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81-513: The stoplight loosejaws are small, deep-sea dragonfishes of the genus Malacosteus , classified either within the subfamily Malacosteinae of the family Stomiidae , or in the separate family Malacosteidae. They are found worldwide, outside of the Arctic and Subantarctic , in the mesopelagic zone below a depth of 500 meters (1,600 feet). This genus once contained three nominal species: M. niger (the type), M. choristodactylus , and M. danae , with

162-448: A stratum germinativum and stratum corneum , but the other intermediate layers found in humans are not always distinguishable. Hair is a distinctive feature of mammalian skin, while feathers are (at least among living species) similarly unique to birds . Birds and reptiles have relatively few skin glands , although there may be a few structures for specific purposes, such as pheromone -secreting cells in some reptiles , or

243-419: A cylindrical shape. When the ducts mature and fill with fluid, the base of the ducts become swollen due to the pressure from the inside. This causes the epidermal layer to form a pit like opening on the surface of the duct in which the inner fluid will be secreted in an upwards fashion. The intercalary region of granular glands is more developed and mature in comparison with mucous glands. This region resides as

324-414: A depth of 500 meters (1,600 feet) in midwater. They are the only known stomiids that do not seem to conduct significant diel vertical migrations . Malacosteus has an elongated body with short, blunt snouts and large eyes that face forward, granting binocular vision . Unlike other stomiids, it has a single round nostril on each side in front of the eye. Relative to its size, Malacosteus has one of

405-463: A different functionality for amphibians than granular. Mucous glands cover the entire surface area of the amphibian body and specialize in keeping the body lubricated. There are many other functions of the mucous glands such as controlling the pH, thermoregulation, adhesive properties to the environment, anti-predator behaviors (slimy to the grasp), chemical communication, even anti-bacterial/viral properties for protection against pathogens. The ducts of

486-450: A long, slender appendage on the chin, called the barbel. The shaft of the barbel is composed of cylindrical muscles, blood vessels and nervous fibers, and the bulb of the barbel has a single photophore. The catecholamine adrenaline is found in the connective tissue within the stem. One hypothesis regarding barbel control is that adrenaline innervation may control both the movement of the barbel and its production of bioluminescence. Data from

567-732: A maximum absorbance at 708 nm (almost infrared ). In live fish, the suborbital and postorbital photophores both flash vigorously, the suborbital at a slower rate. Barbeled dragonfish Aristostomias Astronesthes Bathophilus Bathysphaera ? Borostomias Chauliodus Chirostomias Echiostoma Eupogonesthes Eustomias Flagellostomias Grammatostomias Heterophotus Idiacanthus Leptostomias Malacosteus Melanostomias Neonesthes Odontostomias Opostomias Pachystomias Photonectes Photostomias Rhadinesthes Stomias Tactostoma Thysanactis Trigonolampa Stomiidae

648-460: A modified intercalary region (depending on the function of the glands), yet the majority share the same structure. The alveolar or mucous glands are much more simple and only consist of an epithelium layer as well as connective tissue which forms a cover over the gland. This gland lacks a tunica propria and appears to have delicate and intricate fibers which pass over the gland's muscle and epithelial layers. The epidermis of birds and reptiles

729-417: A numerous individual mucus -secreting skin cells that aid in insulation and protection, but may also have poison glands , photophores , or cells that produce a more watery, serous fluid. In amphibians , the mucous cells are gathered together to form sac-like glands . Most living amphibians also possess granular glands in the skin, that secrete irritating or toxic compounds. Although melanin

810-405: A pigmented sac with a reflective inner lining and an internal mass of gland cells. Inside the gland cells, blue-green light is produced via the same chemical reaction found in other stomiids, which is then absorbed by a protein that fluoresces in a broad red band. This light is then reflected out through the photophore aperture, where it passes through a brown filter, yielding a far-red light with

