101-569: Photorhabdus is a genus of bioluminescent , gram-negative bacilli which lives symbiotically within entomopathogenic nematodes , hence the name photo (which means light producing) and rhabdus (rod shape). Photorhabdus is known to be pathogenic to a wide range of insects and has been used as biopesticide in agriculture. Photorhabdus species facilitate the reproduction of entomopathogenic nematodes by infecting and killing susceptible insect larvae. Entomopathogenic nematodes are normally found in soil. Nematodes infect larval hosts by piercing
202-549: A backbone or spine, consisting of vertebrae and intervertebral discs . The vertebrae are irregular bones , and the intervertebral discs are of fibrocartilage . The vertebral column surrounds and protects the spinal cord . The other feature unique to vertebrates is the presence of a cranium , or skull. The vertebrates make up the subphylum Vertebrata with some 65,000 species in the phylum Chordata . The vertebrates include mammals , birds , amphibians , and various classes of reptiles and fish . Classes of fish include
303-491: A vestigial coccyx . A dorsal nerve cord , which folds and fuses into a hollow neural tube during embryonic development and eventually gives rise to the brain and spinal cord , runs more dorsally to the axial endoskeleton, enclosed by neural arches , with a fore-end enlargement within a skeletonized braincase . This provides an alternative name for vertebrates, the craniates . All vertebrate embryos develop transient pharyngeal arches ; in fish, these develop into
404-451: A black lining able to keep the light from any bioluminescent fish prey which they have swallowed from attracting larger predators. The sea-firefly is a small crustacean living in sediment. At rest it emits a dull glow but when disturbed it darts away leaving a cloud of shimmering blue light to confuse the predator. During World War II it was gathered and dried for use by the Japanese army as
505-640: A bright enough wake to be detected; a German submarine was sunk in the First World War , having been detected in this way. The Navy was interested in predicting when such detection would be possible, and hence guiding their own submarines to avoid detection. Among the anecdotes of navigation by bioluminescence is one recounted by the Apollo 13 astronaut Jim Lovell , who as a Navy pilot had found his way back to his aircraft carrier USS Shangri-La when his navigation systems failed. Turning off his cabin lights, he saw
606-417: A central nervous system arising from a single nerve cord dorsal to the gut tube , headed by a series of (typically paired) brain vesicles, is unique to vertebrates. This is in stark contrast to invertebrates with well-developed central nervous systems such as arthropods and cephalopods , which have an often ladder-like ventral nerve cord made of paired segmental ganglia on the opposite ( ventral ) side of
707-401: A common ancestor. However, he found this hypothesis to be false, with different organisms having major differences in the composition of their light-producing proteins. He spent the next 30 years purifying and studying the components, but it fell to the young Japanese chemist Osamu Shimomura to be the first to obtain crystalline luciferin. He used the sea firefly Vargula hilgendorfii , but it
808-525: A hollow neural tube ) running along the dorsal aspect of the notochord . Of particular importance and unique to vertebrates is the presence of neural crest cells, which are progenitor cells critical to coordinating the functions of cellular components. Neural crest cells migrate through the body from the dorsal nerve cord during development, initiate the formation of neuronal ganglia and various special sense organs. The peripheral nervous system forms when neural crest cells branch out laterally from
909-433: A long-lasting glow which the fish can control. The glowing esca is dangled or waved about to lure small animals to within striking distance of the fish. The cookiecutter shark uses bioluminescence to camouflage its underside by counter-illumination, but a small patch near its pectoral fins remains dark, appearing as a small fish to large predatory fish like tuna and mackerel swimming beneath it. When such fish approach
1010-498: A longer, red wavelength. The dragonfish species which produce the red light also produce blue light in photophore on the dorsal area. The main function of this is to alert the fish to the presence of its prey. The additional pigment is thought to be assimilated from chlorophyll derivatives found in the copepods which form part of its diet. Vertebrate Ossea Batsch, 1788 Vertebrates ( / ˈ v ɜːr t ə b r ɪ t s , - ˌ b r eɪ t s / ) are animals with
1111-405: A majority are found in symbiotic relationships that involve fish, squids, crustaceans etc. as hosts. Most luminous bacteria inhabit the sea, dominated by Photobacterium and Vibrio . In the symbiotic relationship, bacterium benefit from having a source of nourishment and a refuge to grow. Hosts obtain these bacterial symbionts either from the environment, spawning , or the luminous bacterium
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#17328547473171212-454: A molecule called 3,5-Dihydroxy-4-isopropyl-trans-stilbene (ST). It is proposed that ST acts as an antibiotic and protects Photorhabdus species from competition from other microorganisms, and also helps circumvent the insect's immune system. Photorhabdus species are essential endosymbionts for Heterorhabditis nematodes. The complete genome of Photorhabdus luminescens was sequenced in 2003. The DNA sequence of Photorhabdus contains
