Hormones Regulate Light Emission

Biological Strategy

Velvet belly lantern shark

AskNature Team

Modify Light/Color

Color in living systems comes from pigments and the interaction of light with surfaces. Color serves many purposes for living systems, such as attracting prey or mates, providing warnings, or protecting through camouflage. To create the effects needed for each purpose, living systems must control the expression or visibility of pigments and the interactions (such as reflectance and refraction) of light. To do so, they have strategies that modify color or light to increase or decrease the color’s position, intensity, opacity, and more. Male hummingbirds, for example, have brightly colored feather patches on their throats; the coloring comes from pigments, structures that refract light, or a combination of the two. When a male hummingbird hovers near a potential mate, it modifies the angle of these feathers to create a bright, colorful display. However, when it needs to mute the colors to reduce conspicuousness, such as to avoid a predator, it modifies the angle again.

Search this Function

Send Light Signals in the Visible Spectrum

The visible spectrum is the portion of the electromagnetic spectrum that the human eye can detect. Visible light can be thought of in two ways–light as illumination (such as that used by fireflies) and colors that result from light being absorbed or reflected. Living systems use light for a variety of purposes. Sometimes, they use it to make themselves highly visible (like a peacock showing off his brilliant feathers to a potential mate). Other times, they use it to become virtually invisible (like an owl hiding in plain sight when it rests during the day). When a living system sends a light signal, it must create that light or color in an energy- and material-efficient way. Living systems create and enhance color using such strategies as non-toxic pigments, structures that bend and absorb different wavelengths, and chemical processes that create bioluminescence.

Search this Function

Fish

Class Agnatha (“without jaws”), Class Chondrichthyes (“cartilage fish”), Superclass Osteichthyes (“bone fish”): Sharks, eels, snapper, hagfish

The fish are a diverse group, comprising multiple classes within Phylum Animalia. The most well-known classes are Chondrichthyes, which has sharks and rays, and superclass Osteichthyes, which has all bony fish like cod and tuna. Unlike other vertebrates, fish only live in water. They use special adaptations like fins, gills, and swim bladders to survive. Most are ectothermic, meaning their body temperature depends on the water temperature around them. Over half of all vertebrates are fish. They’re found from the bottom of the sea to high mountain lakes.

Search this Living System

A chromatophore iris of the lantern shark reveals bioluminenscence, being triggered by hormones.

“Bioluminescence is a common feature in the permanent darkness of the deep-sea. In fishes, light is emitted by organs containing either photogenic cells (intrinsic photophores), which are under direct nervous control, or symbiotic luminous bacteria (symbiotic photophores), whose light is controlled by secondary means such as mechanical occlusion or physiological suppression. The intrinsic photophores of the lantern shark Etmopterus spinax were recently shown as an exception to this rule since they appear to be under hormonal control. Here, we show that s operate what amounts to a unique light switch, by acting on a chromatophore iris, which regulates light emission by translocation. This result strongly suggests that this shark’s luminescence control originates from the mechanism for physiological colour change found in shallow water sharks that also involves hormonally controlled chromatophores: the lantern shark would have turned the initial shallow water crypsis mechanism into a midwater luminous camouflage, more efficient in the deep-sea environment.” (Claes and Mallefet 2010:685)

“…work on the velvet belly lantern shark (Etmopterus spinax) demonstrated that, unlike any other known system, their luminescence is under hormonal control (Claes & Mallefet 2009a): prolactin and melatonin [hormones] trigger the light emission using specific extrinsic and intrinsic pathways while [alpha]-MSH [hormone] inhibited these light emissions.” (Claes and Mallefet 2010:685)

Last Updated September 14, 2016

References

Journal article

Claes JM; Mallefet J

Other Biological Strategies

Biological Strategy

Fruit Skin Has Bright Blue Pointillist Appearance

Marble berry

The skin of the marble berry has a bright blue pointillist appearance due to distinct reflection of color on layers of cellulose microfibrils.

a hummingbird looks up at a pink flower, its purple neck feathers on full display

Biological Strategy

Harnessing Light: How Microstructures Present Iridescent Colors

Hummingbirds

The iridescent glow of hummingbird feathers arises from the interference of light, facilitated by the intricate and inhomogeneous structure of elliptical platelets embedded within the feather barbules, which manipulate light through their unique microstructural properties

close up a green pine tree with purple tones on the branches in the sunlight

Biological Strategy

Fluorophores Enhance Photosynthesis

The cuticular wax of the dwarf mountain pine enhances photosynthesis by using fluorophores that convert UV light into blue light that can be used for photosynthesis, even under low-light conditions.

Biological Strategy

What Lights a Firefly’s Fire?

Common eastern firefly

The common eastern firefly produces light through a chemical reaction that energizes a molecule so it can release a photon.