891-420: A protruding jaw, while the larvae have a rounder shaped mouth and a lower jaw that does not protrude. Additionally, members of this family have a unique head joint that contribute to its ability to open its 'loosejaw' so wide. Deep-sea dragonfish have a flexible connection between the base of the skull and first vertebrae called the occipito-vertebral gap where only the flexible notochord is present. In some taxa

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972-436: A regular pattern. Sonic hedgehog-expressing epidermal cells induce the condensation of cells in the mesoderm . The clusters of mesodermal cells signal back to the epidermis to form the appropriate structure for that position. BMP signals from the epidermis inhibit the formation of placodes in nearby ectoderm. It is believed that the mesoderm defines the pattern. The epidermis instructs the mesodermal cells to condense and then

1053-400: A ring of cells surrounding the basal portion of the duct which are argued to have an ectodermal muscular nature due to their influence over the lumen (space inside the tube) of the duct with dilation and constriction functions during secretions. The cells are found radially around the duct and provide a distinct attachment site for muscle fibers around the gland's body. The gland alveolus is

1134-430: A sac that is divided into three specific regions/layers. The outer layer or tunica fibrosa is composed of densely packed connective-tissue which connects with fibers from the spongy intermediate layer where elastic fibers, as well as nerves, reside. The nerves send signals to the muscles as well as the epithelial layers. Lastly, the epithelium or tunica propria encloses the gland. Mucous glands are non-venomous and offer

1215-543: A secure hold. The connection between the head and the body is reduced, with unossified vertebrae , allowing the cranium to be tilted back and the jaws thrust forward for a wider gape. Finally, the gills are exposed to the outside, allowing the fish to continue respiring while slowly swallowing large prey. However, contrary to its apparent morphological specialization, the diet of Malacosteus consists primarily of zooplankton , chiefly large calanoid copepods , with smaller numbers of krill , shrimps , and fishes . It

1296-486: A study performed on specimens of the Stomias boa species agree with this hypothesis because the barbels of the dragonfish produced light emissions following exposure to external adrenaline. The loose jaw dragonfishes, which include species from Aristostomias , Malacosteus , and Pachystomias , have the ability to detect and produce red bioluminescence. This is made possible by far-red emitting photophores located under

1377-416: A thin sheet of fibers called the basement membrane , which is made through the action of both tissues . The basement membrane controls the traffic of the cells and molecules between the dermis and epidermis but also serves, through the binding of a variety of cytokines and growth factors , as a reservoir for their controlled release during physiological remodeling or repair processes. The dermis

1458-501: A wide range of depths between the surface and thousands of meters deep into the bathypelagic zone , depending on the water's ideal feeding and breeding conditions. There is also some evidence that certain species within the family Stomiidae exhibit migratory behavior . Temperature, salinity, oxygen, and fluorescence profiles of an area can affect some species' (like Sloane's viperfish Chauliodus sloani ) preferred habitat changes from day to night with DVM. Brian Coad, ichthyologist from

1539-544: Is a family of deep-sea ray-finned fish , including the barbeled dragonfishes . They are quite small, usually around 15 cm, up to 26 cm. These fish are apex predators and have enormous jaws filled with fang-like teeth. They are also able to hinge the neurocranium and upper-jaw system, which leads to the opening of the jaw to more than 100 degrees. This ability allows them to consume extremely large prey, often 50% greater than their standard length. The family Stomiidae can be found in all oceans. They also exist at

1620-438: Is closer to that of mammals , with a layer of dead keratin-filled cells at the surface, to help reduce water loss. A similar pattern is also seen in some of the more terrestrial amphibians such as toads . In these animals, there is no clear differentiation of the epidermis into distinct layers, as occurs in humans , with the change in cell type being relatively gradual. The mammalian epidermis always possesses at least

1701-698: Is found between 66° N and 33° S, except for the Mediterranean Sea , while M. australis is found in the southern transition zone between 25° and 45° S, where it is bound by the Antarctic Circumpolar Current . M. niger appears to be replaced by M. australis south of 30° S, while M. australis does not occur north of that latitude outside of the Indian Ocean and the Indo-Australian Archipelago . Both species are usually found below