1313-502: A number of toxin-encoding genes that are essential for killing the insect after infection. This includes genes encoding toxins that kill Manduca sexta , the tobacco hornworm, gene mcf that causes apoptosis in insect hemocytes and midgut epithelium, and genes that intervene in the development of insect host. Another important sequence identified is the gene encoding polyketide and nonribosomal peptide syntheses which produce antibiotics to protect against microbial competitors. It
1414-589: A protein related to ubiquitin carboxyl-terminal hydrolase are exclusively shared by all vertebrates and reliably distinguish them from all other animals. A specific relationship between vertebrates and tunicates is strongly supported by two CSIs found in the proteins Rrp44 (associated with the exosome complex ) and serine palmitoyltransferase . These are exclusively shared by species from these two subphyla, but not cephalochordates . This indicates hat vertebrates are more closely related to tunicates than cephalochordates. The "Notochordata hypothesis" suggested that
1515-485: A role in the regulation of luminescence in many species of bacteria. Small extracellularly secreted molecules stimulate the bacteria to turn on genes for light production when cell density, measured by concentration of the secreted molecules, is high. Pyrosomes are colonial tunicates and each zooid has a pair of luminescent organs on either side of the inlet siphon. When stimulated by light, these turn on and off, causing rhythmic flashing. No neural pathway runs between
1616-426: A source of light during clandestine operations. The larvae of railroad worms ( Phrixothrix ) have paired photic organs on each body segment, able to glow with green light; these are thought to have a defensive purpose. They also have organs on the head which produce red light; they are the only terrestrial organisms to emit light of this color. Aposematism is a widely used function of bioluminescence, providing
1717-542: A warning that the creature concerned is unpalatable. It is suggested that many firefly larvae glow to repel predators; some millipedes glow for the same purpose. Some marine organisms are believed to emit light for a similar reason. These include scale worms , jellyfish and brittle stars but further research is needed to fully establish the function of the luminescence. Such a mechanism would be of particular advantage to soft-bodied cnidarians if they were able to deter predation in this way. The limpet Latia neritoides
1818-462: A weak source of light. This experimental form of illumination avoided the necessity of using candles which risked sparking explosions of firedamp . In 1920, the American zoologist E. Newton Harvey published a monograph, The Nature of Animal Light , summarizing early work on bioluminescence. Harvey notes that Aristotle mentions light produced by dead fish and flesh, and that both Aristotle and Pliny
1919-416: Is evolving with their host. Coevolutionary interactions are suggested as host organisms' anatomical adaptations have become specific to only certain luminous bacteria, to suffice ecological dependence of bioluminescence. Bioluminescence is widely studied amongst species located in the mesopelagic zone, but the benthic zone at mesopelagic depths has remained widely unknown. Benthic habitats at depths beyond
2020-419: Is expelled, distracting or repelling a potential predator, while the animal escapes to safety. The deep sea squid Octopoteuthis deletron may autotomize portions of its arms which are luminous and continue to twitch and flash, thus distracting a predator while the animal flees. Dinoflagellates may use bioluminescence for defense against predators . They shine when they detect a predator, possibly making
2121-440: Is found in invertebrate chordates such as lancelets (a sister subphylum known as the cephalochordates ), though it lacks eyes and other complex special sense organs comparable to those of vertebrates. Other chordates do not show any trends towards cephalization. The rostral end of the neural tube is expanded by a thickening of the walls and expansion of the central canal of spinal cord into three primary brain vesicles :
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#17328547473172222-546: Is in the blue and green light spectrum . However, some loose-jawed fish emit red and infrared light, and the genus Tomopteris emits yellow light. The most frequently encountered bioluminescent organisms may be the dinoflagellates in the surface layers of the sea, which are responsible for the sparkling luminescence sometimes seen at night in disturbed water. At least 18 genera of these phytoplankton exhibit luminosity. Luminescent dinoflagellate ecosystems are present in warm water lagoons and bays with narrow openings to
2323-425: Is no conclusive evidence that the cockroaches are bioluminescent. While most marine bioluminescence is green to blue, some deep sea barbeled dragonfishes in the genera Aristostomias , Pachystomias and Malacosteus emit a red glow. This adaptation allows the fish to see red-pigmented prey, which are normally invisible to other organisms in the deep ocean environment where red light has been filtered out by
2424-406: Is prevalent in the pelagic zone such as counter-illumination may not be functional or relevant in the benthic realm. Bioluminescence in bathyal benthic species still remains poorly studied due to difficulties of the collection of species at these depths. Bioluminescence has several functions in different taxa. Steven Haddock et al. (2010) list as more or less definite functions in marine organisms
2525-434: Is proposed that Photorhabdus species acquired the toxin genes by horizontal gene transfer during evolution. The efficiency of insect-killing nature of Photorhabdus species and its potential use as biopesticide have been studied. Use of Photorhabdus species alone as biopesticide, independent of its nematode symbiont, against the cabbage white butterfly, Pieris brassicae , mango mealy bug, Drosicha mangiferae and
