scholarly journals Seeing in the deep-sea: visual adaptations in lanternfishes

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160070 ◽  
Author(s):  
Fanny de Busserolles ◽  
N. Justin Marshall
Keyword(s):  
Visual System ◽  
Deep Sea ◽  
Extreme Environment ◽  
Ambient Light ◽  
Body Of Knowledge ◽  
Mesopelagic Zone ◽  
The World ◽  
Dim Light

Ecological and behavioural constraints play a major role in shaping the visual system of different organisms. In the mesopelagic zone of the deep- sea, between 200 and 1000 m, very low intensities of downwelling light remain, creating one of the dimmest habitats in the world. This ambient light is, however, enhanced by a multitude of bioluminescent signals emitted by its inhabitants, but these are generally dim and intermittent. As a result, the visual system of mesopelagic organisms has been pushed to its sensitivity limits in order to function in this extreme environment. This review covers the current body of knowledge on the visual system of one of the most abundant and intensely studied groups of mesopelagic fishes: the lanternfish (Myctophidae). We discuss how the plasticity, performance and novelty of its visual adaptations, compared with other deep-sea fishes, might have contributed to the diversity and abundance of this family. This article is part of the themed issue ‘Vision in dim light’.

scholarly journals The visual ecology of Holocentridae, a nocturnal coral reef fish family with a deep-sea-like multibank retina

2020 ◽  
pp. jeb.233098
Author(s):  
Fanny de Busserolles ◽  
Fabio Cortesi ◽  
Lily Fogg ◽  
Sara M. Stieb ◽  
Martin Luehrmann ◽  
...  
Keyword(s):  
Visual System ◽  
Reef Fish ◽  
Deep Sea ◽  
Colour Vision ◽  
Ganglion Cells ◽  
Light Sensitivity ◽  
Fish Family ◽  
Visual Systems ◽  
Retinal Topography ◽  
Dim Light

The visual systems of teleost fishes usually match their habitats and lifestyles. Since coral reefs are bright and colourful environments, the visual systems of their diurnal inhabitants have been more extensively studied than those of nocturnal species. In order to fill this knowledge gap, we conducted a detailed investigation of the visual system of the nocturnal reef fish family Holocentridae. Results showed that the visual system of holocentrids is well adapted to their nocturnal lifestyle with a rod-dominated retina. Surprisingly, rods in all species were arranged into 6-17 well-defined banks, a feature most commonly found in deep-sea fishes, that may increase the light sensitivity of the eye and/or allow colour discrimination in dim-light. Holocentrids also have the potential for dichromatic colour vision during the day with the presence of at least two spectrally different cone types: single cones expressing the blue-sensitive SWS2A gene, and double cones expressing one or two green-sensitive RH2 genes. Some differences were observed between the two subfamilies, with Holocentrinae (squirrelfish) having a slightly more developed photopic visual system than Myripristinae (soldierfish). Moreover, retinal topography of both ganglion cells and cone photoreceptors showed specific patterns for each cell type, likely highlighting different visual demands at different times of the day, such as feeding. Overall, their well-developed scotopic visual systems and the ease of catching and maintaining holocentrids in aquaria, make them ideal models to investigate teleost dim-light vision and more particularly shed light on the function of the multibank retina and its potential for dim-light colour vision.

scholarly journals The visual ecology of Holocentridae, a nocturnal coral reef fish family with a deep-sea-like multibank retina

2020 ◽  
Author(s):  
Fanny de Busserolles ◽  
Fabio Cortesi ◽  
Lily Fogg ◽  
Sara M. Stieb ◽  
Martin Luerhmann ◽  
...  
Keyword(s):  
Coral Reef ◽  
Visual System ◽  
Reef Fish ◽  
Coral Reef Fish ◽  
Deep Sea ◽  
Colour Vision ◽  
Fish Family ◽  
Visual Systems ◽  
Dim Light ◽  
Dim Light Vision