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1782-407: Is found in the skin of many species, in the reptiles , the amphibians , and fish , the epidermis is often relatively colorless. Instead, the color of the skin is largely due to chromatophores in the dermis , which, in addition to melanin, may contain guanine or carotenoid pigments . Many species, such as chameleons and flounders may be able to change the color of their skin by adjusting

1863-458: Is its unique visual system, which uses a derivative of chlorophyll as a photosensitizer that absorbs long-wave light (around 700 nm) and then indirectly stimulates the fish's two visual pigments, which have maximum absorbances at only 520 and 540 nm. No vertebrates are known to synthesize chlorophyll derivatives, and Malacosteus is believed to obtain these derivatives from the copepods it consumes. The red photophore of Malacosteus consists of

1944-563: Is maintained as a stem cell layer through an autocrine signal, TGF alpha , and through paracrine signaling from FGF7 ( keratinocyte growth factor ) produced by the dermis below the basal cells. In mice, over-expression of these factors leads to an overproduction of granular cells and thick skin. Hair and feathers are formed in a regular pattern and it is believed to be the result of a reaction-diffusion system. This reaction-diffusion system combines an activator, Sonic hedgehog , with an inhibitor, BMP4 or BMP2, to form clusters of cells in

2025-457: Is nearly identical to that of the sea water they inhabit. The transparency is due to a nanoscale structure of hydroxyapatite and collagen, while the tips of the transparent teeth of deep-sea dragonfish were found to emit more red light in seawater which further contributes to its transparency as red light is close to invisible at the depths that the deep-sea dragonfish reside due to a lack of light penetration. The deep-sea dragonfishes are part of

2106-488: Is not directly associated with prey choice, and it is thus hypothesized that it may be used for intraspecific communication. This raises an interesting question of to what extent the red bioluminescence determines dragonfish prey choice. Species of the Stomiidae family use blue bioluminescence for communication, camouflage, and as a luring mechanism. They emit shortwave blue bioluminescence from postorbital photophores and from

2187-562: Is not seen in those with far-red emissions. The foraging strategy they undergo involves remaining in the deep-sea and emitting far-red bioluminescence to illuminate a small area and search for prey. Although Malacosteus, Pachystomias , and Aristostomias all have suborbital photophores that produce red bioluminescence, there are differences in the suborbital photophores between these three genera, in their shape, color, flash duration, and maximum emission. Skin Other animal coverings , such as

2268-468: Is one of the many species of deep-sea fish that can produce their own light through a chemical process known as bioluminescence . A special organ known as a photophore helps produce this light. The deep-sea dragonfishes have large heads, and mouths equipped with many sharp fang-like teeth. They have a long stringlike structure known as a barbel , with a light-producing photophore at the tip, attached to their chin. They also have photophores attached along

2349-509: Is proposed that the specificity of bioluminescent barbel structure to certain species allows for advantageous same-species recognition that promotes genetic isolation, in addition to allowing scientists to more easily identify distinct species due to anatomical barbel differences. The diversity of Stomiidae species is exceptional for their clade age thanks largely to the species-specific barbels. Further, sexual dimorphism of bioluminescence in dragonfish contributes to even greater diversity within

2430-491: Is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis provides tensile strength and elasticity to the skin through an extracellular matrix composed of collagen fibrils , microfibrils , and elastic fibers , embedded in hyaluronan and proteoglycans . Skin proteoglycans are varied and have very specific locations. For example, hyaluronan , versican and decorin are present throughout

2511-421: Is thought that the mechanism of red bioluminescence produced by the suborbital photophore is facilitated by energy transmission and is chemically similar to the blue bioluminescence of the barbel. While suborbital photophores that emit red bioluminescence are particularly helpful for finding prey, since many organisms in the deep sea can only see blue light, it appears as though this red light emission by dragonfish