2626-582: Is regenerated from the oxidized (oxyluciferin) form, allowing it to recombine with aequorin, in preparation for a subsequent flash. Photoproteins are thus enzymes , but with unusual reaction kinetics. Furthermore, some of the blue light released by aequorin in contact with calcium ions is absorbed by a green fluorescent protein , which in turn releases green light in a process called resonant energy transfer . Overall, bioluminescence has arisen over 40 times in evolutionary history. In evolution , luciferins tend to vary little: one in particular, coelenterazine ,
2727-512: Is that bioluminescence has evolved independently at least 40 times. Bioluminescence in fish began at least by the Cretaceous period. About 1,500 fish species are known to be bioluminescent; the capability evolved independently at least 27 times. Of these, 17 involved the taking up of bioluminous bacteria from the surrounding water while in the others, the intrinsic light evolved through chemical synthesis. These fish have become surprisingly diverse in
2828-544: Is the light emitting pigment for nine phyla (groups of very different organisms), including polycystine radiolaria , Cercozoa ( Phaeodaria ), protozoa , comb jellies , cnidaria including jellyfish and corals , crustaceans , molluscs , arrow worms and vertebrates ( ray-finned fish ). Not all these organisms synthesise coelenterazine: some of them obtain it through their diet. Conversely, luciferase enzymes vary widely and tend to be different in each species. Bioluminescence occurs widely among animals, especially in
2929-534: Is the only known bioluminescent terrestrial mollusk. Pulses of light are emitted from a gland near the front of the foot and may have a communicative function, although the adaptive significance is not fully understood. Bioluminescence is used by a variety of animals to mimic other species. Many species of deep sea fish such as the anglerfish and dragonfish make use of aggressive mimicry to attract prey . They have an appendage on their heads called an esca that contains bioluminescent bacteria able to produce
3030-401: Is the only known freshwater gastropod that emits light. It produces greenish luminescent mucus which may have an anti-predator function. The marine snail Hinea brasiliana uses flashes of light, probably to deter predators. The blue-green light is emitted through the translucent shell, which functions as an efficient diffuser of light. Communication in the form of quorum sensing plays
3131-406: Is the production and emission of light by living organisms . It is a form of chemiluminescence . Bioluminescence occurs widely in marine vertebrates and invertebrates , as well as in some fungi , microorganisms including some bioluminescent bacteria , and terrestrial arthropods such as fireflies . In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from
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3232-420: Is used for camouflage by counterillumination , in which the animal matches the overhead environmental light as seen from below. In these animals, photoreceptors control the illumination to match the brightness of the background. These light organs are usually separate from the tissue containing the bioluminescent bacteria. However, in one species, Euprymna scolopes , the bacteria are an integral component of
3333-617: The Cephalochordata is the sister taxon to Craniata (Vertebrata). This group, called the Notochordata, was placed as sister group to the Tunicata (Urochordata). Studies since 2006 analyzing large sequencing datasets however strongly support Olfactores (tunicates + vertebrates) as a clade, and hence the placement of Cephalochordata as sister-group to Olfactores (known as the " Olfactores hypothesis "). The following cladogram summarizes
3434-548: The Chengjiang biota and lived about 518 million years ago. These include Haikouichthys , Myllokunmingia , Zhongjianichthys , and probably Haikouella . Unlike the other fauna that dominated the Cambrian, these groups had the basic vertebrate body plan: a notochord, rudimentary vertebrae, and a well-defined head and tail. All of these early vertebrates lacked jaws in the common sense and relied on filter feeding close to
3535-474: The Izu–Ogasawara Trench at a depth of 8,336 metres (27,349 feet). Many fish varieties are the main predators in most of the world's freshwater and marine water bodies . The rest of the vertebrate species are tetrapods, a single lineage that includes amphibians (with roughly 7,000 species); mammals (with approximately 5,500 species); and reptiles and birds (with about 20,000 species divided evenly between
3636-623: The Jurassic . The Cenozoic world saw great diversification of bony fishes, amphibians, reptiles, birds and mammals. Over half of all living vertebrate species (about 32,000 species) are fish (non-tetrapod craniates), a diverse set of lineages that inhabit all the world's aquatic ecosystems, from the Tibetan stone loach ( Triplophysa stolickai ) in western Tibetan hot springs near Longmu Lake at an elevation of 5,200 metres (17,100 feet) to an unknown species of snailfish (genus Pseudoliparis ) in
3737-458: The Latin vertebratus ("jointed"), from vertebra meaning "joint", in turn from Latin vertere to turn. All vertebrates are built along the basic chordate body plan of five shared characteristics . These are a rigid axial skeleton that includes a vertebral column developed around an elastic or flexible notochord , and a skull. The notochord stretches out for almost the whole length of
3838-562: The Placodermi and the Acanthodii , both considered paraphyletic . Other ways of classifying the vertebrates have been devised, particularly with emphasis on the phylogeny of early amphibians and reptiles. An example based on Janvier (1981, 1997), Shu et al. (2003), and Benton (2004) is given here († = extinct ): While this traditional classification is orderly, most of the groups are paraphyletic , i.e. do not contain all descendants of