AbstractThe visual systems of teleost fishes usually match their habitats and lifestyles. Since coral reefs are bright and colourful environments, the visual systems of their diurnal inhabitants have been more extensively studied than those of nocturnal species. In order to fill this knowledge gap, we conducted a detailed investigation of the visual systems of the coral reef fish family Holocentridae (squirrelfish and soldierfish). In addition to their nocturnality, this family is particularly interesting for dim-light vision studies due to its ecological and evolutionary connection to deeper habitats. Results showed that the visual system of holocentrids is well adapted to their nocturnal lifestyle with a rod-dominated retina. Surprisingly, rods in all species were arranged into 6-17 well-defined banks, a feature most commonly found in deep-sea fishes, that may increase the light sensitivity of the eye and/or allow colour discrimination in dim-light. Holocentrids also have the potential for dichromatic colour vision during the day with the presence of at least two spectrally different cone types: single cones expressing the blue-sensitive SWS2A gene, and double cones expressing one or two green-sensitive RH2 genes. Some differences were observed between the two subfamilies, with Holocentrinae having a slightly more developed photopic visual system than Myripristinae. Moreover, retinal topography of both ganglion cells and cone photoreceptors showed specific patterns for each cell type, likely highlighting different visual demands at different times of the day, such as feeding. Overall, their well-developed scotopic visual systems and the ease of catching and maintaining holocentrids in aquaria, make them ideal models to investigate teleost dim-light vision and more particularly shed light on the function of multibank retina and its potential for dim-light colour vision.

Loss of sleep or loss of dark?

2018 ◽  
Author(s):  
Richard G. Stevens
Keyword(s):  
Mood Disorders ◽  
Deep Sea ◽  
Short Distance ◽  
Water Surface ◽  
Ocean Floor ◽  
Physiological Adaptation ◽  
Poor Sleep ◽  
Short Period ◽  
The World ◽  
Night And Day

Before electricity, night was something akin to the deep sea: just as we could not descend much below the water surface, we also could not investigate the night for more than a short distance, and for a short period of time. Things changed with two inventions: the Bathysphere to plumb the ocean floor, and electricity to light the night for sustained exploration. Exploration led to dominance, and night has become indistinguishable from day in many parts of the world. The benefits of electric light are myriad, but so too are the possible detriments of loss of dark at night, including poor sleep, obesity, diabetes, cancer, and mood disorders. Our primordial physiological adaptation to the night and day cycle is being flummoxed by the maladaptive signals coming from electric lighting around the clock. The topic of sleep and health has finally attained scientific respect, but dark and health is not yet fully appreciated.

scholarly journals Ontogenetic adaptations in the visual systems of deep-sea crustaceans

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160071 ◽  
Author(s):  
Tamara M. Frank
Keyword(s):  
Temporal Resolution ◽  
Deep Sea ◽  
Life Histories ◽  
Marine Species ◽  
Light Regime ◽  
Life History Stages ◽  
Visual Systems ◽  
Juvenile Stages ◽  
Dim Light ◽  
Effects Of Temperature

For all visually competent organisms, the driving force behind the adaptation of photoreceptors involves obtaining the best balance of resolution to sensitivity in the prevailing light regime, as an increase in sensitivity often results in a decrease in resolution. A number of marine species have an additional problem to deal with, in that the juvenile stages live in relatively brightly lit shallow (100–200 m depth) waters, whereas the adult stages have daytime depths of more than 600 m, where little downwelling light remains. Here, I present the results of electrophysiological analyses of the temporal resolution and irradiance sensitivity of juvenile and adult stages of two species of ontogenetically migrating crustaceans ( Gnathophausia ingens and Systellaspis debilis ) that must deal with dramatically different light environments and temperatures during their life histories. The results demonstrate that there are significant effects of temperature on temporal resolution, which help to optimize the visual systems of the two life-history stages for their respective light environments. This article is part of the themed issue ‘Vision in dim light’.

scholarly journals Challenges of Home Treatment/Care of COVID-19 Patients in Nigeria: A Public Health Risk and a Huge Deceit of our Time

2021 ◽  
Vol 5 (5) ◽  
pp. 1-17
Author(s):  
Azuonwu O
Keyword(s):  
Daily Basis ◽  
Valuable Data ◽  
X Ray ◽  
Disease Epidemiology ◽  
Body Of Knowledge ◽  
Home Based ◽  
The World ◽  
Analysis And Synthesis ◽  
Foreign Policies ◽  
Copy And Paste