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2592-471: Is unique amongst animals in using a chlorophyll derivative to perceive red light. The name Malacosteus is derived from the Greek malakos meaning "soft" and osteon meaning "bone". Another common name for these fishes is " rat-trap fish ", from the unusual open structure of their jaws . There are currently two recognized species in this genus: These fishes have a wide distribution in all oceans: M. niger

2673-717: Is yet unclear how Malacosteus captures such small planktonic prey given the open structure of its mouth. The unexpected diet of Malacosteus is theorized to be a result of the small volumes that it searches for food, in which large prey items are rare. The rapid attenuation of red light in sea water gives Malacosteus a shorter visual range than species that use blue light, and it does not migrate vertically into more productive waters like other stomiids. Therefore, its strategy may be one of "snacking" on copepods, which are three orders of magnitude more abundant than fishes at its native depths, in between larger meals. The other factor believed to be partly responsible for Malacosteus' diet

2754-902: The arthropod exoskeleton , have different developmental origin , structure and chemical composition . The adjective cutaneous means "of the skin" (from Latin cutis 'skin'). In mammals , the skin is an organ of the integumentary system made up of multiple layers of ectodermal tissue and guards the underlying muscles , bones , ligaments , and internal organs . Skin of a different nature exists in amphibians , reptiles , and birds . Skin (including cutaneous and subcutaneous tissues) plays crucial roles in formation, structure, and function of extraskeletal apparatus such as horns of bovids (e.g., cattle) and rhinos, cervids' antlers, giraffids' ossicones, armadillos' osteoderm, and os penis / os clitoris . All mammals have some hair on their skin, even marine mammals like whales , dolphins , and porpoises that appear to be hairless. The skin interfaces with

2835-429: The dermis provide nourishment and waste removal from its own cells as well as for the epidermis . Dermis and subcutaneous tissues are thought to contain germinative cells involved in formation of horns, osteoderm, and other extra-skeletal apparatus in mammals. The dermis is tightly connected to the epidermis through a basement membrane and is structurally divided into two areas: a superficial area adjacent to

2916-402: The skull , these scales are lost in tetrapods , although many reptiles do have scales of a different kind, as do pangolins . Cartilaginous fish have numerous tooth-like denticles embedded in their skin, in place of true scales . Sweat glands and sebaceous glands are both unique to mammals , but other types of skin gland are found in other vertebrates . Fish typically have

2997-403: The uropygial gland of most birds. Cutaneous structures arise from the epidermis and include a variety of features such as hair, feathers, claws and nails. During embryogenesis, the epidermis splits into two layers: the periderm (which is lost) and the basal layer . The basal layer is a stem cell layer and through asymmetrical divisions, becomes the source of skin cells throughout life. It

3078-763: The Canada Museum of Nature once observed that there are "64 [species of Dragonfishes] reported from Canada, 5 of which reach the Arctic". These species are most commonly found in the mesopelagic to bathypelagic regions at a depth of 1000m-4000m, and in the Arctic, most samples of these species have been captured along the Davis Strait. The average temperature in these waters is approximately 3–4 °C Some examples of species discovered in that region are: Astronesthes cf. richardsoni; Borostomia antarcticus; Chauliodus sloani; Malacosteus niger; Rhadinesthes decimus; Stomias boa. It

3159-432: The ability to consume more organisms in an extremely food limited environment. On top of an extremely well adapted jaw, members of the Stomiidae family also have teeth that are adapted for hunting in deep sea. Their teeth are sharp, hard, stiff, and transparent when wet, making their teeth dangerous weapons as these teeth become basically invisible in the light absent deep sea. This means the refraction index of their teeth

3240-400: The alveolar gland (sac). Structurally, the duct is derived via keratinocytes and passes through to the surface of the epidermal or outer skin layer thus allowing external secretions of the body. The gland alveolus is a sac-shaped structure that is found on the bottom or base region of the granular gland. The cells in this sac specialize in secretion. Between the alveolar gland and the duct is