3939-400: The blue whale , at up to 33 m (108 ft). With only one exception, the defining characteristics of a vertebrate are the vertebral column , and the skull . The embryonic notochord is replaced by a segmented series of irregular bones known as vertebrae . The vertebrae are separated by intervertebral discs of fibrocartilage , which are remnants of the notochord. Hagfish are
4040-462: The branchial arches that support the gills . An organ in the pharynx , the endostyle , which assists in filter feeding in adult cephalochordates and urochordates , and in the larvae of lampreys , has evolved into the thyroid in most vertebrates. Vertebrates vary in body length ranging from the frog species Brachycephalus pulex , a Brazilian flea toad, with a minimum adult snout–vent length of 6.45 millimetres (0.254 in) to
4141-404: The firefly luciferase . Generically, this reaction can be described as: Instead of a luciferase, the jellyfish Aequorea victoria makes use of another type of protein called a photoprotein , in this case specifically aequorin . When calcium ions are added, rapid catalysis creates a brief flash quite unlike the prolonged glow produced by luciferase. In a second, much slower step, luciferin
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4242-565: The genetics of organisms. Phylogenetic classification is based solely on phylogeny . Evolutionary systematics gives an overview; phylogenetic systematics gives detail. The two systems are thus complementary rather than opposed. Conventional classification has extant vertebrates grouped into seven classes based on traditional interpretations of gross anatomical and physiological traits. The commonly held classification lists three classes of fish and four of tetrapods . In addition to these, there are two classes of extinct armoured fishes,
4343-410: The prosencephalon ( forebrain ), mesencephalon ( midbrain ) and rhombencephalon ( hindbrain ), which are further differentiated in the various vertebrate groups. Two laterally placed retinas and optical nerves form around outgrowths from the midbrain, except in hagfish which may have secondarily lost the structures. The forebrain is more well-developed in most tetrapods and subdivided into
4444-432: The telencephalon and diencephalon , while the midbrain dominates in fish and some salamanders . In vertebrates with paired appendages, especially tetrapods, a pair of secondary enlargements of the hindbrain become the cerebella , which modulate complex motor coordinations . The brain vesicles are usually bilaterally symmetrical , giving rise to the paired cerebral hemispheres in mammals . The resultant anatomy of
4545-489: The Elder (in his Natural History ) mention light from damp wood. He records that Robert Boyle experimented on these light sources, and showed that both they and the glowworm require air for light to be produced. Harvey notes that in 1753, J. Baker identified the flagellate Noctiluca "as a luminous animal" "just visible to the naked eye", and in 1854 Johann Florian Heller (1813–1871) identified strands ( hyphae ) of fungi as
4646-632: The Elder mentioned that damp wood sometimes gives off a glow. Many centuries later Robert Boyle showed that oxygen was involved in the process, in both wood and glowworms. It was not until the late nineteenth century that bioluminescence was properly investigated. The phenomenon is widely distributed among animal groups, especially in marine environments. On land it occurs in fungi, bacteria and some groups of invertebrates , including insects . The uses of bioluminescence by animals include counterillumination camouflage, mimicry of other animals, for example to lure prey, and signaling to other individuals of
4747-500: The Oplophoridae family, uses its photophores to emit light, and can secrete a bioluminescent substance when in the presence of a predator. This secretory mechanism is common among prey fish. Many cephalopods , including at least 70 genera of squid , are bioluminescent. Some squid and small crustaceans use bioluminescent chemical mixtures or bacterial slurries in the same way as many squid use ink . A cloud of luminescent material
4848-468: The abdomen when flying and a green light from the thorax when they are disturbed or moving about on the ground. The former is probably a sexual attractant but the latter may be defensive. Larvae of the click beetle Pyrophorus nyctophanus live in the surface layers of termite mounds in Brazil. They light up the mounds by emitting a bright greenish glow which attracts the flying insects on which they feed. In
4949-480: The animal's light organ. Bioluminescence is used in a variety of ways and for different purposes. The cirrate octopod Stauroteuthis syrtensis uses emits bioluminescence from its sucker like structures. These structures are believed to have evolved from what are more commonly known as octopus suckers. They do not have the same function as the normal suckers because they no longer have any handling or grappling ability due its evolution of photophores . The placement of
5050-521: The atmosphere" was probably responsible. Daniel Pauly comments that Darwin "was lucky with most of his guesses, but not here", noting that biochemistry was too little known, and that the complex evolution of the marine animals involved "would have been too much for comfort". Bioluminescence attracted the attention of the United States Navy in the Cold War , since submarines in some waters can create
5151-473: The body of a chordate , it lies dorsal to the gastrointestinal tract and provides flexible support to the body. The notochord remains in the jawless fish and cephalochordates (non-vertebrate chordates). In vertebrates it becomes replaced either wholly or in part by the vertebral column. The vertebral column typically continues beyond the rear orifice ( anus , or cloaca ) to form an elongated tail . Some vertebrates evolved to become tailless with only