Background: Coronavirus disease-2019 was first discovered in a highly populated city of China in late 2019, and has since spread to most countries of the world, causing several morbidities and mortalities. In the bid to contain the disease and curtail its spread, different countries have instituted several policies, and while these policies may work for some countries, it may not work for others. Nevertheless, the disease has affected over 19 million people globally, killing as many as 700,000. Yet, thousands of persons are still being infected on a daily basis. Aim: To x-ray and evaluate the suitability of home-based treatment/care of COVID-19 patients in Nigeria. Methodology: Peer-reviewed articles revealing information about COVID-19 and its effects globally were sourced from different electronic databases (including WHO, Pub Med, Science Direct, NCDC, etc.), and appraised to extract valuable data and information from them for the purpose of analysis and synthesis of developing robust body of knowledge. Findings: The results obtained from our search include some details about COVID-19 infection, the disease epidemiology, diagnosis, management and guidelines for home-based treatment of COVID-19 patients. Also, discussed in this study are some loopholes in the Nigerian health system and leadership that makes it difficult for foreign policies or strategies (on COVID-19 containment) to be implemented in Nigeria. Conclusion/Recommendation: Differences in lifestyles and cultures among different countries of the world means that there is no one-size-fits-all solution to the problems created by the emergence of the COVID-19 pandemic. Hence, each country is advised to determine which policies best suit the lifestyles and cultures peculiar to her inhabitants. There is literally no room for copy and paste syndrome

Light and the Optical Environment

2014 ◽  
Author(s):  
Thomas W. Cronin ◽  
Sönke Johnsen ◽  
N. Justin Marshall ◽  
Eric J. Warrant
Keyword(s):  
Deep Sea ◽  
Natural Light ◽  
The Sun ◽  
Ambient Light

This chapter explains how humans, and nearly all animals on Earth, witness astonishing variation in their optical environment. Brightness changes by many orders of magnitude each day, and colors also shift dramatically. Those animals that enter forests and especially the water experience even larger changes. Given this, it is surprising that nearly all the natural light on Earth ultimately comes from two sources, the sun and bioluminescence. A final source of light that is potentially relevant to vision is mechanoluminescence. In this process, light is produced by mechanical processes, including deformation (piezoluminescence), fracturing (triboluminescence), and crystallization (crystalloluminescence). The latter two have been suggested as being at least partially responsible for ambient light at deep-sea vents.

Old Norse Mythology as Sacred Narrative

2021 ◽  
pp. 65-102
Author(s):  
John Lindow
Keyword(s):  
Thirteenth Century ◽  
Deep Sea ◽  
Old Norse ◽  
Viking Age ◽  
Chronological Order ◽  
Simple Fact ◽  
The Earth ◽  
The World ◽  
Norse Mythology

This chapter presents a case study of one myth that we have from pictorial sources in the Viking Age, from poems almost certainly composed in the Viking Age, and from thirteenth-century sources, namely the encounter between the god Þórr (Thor) and his cosmic enemy, the World serpent, a beast that encircles the earth, in the deep sea. In this myth, Þórr fishes up the serpent, and depending on the variant, Þórr may or may not kill the serpent. I present and analyze the texts in more or less chronological order, from the older skalds through the Eddic poem Hymiskviða, through Snorri Sturluson in Edda, and compare the texts to the rock carvings that portray the myth. I argue that the issue of the death or survival of the serpent is less important than the simple fact that Þórr had the serpent on his hook.

Ambitionz az a Teacha: understanding Contemporary Rap Music’s Pedagogical Implications

2020 ◽  
Vol 2 (1) ◽  
pp. 31-55
Author(s):  
Asif Wilson ◽  
Daunte Henderson
Keyword(s):  
Media Literacy ◽  
Rap Music ◽  
The Body ◽  
Feminist Scholarship ◽  
Just World ◽  
Pedagogical Tool ◽  
Body Of Knowledge ◽  
The World ◽  
Critical Media

Abstract This case study extends Elligan’s (2000, 2004) Rap Therapy model to explore the pedagogical usefulness of contemporary rap music. Methodologically, the authors borrow the testimonio from Latina Feminist Scholarship, to explore the ways in which young people participating in a summer literacy program analyzed their lives and the world through rap music; how rap music supported their healing; and how rap music was used as a pedagogical tool. Over the course of four months the co-authors of this study created and analyzed 17 co-written testimonios for their generative themes. The authors conclude with a presentation of The (Re) mix—a rap-centered pedagogical framework. The (Re) mix is made up of three, interconnected pillars. One, contemporary rap music (re)tells the experience(s) of the dispossessed. It helps shift the blame for oppression in the world towards the structures of society. Second, contemporary rap music (re)affirms young peoples’ existence. It provides them with an imaginative environment to imagine a more just world. Third, contemporary rap music (re)stores our humanity. It is a tool to name, connect, and move beyond our pain, creating a context for healing as individuals in a collective society. The authors hope that findings of this study empower other educators to infuse contemporary rap music into their pedagogies as a method for students to better read and write the world, adding to the body of knowledge related to critical media literacy.

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