3321-401: The amphibians. They are located in clusters differing in concentration depending on amphibian taxa. The toxins can be fatal to most vertebrates or have no effect against others. These glands are alveolar meaning they structurally have little sacs in which venom is produced and held before it is secreted upon defensive behaviors. Structurally, the ducts of the granular gland initially maintain

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3402-468: The body and contain 18–20 and 19–22 rays respectively. The caudal fin is small, with the lower lobe larger than the upper. There are three bioluminescent photophores near the eyes: beneath the eye is a large, teardrop -shaped suborbital photophore that emits red light. Behind it is an ovoid postorbital photophore that emits green light; this photophore is larger in males than females. These red and green photophores are evocative of traffic lights , hence

3483-412: The body mass of themselves. The long "loosejaw" of the dragonfish exhibits increased resistive forces to lower jaw adduction compared to fish with shorter jaws; however, due to decreased surface area of the lower jaw, dragonfish are able to lower the mechanical advantage of adduction and increase adduction velocity through the reduction of resistive forces. Additionally, it is seen that the adductor mass of

3564-429: The body. Microorganisms like Staphylococcus epidermidis colonize the skin surface. The density of skin flora depends on region of the skin. The disinfected skin surface gets recolonized from bacteria residing in the deeper areas of the hair follicle , gut and urogenital openings. The epidermis of fish and of most amphibians consists entirely of live cells , with only minimal quantities of keratin in

3645-414: The cells of the superficial layer. It is generally permeable, and in the case of many amphibians , may actually be a major respiratory organ. The dermis of bony fish typically contains relatively little of the connective tissue found in tetrapods . Instead, in most species, it is largely replaced by solid, protective bony scales . Apart from some particularly large dermal bones that form parts of

3726-570: The deep sea from the surface, many deep-sea organisms are insensitive to red wavelengths, and so to these creatures, red-colored objects appear black. The red photophore of Malacosteus thus allows it to illuminate prey without being detected. These fishes exhibit a number of adaptations for feeding on large prey. The "open" structure of its jaws allows the fish to swing its entire head forward to grab prey from afar in addition to reducing water resistance, allowing them to be snapped shut more quickly, while large recurved teeth and powerful jaw muscles assure

3807-606: The deep sea. Dragonfish use far-red emitting photophores and rhodopsins to detect prey and navigate their habitats. Additionally, dragonfish use chlorophyll in their eyes to detect the weak bioluminescence of their prey, which is an unusual adaptation for a vertebrate. Teleost fishes exhibit a wide range of visual signals, including color, texture, form, and motion, that are used to find mates, establish dominance, defend territory, and coordinate group behavior. Dragonfish have specialized bioluminescent organs that produce red light to communicate with potential mates and prey. Understanding

3888-541: The deep sea. Most deep-sea organisms have only a single visual pigment sensitive to the absorbance ranges of 470–490 nm. This type of optical system is commonly found in the stomiidae family. However, three genera of dragonfish evolved the ability to produce both long-wave and short-wave bioluminescence. In addition, deep-sea dragon fishes evolved retinas with far-red emitting photophores and rhodopsins. These far-red emitting properties produce long-wave bioluminescence greater than 650 nm. This unique evolutionary trait

3969-496: The deep-sea environment. Egg-laying, which predominantly occurs in October, is preceded by a distinctive whirling behavior driven by the male prodding the side of the female's abdomen. Additionally, dragonfish possess a unique adaptation of being able to see using chlorophyll in their eyes, which may allow them to detect the weak bioluminescence of their prey and navigate their dark habitats more effectively. This research sheds light on

4050-416: The dermis and epidermis extracellular matrix , whereas biglycan and perlecan are only found in the epidermis. It harbors many mechanoreceptors (nerve endings) that provide the sense of touch and heat through nociceptors and thermoreceptors . It also contains the hair follicles , sweat glands , sebaceous glands , apocrine glands , lymphatic vessels and blood vessels . The blood vessels in