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#17328547473175252-427: The brain (which itself is a fused cluster of segmental ganglia from the rostral metameres ). Molecular markers known as conserved signature indels (CSIs) in protein sequences have been identified and provide distinguishing criteria for the vertebrate subphylum. Specifically, 5 CSIs in the following proteins: protein synthesis elongation factor-2 , eukaryotic translation initiation factor 3 , adenosine kinase and
5353-700: The cases are mostly non-fatal and are restricted to the US state of Texas and the Gold Coast of Australia. The first case of human infection was reported by the Centers for Disease Control in the United States in 1989. In 1999, a study reported another four cases of Photorhabdus luminescens infection in south eastern Australia, one in 1994 and three in 1998. "Photorhabdus" . National Center for Biotechnology Information (NCBI) . Bioluminescent Bioluminescence
5454-444: The chemical mechanisms or to prove what function the light serves. In some cases the function is unknown, as with species in three families of earthworm ( Oligochaeta ), such as Diplocardia longa , where the coelomic fluid produces light when the animal moves. The following functions are reasonably well established in the named organisms. In many animals of the deep sea, including several squid species, bacterial bioluminescence
5555-409: The class's common ancestor. For instance, descendants of the first reptiles include modern reptiles, mammals and birds; the agnathans have given rise to the jawed vertebrates ; the bony fishes have given rise to the land vertebrates ; the traditional " amphibians " have given rise to the reptiles (traditionally including the synapsids or mammal-like "reptiles"), which in turn have given rise to
5656-472: The dead insect thus assisting in the dispersal of both bacteria and nematodes. A similar reason may account for the many species of fungi that emit light. Species in the genera Armillaria , Mycena , Omphalotus , Panellus , Pleurotus and others do this, emitting usually greenish light from the mycelium , cap and gills . This may attract night-flying insects and aid in spore dispersal, but other functions may also be involved. Quantula striata
5757-757: The deep ocean and control their light with the help of their nervous system, using it not just to lure prey or hide from predators, but also for communication. All bioluminescent organisms have in common that the reaction of a "luciferin" and oxygen is catalyzed by a luciferase to produce light. McElroy and Seliger proposed in 1962 that the bioluminescent reaction evolved to detoxify oxygen, in parallel with photosynthesis. Thuesen, Davis et al. showed in 2016 that bioluminescence has evolved independently 27 times within 14 fish clades across ray-finned fishes. The oldest of these appears to be Stomiiformes and Myctophidae. In sharks, bioluminescence has evolved only once. Genomic analysis of octocorals indicates that their ancestor
5858-551: The demise of virtually all jawless fishes save for lampreys and hagfishes, as well as the Placodermi , a group of armoured fish that dominated the entirety of that period since the late Silurian as well as the eurypterids , dominant animals of the preceding Silurian , and the anomalocarids . By the middle of the Devonian, several droughts, anoxic events and oceanic competition led a lineage of sarcopterygii to leave water, eventually establishing themselves as terrestrial tetrapods in
5959-695: The development of increased eye sensitivity and enhanced visual signals. If selection were to favor a mutation in the oxygenase enzyme required for the breakdown of pigment molecules (molecules often associated with spots used to attract a mate or distract a predator) it could have eventually resulted in external luminescence in tissues. Rees et al. use evidence gathered from the marine luciferin coelenterazine to suggest that selection acting on luciferins may have arisen from pressures to protect oceanic organisms from potentially deleterious reactive oxygen species (e.g. H 2 O 2 and O 2 ). The functional shift from antioxidation to bioluminescence probably occurred when
6060-408: The dorsal nerve cord and migrate together with the mesodermal somites to innervate the various different structures that develop in the body. The vertebrates are the only chordate group with neural cephalization , and their neural functions are centralized towards a series of enlarged clusters in the head , which give rise to a brain . A slight swelling of the anterior end of the nerve cord
6161-583: The enzyme catalyzes the oxidation of the luciferin. In some species, the luciferase requires other cofactors , such as calcium or magnesium ions, and sometimes also the energy-carrying molecule adenosine triphosphate (ATP). In evolution , luciferins vary little: one in particular, coelenterazine , is found in 11 different animal phyla , though in some of these, the animals obtain it through their diet. Conversely, luciferases vary widely between different species. Bioluminescence has arisen over 40 times in evolutionary history . Both Aristotle and Pliny
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#17328547473176262-417: The female lights up to attract males. The defense mechanisms for bioluminescent organisms can come in multiple forms; startling prey, counter-illumination, smoke screen or misdirection, distractive body parts, burglar alarm, sacrificial tag or warning coloration. The shrimp family Oplophoridae Dana use their bioluminescence as a way of startling the predator that is after them. Acanthephyra purpurea , within
