Orcinus orca) that occurred over three decades. Fission occurred both along and across maternal lines, where animals dispersed in parallel with their closest maternal kin. Group splitting was more common: (1) in larger natal groups, (2) when the common maternal ancestor was no longer alive, and (3) among groups with greater substructuring. The death of a matriarch did not appear to immediately trigger splitting. Our data suggest intragroup competition for food, leadership experience and kinship are important factors that influence group splitting in this population. Our approach provides a foundation for future studies to examine the dynamics and consequences of matrilineal fission in killer whales and other taxa. Significance statement Group living among mammals often involves long-term social affiliation, strengthened by kinship and cooperative behaviours. As such, changes in group membership may have significant consequences for individuals’ fitness and a population’s genetic structure. Permanent group splitting is a complex and relatively rare phenomenon that has yet to be examined in detail in killer whales. In the context of a growing population, in which offspring of both sexes remain with their mothers for life, we provide the first in-depth examination of group splitting in killer whales, where splitting occurs both along and across maternal lines. We also undertake the first comprehensive assessment of how killer whale intragroup cohesion is influenced by both external and internal factors, including group structure, population and group demography, and resource abundance.

Captive killer whale ( Orcinus orca ) survival

2015 ◽  
Vol 31 (4) ◽  
pp. 1362-1377 ◽  
Author(s):  
John Jett ◽  
Jeffrey Ventre
Keyword(s):  
Killer Whale ◽  
Orcinus Orca

scholarly journals Visual discrimination learning in the killer whale (Orcinus orca)

1971 ◽  
Vol 3 (4) ◽  
pp. 187-188 ◽  
Author(s):  
Don White ◽  
Paul Spong ◽  
Norm Cameron ◽  
John Bradford
Keyword(s):  
Discrimination Learning ◽  
Visual Discrimination ◽  
Killer Whale ◽  
Orcinus Orca ◽  
Visual Discrimination Learning

The retinal ganglion cell distribution and the representation of the visual field in area 17 of the owl monkey, Aotus trivirgatus

1993 ◽  
Vol 10 (5) ◽  
pp. 887-897 ◽  
Author(s):  
L. C. L. Silveira ◽  
V. H. Perry ◽  
E. S. Yamada
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Ganglion Cell ◽  
Cell Density ◽  
Ganglion Cells ◽  
Amacrine Cells ◽  
Temporal Region ◽  
Cell Distribution ◽  
Area 17 ◽  
Displaced Amacrine Cells

AbstractThe distribution of ganglion cells and displaced amacrine cells was determined in whole-mounted Aotus retinae. In contrast to diurnal simians, Aotus has only a rudimentary fovea. Ganglion cell density decreases towards the periphery at approximately the same rate along all meridians, but is 1.2–1.8 times higher in the nasal periphery when compared to temporal region at the same eccentricities. The total number of ganglion cells varied from 421,500 to 508,700. Ganglion cell density peaked at 15,000/mm2 at 0.25 mm dorsal to the fovea. The displaced amacrine cells have a shallow density gradient, their peak density in the central region is about 1500–2000/mm2 and their total number varied from 315,900 to 482,800. Comparison between ganglion cell density and areal cortical magnification factor for the primary visual cortex, area 17, shows that there is not a simple proportional representation of the ganglion cell distribution. There is an overrepresentation of the central 10 deg of the visual field in the visual cortex. The present results for Aotus and the results of a similar analysis of data from other primates indicate that the overrepresentation of the central visual field is a general feature of the visual system of primates.

Development of intentional stranding hunting techniques in killer whale (Orcinus orca) calves at Crozet Archipelago

1995 ◽  
Vol 73 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Christophe Guinet ◽  
Jérome Bouvier
Keyword(s):  
Growth Curve ◽  
Parental Investment ◽  
Killer Whale ◽  
Elephant Seal ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Juvenile Female ◽  
Adult Females ◽  
Social Transfer ◽  
High Degree

This paper describes the trend in the practice of what we interpret to be the "intentional stranding" hunting technique of two juvenile female killer whales (Orcinus orca), A4 and A5, belonging to pod A on the beaches of Possession Island, Crozet Archipelago. Pod A was composed of three adult females, A2, A3, A6, and one adult male, A1. A2 is A4's mother and A3 is A5's mother. The year of birth and thus the probable age of the two juveniles were estimated from their growth curve determined by means of a photogrammetric technique. These observations indicate that at Crozet Archipelago, juvenile killer whales first practiced intentional stranding on their own when they were 4–5 years old. Their first attempt to capture elephant seal pups by means of this technique was observed when they were 5–6 years old. However, 5- to 6-year-old juveniles still needed the assistance of an adult female to return to the water with their prey. This study indicates that learning hunting techniques needs a high degree of skill and requires high parental investment to reduce the associated risk. Furthermore, social transfer, through apprenticeship, is probably one of the mechanisms that enables the high degree of adaptability observed in killer whales.

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