4131-506: The environment and is the first line of defense from external factors. For example, the skin plays a key role in protecting the body against pathogens and excessive water loss. Its other functions are insulation , temperature regulation , sensation, and the production of vitamin D folates. Severely damaged skin may heal by forming scar tissue . This is sometimes discoloured and depigmented. The thickness of skin also varies from location to location on an organism. In humans, for example,

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4212-408: The epidermis, called the papillary region , and a deep thicker area known as the reticular region . The papillary region is composed of loose areolar connective tissue . This is named for its fingerlike projections called papillae that extend toward the epidermis . The papillae provide the dermis with a "bumpy" surface that interdigitates with the epidermis, strengthening the connection between

4293-589: The eye and rhodopsins that are sensitive to long-wave emissions. This red bioluminescence is used to illuminate prey and to detect other far-red dragonfishes, because it goes undetected by most other species. The species with far-red emitting photophores differ in morphology and behavior from most other dragonfish species. For example, the barbels of these species are more simple in structure than those of other dragonfishes. They also differ in foraging strategies. While most dragonfishes that produce shortwave blue bioluminescence undergo regular diel vertical migrations, this

4374-436: The first to tenth anterior vertebrae are reduced or entirely absent. This gap is the result of notochord elongation in this specific area. Functionally, the gap allows deep-sea dragonfish to pull back their cranium and open their mouths up to 120°, which is significantly farther than other taxa that lack such a head joint. This is what allows deep-sea dragonfish to engulf such large prey, resulting in improved survival through

4455-424: The fish's common name. The third is tiny and round, located between the eye and the large red photophore. Several rows and clusters of blue photophores are present on the sides and belly. In addition, there are small photophores and accessory areas of white luminous tissue scattered over the head and body. The skin is thin and scaleless ; the coloration is black. As long wavelengths of light (i.e. red) do not reach

4536-479: The following functions: Skin is a soft tissue and exhibits key mechanical behaviors of these tissues. The most pronounced feature is the J-curve stress strain response, in which a region of large strain and minimal stress exists and corresponds to the microstructural straightening and reorientation of collagen fibrils. In some cases the intact skin is prestreched, like wetsuits around the diver's body, and in other cases

4617-418: The formation of an extracellular matrix and provide mechanical strength to the skin. Keratinocytes from the stratum corneum are eventually shed from the surface ( desquamation ). The epidermis contains no blood vessels , and cells in the deepest layers are nourished by diffusion from blood capillaries extending to the upper layers of the dermis . The epidermis and dermis are separated by

4698-418: The insulation the skin provides but can also serve as a secondary sexual characteristic or as camouflage . On some animals, the skin is very hard and thick and can be processed to create leather . Reptiles and most fish have hard protective scales on their skin for protection, and birds have hard feathers , all made of tough beta-keratins . Amphibian skin is not a strong barrier, especially regarding

4779-459: The intact skin is under compression. Small circular holes punched on the skin may widen or close into ellipses, or shrink and remain circular, depending on preexisting stresses. Tissue homeostasis generally declines with age, in part because stem /progenitor cells fail to self-renew or differentiate . Skin aging is caused in part by TGF-β by blocking the conversion of dermal fibroblasts into fat cells which provide support. Common changes in

4860-420: The intercalary system which can be summed up as a transitional region connecting the duct to the grand alveolar beneath the epidermal skin layer. In general, granular glands are larger in size than the mucous glands, which are greater in number. Granular glands can be identified as venomous and often differ in the type of toxin as well as the concentrations of secretions across various orders and species within

4941-455: The lower jaw of deep-sea dragonfish is significantly decreased, allowing for increased ability to attain high adduction velocity. This makes the deep-sea dragonfish significantly more competitive when hunting for prey due to its ability to capture large prey quickly and efficiently. An important distinction in jaw morphology between an adult dragonfish and its larvae are the shape of the mouth. The adult fish have an elongated snout-like face with