6363-483: The first gill arch pair evolved into the jointed jaws and form an additional oral cavity ahead of the pharynx . Research also suggests that the sixth branchial arch contributed to the formation of the vertebrate shoulder, which separated the head as a distinct part of the body. In amphibians and some primitive bony fishes, the larvae bear external gills , branching off from the gill arches. These are reduced in adulthood, their respiratory function taken over by
6464-434: The following: defensive functions of startle, counterillumination (camouflage), misdirection (smoke screen), distractive body parts, burglar alarm (making predators easier for higher predators to see), and warning to deter settlers; offensive functions of lure, stun or confuse prey, illuminate prey, and mate attraction/recognition. It is much easier for researchers to detect that a species is able to produce light than to analyze
6565-435: The genus Vibrio ; in others, it is autogenic, produced by the animals themselves. In a general sense, the principal chemical reaction in bioluminescence involves a light-emitting molecule and an enzyme , generally called luciferin and luciferase , respectively. Because these are generic names, luciferins and luciferases are often distinguished by the species or group, e.g. firefly luciferin . In all characterized cases,
6666-421: The gill arches form during fetal development , and form the basis of essential structures such as jaws , the thyroid gland , the larynx , the columella (corresponding to the stapes in mammals ) and, in mammals, the malleus and incus . The central nervous system of vertebrates is based on the embryonic dorsal nerve cord (which then flattens into a neural plate before folding and fusing over into
6767-402: The glowing wake of the ship, and was able to fly to it and land safely. The French pharmacologist Raphaël Dubois carried out work on bioluminescence in the late nineteenth century. He studied click beetles ( Pyrophorus ) and the marine bivalve mollusc Pholas dactylus . He refuted the old idea that bioluminescence came from phosphorus, and demonstrated that the process was related to
6868-400: The gut tube, with a split brain stem circumventing the foregut around each side to form a brain on the dorsal side of the mouth . The higher functions of the vertebrate CNS are highly centralized towards the brain (particularly the forebrain), while the invertebrate CNS is significantly more decentralized with the segmental ganglia having substantial neural autonomy independent of
6969-651: The head, bordering the posterior margins of a series of crescentic openings from the pharynx to the outside. Each gill is supported by a cartilaginous or bony gill arch , which develop embryonically from pharyngeal arches . Bony fish have three pairs of gill arches, cartilaginous fish have five to seven pairs, while the primitive jawless fish have seven pairs. The ancestral vertebrates likely had more arches than seven, as some of their chordate relatives have more than 50 pairs of gill opens, although most, if not all, of these openings are actually involved in filter feeding rather than respiration . In jawed vertebrates ,
7070-443: The internal gills proper in fishes and by cutaneous respiration in most amphibians. While some amphibians such as axolotl retain the external gills into adulthood, the complex internal gill system as seen in fish apparently being irrevocably lost very early in the evolution of tetrapods , who evolved lungs (which are homologous to swim bladders ) to breathe air. While the more specialized terrestrial vertebrates lack gills,
7171-407: The jawless Agnatha , and the jawed Gnathostomata . The jawed fish include both the cartilaginous fish and the bony fish . Bony fish include the lobe-finned fish , which gave rise to the tetrapods , the animals with four limbs. Vertebrates make up less than five percent of all described animal species ; the rest are all invertebrates , that lack a backbone. The word 'vertebrate' derives from
7272-502: The larval cuticle. When the nematode enters an insect larvae, Photorhabdus species are released by the nematodes and will produce a range of toxins, killing the host within 48 hours. Photorhabdus species feed on the cadaver of the insect and the process converts the cadaver into a nutrient source for the nematode. Mature nematodes leave the depleted body of the insect and search for new hosts to infect. During stationary phase growth inside insect larvae, Photorhabdus species synthesize
7373-553: The lure, they are bitten by the shark. Female Photuris fireflies sometimes mimic the light pattern of another firefly, Photinus , to attract its males as prey. In this way they obtain both food and the defensive chemicals named lucibufagins , which Photuris cannot synthesize. South American giant cockroaches of the genus Lucihormetica were believed to be the first known example of defensive mimicry, emitting light in imitation of bioluminescent, poisonous click beetles. However, doubt has been cast on this assertion, and there
7474-460: The mammals and birds. Most scientists working with vertebrates use a classification based purely on phylogeny , organized by their known evolutionary history and sometimes disregarding the conventional interpretations of their anatomy and physiology. In phylogenetics , the relationships between animals are illustrated as a hierarchy known as a phylogenetic tree . The cladogram below is based on studies compiled by Philippe Janvier and others for
7575-458: The marine environment, use of luminescence for mate attraction is chiefly known among ostracods , small shrimp-like crustaceans , especially in the family Cyprididae . Pheromones may be used for long-distance communication, with bioluminescence used at close range to enable mates to "home in". A polychaete worm, the Bermuda fireworm creates a brief display, a few nights after the full moon, when
7676-403: The mesopelagic are also poorly understood due to the same constraints. Unlike the pelagic zone where the emission of light is undisturbed in the open sea, the occurrence of bioluminescence in the benthic zone is less common. It has been attributed to the blockage of emitted light by a number of sources such as the sea floor, and inorganic and organic structures. Visual signals and communication that
7777-402: The ocean. A different effect is the thousands of square miles of the ocean which shine with the light produced by bioluminescent bacteria, known as mareel or the milky seas effect . Bioluminescence is abundant in the pelagic zone, with the most concentration at depths devoid of light and surface waters at night. These organisms participate in diurnal vertical migration from the dark depths to
7878-409: The only extant vertebrate whose notochord persists and is not integrated or replaced by the vertebral column. In the sturgeon the endoskeleton is of cartilage and the vertebral column consists of mostly vertebrae of cartilage, without vertebral centrums , supported by the retained notochord. Most vertebrates are aquatic and carry out gas exchange via gills . The gills are carried right behind
7979-441: The only unifying mechanism is the role of molecular oxygen ; often there is a concurrent release of carbon dioxide (CO 2 ). For example, the firefly luciferin/luciferase reaction requires magnesium and ATP and produces CO 2 , adenosine monophosphate (AMP) and pyrophosphate (PP) as waste products. Other cofactors may be required, such as calcium (Ca ) for the photoprotein aequorin , or magnesium (Mg ) ions and ATP for
8080-556: The open sea, including fish , jellyfish , comb jellies , crustaceans , and cephalopod molluscs; in some fungi and bacteria ; and in various terrestrial invertebrates, nearly all of which are beetles . In marine coastal habitats, about 2.5% of organisms are estimated to be bioluminescent, whereas in pelagic habitats in the eastern Pacific, about 76% of the main taxa of deep-sea animals have been found to be capable of producing light. More than 700 animal genera have been recorded with light-producing species. Most marine light-emission
8181-571: The oxidation of a specific compound, which he named luciferin , by an enzyme . He sent Harvey siphons from the mollusc preserved in sugar. Harvey had become interested in bioluminescence as a result of visiting the South Pacific and Japan and observing phosphorescent organisms there. He studied the phenomenon for many years. His research aimed to demonstrate that luciferin, and the enzymes that act on it to produce light, were interchangeable between species, showing that all bioluminescent organisms had
8282-466: The phenomenon. Today, the two prevailing hypotheses (both concerning marine bioluminescence) are those put forth by Howard Seliger in 1993 and Rees et al. in 1998. Seliger's theory identifies luciferase enzymes as the catalyst for the evolution of bioluminescent systems. It suggests that the original purpose of luciferases was as mixed-function oxygenases. As the early ancestors of many species moved into deeper and darker waters natural selection favored
8383-434: The photophores are within the animals oral reach, which leads researchers to suggest that it uses it bioluminescence to capture and lure prey. Fireflies use light to attract mates . Two systems are involved according to species; in one, females emit light from their abdomens to attract males; in the other, flying males emit signals to which the sometimes sedentary females respond. Click beetles emit an orange light from
8484-440: The predator itself more vulnerable by attracting the attention of predators from higher trophic levels. Grazing copepods release any phytoplankton cells that flash, unharmed; if they were eaten they would make the copepods glow, attracting predators, so the phytoplankton's bioluminescence is defensive. The problem of shining stomach contents is solved (and the explanation corroborated) in predatory deep-sea fishes: their stomachs have
8585-464: The pupae of the diamond back moth, Plutella xylostella has been demonstrated successful. It also has the pathogenic potential to kill the Asian corn borer , a pest of maize in east Asia, in 48 hours. Three species of Photohabdus have been found, which are Photorhabdus luminescens , Photorhabdus temperata and Photorhabdus asymbiotica . P. asymbiotica has been shown to be infectious to human, but
8686-591: The relationships between the Olfactores (vertebrates and tunicates) and the Cephalochordata. Amphioxiformes (lancelets) [REDACTED] Tunicata /Urochordata ( sea squirts , salps , larvaceans ) [REDACTED] Vertebrata [REDACTED] Vertebrates originated during the Cambrian explosion , which saw a rise in organism diversity. The earliest known vertebrates belongs to
8787-400: The retainment of functional eyes for organisms to detect bioluminescence. Organisms often produce bioluminescence themselves, rarely do they generate it from outside phenomena. However, there are occasions where bioluminescence is produced by bacterial symbionts that have a symbiotic relationship with the host organism. Although many luminous bacteria in the marine environment are free-living,
8888-480: The same species, such as to attract mates. In the laboratory, luciferase-based systems are used in genetic engineering and biomedical research. Researchers are also investigating the possibility of using bioluminescent systems for street and decorative lighting, and a bioluminescent plant has been created. Before the development of the safety lamp for use in coal mines, dried fish skins were used in Britain and Europe as