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5022-689: The major cells , constituting 95% of the epidermis , while Merkel cells , melanocytes and Langerhans cells are also present. The epidermis can be further subdivided into the following strata or layers (beginning with the outermost layer): Keratinocytes in the stratum basale proliferate through mitosis and the daughter cells move up the strata changing shape and composition as they undergo multiple stages of cell differentiation to eventually become anucleated. During that process, keratinocytes will become highly organized, forming cellular junctions ( desmosomes ) between each other and secreting keratin proteins and lipids which contribute to

5103-435: The mesoderm instructs the epidermis of what structure to make through a series of reciprocal inductions. Transplantation experiments involving frog and newt epidermis indicated that the mesodermal signals are conserved between species but the epidermal response is species-specific meaning that the mesoderm instructs the epidermis of its position and the epidermis uses this information to make a specific structure. Skin performs

5184-413: The mucous gland appear as cylindrical vertical tubes that break through the epidermal layer to the surface of the skin. The cells lining the inside of the ducts are oriented with their longitudinal axis forming 90-degree angles surrounding the duct in a helical fashion. Intercalary cells react identically to those of granular glands but on a smaller scale. Among the amphibians, there are taxa which contain

5265-491: The oldest known skin, fossilized about 289 million years ago, and possibly the skin from an ancient reptile. The word skin originally only referred to dressed and tanned animal hide and the usual word for human skin was hide. Skin is a borrowing from Old Norse skinn "animal hide, fur", ultimately from the Proto-Indo-European root *sek-, meaning "to cut" (probably a reference to the fact that in those times animal hide

5346-411: The passage of chemicals via skin, and is often subject to osmosis and diffusive forces. For example, a frog sitting in an anesthetic solution would be sedated quickly as the chemical diffuses through its skin. Amphibian skin plays key roles in everyday survival and their ability to exploit a wide range of habitats and ecological conditions. On 11 January 2024, biologists reported the discovery of

5427-420: The relative size of their chromatophores . Amphibians possess two types of glands , mucous and granular (serous). Both of these glands are part of the integument and thus considered cutaneous . Mucous and granular glands are both divided into three different sections which all connect to structure the gland as a whole. The three individual parts of the gland are the duct, the intercalary region, and lastly

5508-505: The reproductive behavior and early life stages of the naked dragonfish and contributes to our understanding of the ecology and behavior of dragonfish species. One study focuses on the stomiid family, which includes loosejaws and dragonfishes, analyzing the genetic makeup of the visual pigments in these fish and how they have adapted to the unique light conditions of the deep-sea environment. The research helps us understand how dragonfish behavior and vision have evolved to allow them to thrive in

5589-402: The reproductive system. The female adult stomiids are also larger than the males. Dragonfish are a type of teleost fish that inhabit the deep sea and use bioluminescence to detect prey and communicate with potential mates. They possess far-red emitting photophores and rhodopsins that are sensitive to long-wave emissions greater than 650 nm, and have adapted to the unique light conditions of

5670-581: The reticular region are the roots of the hair , sweat glands , sebaceous glands , receptors , nails , and blood vessels . The subcutaneous tissue (also hypodermis) is not part of the skin, and lies below the dermis . Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves . It consists of loose connective tissue and elastin . The main cell types are fibroblasts , macrophages and adipocytes (the subcutaneous tissue contains 50% of body fat ). Fat serves as padding and insulation for

5751-495: The sides of their body. A specific species of Stomiidae, the Chauliodus, cannot luminesce longer than 30 minutes without adrenaline. However, in presence of adrenaline, it can produce light for many hours. They produce blue-green light, the wavelengths of which can travel the farthest in the ocean. The deep-sea dragonfish waves its barbel back and forth and produces flashing lights on and off to attract prey and potential mates. Many of