8989-644: The seabed. A vertebrate group of uncertain phylogeny, small eel-like conodonts , are known from microfossils of their paired tooth segments from the late Cambrian to the end of the Triassic. The first jawed vertebrates may have appeared in the late Ordovician (~445 mya) and became common in the Devonian period , often known as the "Age of Fishes". The two groups of bony fishes , the Actinopterygii and Sarcopterygii , evolved and became common. The Devonian also saw
9090-451: The size of a large pin's head". Charles Darwin noticed bioluminescence in the sea, describing it in his Journal : While sailing in these latitudes on one very dark night, the sea presented a wonderful and most beautiful spectacle. There was a fresh breeze, and every part of the surface, which during the day is seen as foam, now glowed with a pale light. The vessel drove before her bows two billows of liquid phosphorus, and in her wake she
9191-522: The source of light in dead wood. Tuckey , in his posthumous 1818 Narrative of the Expedition to the Zaire , described catching the animals responsible for luminescence. He mentions pellucids, crustaceans (to which he ascribes the milky whiteness of the water), and cancers (shrimps and crabs). Under the microscope he described the "luminous property" to be in the brain, resembling "a most brilliant amethyst about
9292-399: The strength of selection for antioxidation defense decreased as early species moved further down the water column. At greater depths exposure to ROS is significantly lower, as is the endogenous production of ROS through metabolism. While popular at first, Seliger's theory has been challenged, particularly on the biochemical and genetic evidence that Rees examines. What remains clear, however,
9393-633: The succeeding Carboniferous . Amniotes branched from amphibious tetrapods early in the Carboniferous period. The synapsid amniotes were dominant during the late Paleozoic, the Permian , while diapsid amniotes became dominant during the Mesozoic . In the sea, the teleosts and sharks became dominant. Mesothermic synapsids called cynodonts gave rise to endothermic mammals and diapsids called dinosaurs eventually gave rise to endothermic birds , both in
9494-411: The surface at night, dispersing the population of bioluminescent organisms across the pelagic water column. The dispersal of bioluminescence across different depths in the pelagic zone has been attributed to the selection pressures imposed by predation and the lack of places to hide in the open sea. In depths where sunlight never penetrates, often below 200m, the significance of bioluminescent is evident in
9595-407: The twentieth and early twenty-first century was published recently. In 1932 E. N. Harvey was among the first to propose how bioluminescence could have evolved. In this early paper, he suggested that proto-bioluminescence could have arisen from respiratory chain proteins that hold fluorescent groups. This hypothesis has since been disproven, but it did lead to considerable interest in the origins of
9696-402: The two classes). Tetrapods comprise the dominant megafauna of most terrestrial environments and also include many partially or fully aquatic groups (e.g., sea snakes , penguins , cetaceans). There are several ways of classifying animals. Evolutionary systematics relies on anatomy , physiology and evolutionary history, which is determined through similarities in anatomy and, if possible,
9797-487: The water column. These fish are able to utilize the longer wavelength to act as a spotlight for its prey that only they can see. The fish may also use this light to communicate with each other to find potential mates. The ability of the fish to see this light is explained by the presence of specialized rhodopsin pigment. The mechanism of light creation is through a suborbital photophore that utilizes gland cells which produce exergonic chemical reactions that produce light with
9898-449: The zooids, but each responds to the light produced by other individuals, and even to light from other nearby colonies. Communication by light emission between the zooids enables coordination of colony effort, for example in swimming where each zooid provides part of the propulsive force. Some bioluminous bacteria infect nematodes that parasitize Lepidoptera larvae. When these caterpillars die, their luminosity may attract predators to
9999-565: Was another ten years before he discovered the chemical's structure and published his 1957 paper Crystalline Cypridina Luciferin . Shimomura, Martin Chalfie , and Roger Y. Tsien won the 2008 Nobel Prize in Chemistry for their 1961 discovery and development of green fluorescent protein as a tool for biological research. Harvey wrote a detailed historical account on all forms of luminescence in 1957. An updated book on bioluminescence covering also
10100-423: Was bioluminescent as long as 540 million years ago. Bioluminescence is a form of chemiluminescence where light energy is released by a chemical reaction. This reaction involves a light-emitting pigment, the luciferin , and a luciferase , the enzyme component. Because of the diversity of luciferin/luciferase combinations, there are very few commonalities in the chemical mechanism. From currently studied systems,
10201-574: Was followed by a milky train. As far as the eye reached, the crest of every wave was bright, and the sky above the horizon, from the reflected glare of these livid flames, was not so utterly obscure, as over the rest of the heavens. Darwin also observed a luminous "jelly-fish of the genus Dianaea", noting that: "When the waves scintillate with bright green sparks, I believe it is generally owing to minute crustacea. But there can be no doubt that very many other pelagic animals, when alive, are phosphorescent." He guessed that "a disturbed electrical condition of
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