5832-422: The skin located under the eyes and around the eyelids is the thinnest skin on the body at 0.5 mm thick and is one of the first areas to show signs of aging such as "crows feet" and wrinkles. The skin on the palms and the soles of the feet is the thickest skin on the body at 4 mm thick. The speed and quality of wound healing in skin is promoted by estrogen . Fur is dense hair. Primarily, fur augments

5913-429: The species they prey upon also produce light themselves, which is why they have evolved to have black stomach walls to keep the lights concealed while digesting their meal in order to stay hidden from their predators. The jaw of members in the Stomiidae family is adapted extremely well for survival and predation in the deep sea. Although small in size, the dragonfish jaw is adapted to capture large prey that are up to 50%

5994-459: The species, but the greater abundance of immature specimens within research collections makes studying sexual dimorphism challenging. In addition to a bioluminescent barbel, members of the Stomiidae family have a blue light emitting photophore in the postorbital region. Some dragonfish, such as the Malacosteus niger, also have a unique red light emitting photophore in the suborbital region. It

6075-415: The stomiidae family, making up a clade of 28 genera and 290 species. The dragonfish possess unique adaptations to help them thrive in the deepest parts of the ocean. This family species have been discovered to use certain long-wave and short-wave bioluminescence to communicate, lure prey, distract predators, and camouflage themselves. The stomiidae family has many unique adaptations to their sensory organs for

6156-418: The two layers of skin. The reticular region lies deep in the papillary region and is usually much thicker. It is composed of dense irregular connective tissue and receives its name from the dense concentration of collagenous , elastic , and reticular fibers that weave throughout it. These protein fibers give the dermis its properties of strength , extensibility , and elasticity . Also located within

6237-590: The validity of the latter two species being challenged by different authors at various times. In 2007, Kenaley examined over 450 stoplight loosejaw specimens and revised the genus to contain two species, M. niger and the new M. australis . Malacosteus and the related genera Aristostomias , Chirostomias and Pachystomias are the only fishes that produce red bioluminescence . As most of their prey organisms are not capable of perceiving light at those wavelengths, this allows Malacosteus to hunt with an essentially invisible beam of light. Furthermore, Malacosteus

6318-445: The visual communication and behavior of teleost fishes is essential to understanding the behavior of dragonfish in their natural habitats. Dragonfish of the Stomiidae family are largely characterized by their bioluminescent barbels, which act as lures for prey and are a species-specific structure. These barbels extend anteriorly off the bottom jaw, and prey attracted to its bioluminescence include lanternfish and bristlemouths . It

6399-555: The widest gapes of any fish, with a lower jaw measuring one-quarter of the fish's length. The lower jaw has no ethmoid membrane (floor) and is attached only by the hinge and a modified tongue bone. There are several large, fang-like teeth in the front of the jaws, followed by many small barbed teeth. There are several groups of pharyngeal teeth that serve to direct food down the esophagus . The pectoral and pelvic fins are moderately long, containing 3–4 and 6 fin rays respectively. The dorsal and anal fins are placed far back on

6480-453: Was commonly cut off to be used as garment). Mammalian skin is composed of two primary layers: The epidermis is composed of the outermost layers of the skin. It forms a protective barrier over the body's surface, responsible for keeping water in the body and preventing pathogens from entering, and is a stratified squamous epithelium , composed of proliferating basal and differentiated suprabasal keratinocytes . Keratinocytes are

6561-543: Was first seen around 15.4 Ma and had a single evolutionary origin within the stomiidae family. Dragonfish females exhibit two distinct cohorts oocytes, one which is a white cream color during the first growing stage and the other which is orange-reddish in vitellogenesis. The orange-reddish ovaries are released in the current spawning season, while the other batch is in the growing stage. Stomiids are gonochoristic, allowing them to increase their reproductive fitness by using their energy to produce gametes instead of reconfiguring

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