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Scientific terms translated


Abiota = non-living features of the environment, which can impact upon living organisms (Compared to "Biota")

Abyssopelagic Zone = aka Abyssal Zone, referring to the 2nd deepest layer of the ocean (between the "Hadalpelagic Zone" and "Bathypelagic Zone") from 4000 - 6000m depth (See also "Oceanic province")

[Ocean] Acidification = a process related to "climate change" whereby excess atmospheric carbon dioxide dissolves into the ocean, causing a drop in pH into acidic levels

Acoustic telemetry = scientific method to study shark movement by fitting them with electronic tags

Adelphophagy = see "Embryophagy"

Aggregation = when sharks form a group because environmental conditions (such as prey availability, temperature, salinity etc.) drive them to do so (In comparison to a "Social group")

Agonism / Agonistic display = any behaviour related to conflict or competition, including fighting, threat, defence, flight, freezing, avoidance and appeasement (See also "Threat display")

Alopiidae = family of sharks, order Lamniformes (aka Thresher sharks)

Amphistylic jaw suspension = primitive jaw morphology found in "Hexanchiformes", where upper jaw is attached to the "Chondrocranium" by ligaments, with limited support from cartilage. Hiders jaw protrusion and limits gape compared to "Orbitostylic" and "Euhyostylic jaw suspension"

Ampullae of Lorenzini = jelly-filled pores on the snout of "elasmobranchs" which are used to sense electromagnetic fields during hunting and navigation

Anacanthobatidae  = family of "Batoids", order "Rajiformes" (aka smooth skates)

Anal fin = "Median fin" on underside of a shark, near the "Cloaca", absent in the majority of "Squaliform" sharks

Angling = recreational and/or competitive (not commercial) shark fishing, using a rod and line. Once quite destructive, today sharks are commonly released unharmed and anglers contribute enormous amounts of data to scientific research

Anguilliform swimming = swimming via eel-like undulations of the whole body. Most inefficient mode of swimming employed by relatively sedentary species (Opposed to "Carangiform" and "Thunniform swimming")

Apex predator =  a predator at the top of a food chain; occupying the highest "Trophic level", with no (or very few) natural predators (See also "Mesopredator")

Aplacental viviparity = aka yolk-sac viviparity, see "Ovoviviparity"

Aplesodic pectorals = where radial cartilage extends into less than half of the pectoral fins, making them more flexible and less supportive (As opposed to "Plesodic pectorals")

Anoxic = term used describe an area of water devoid of any oxygen (See also "Hypoxic")

Arhynchobatidae = family of "Batoids", order "Rajiformes" (aka softnose skates)




Barbel(s) = sensory projections from near the nose / mouth in some shark species, used to detect prey

Bathypelagic Zone = aka the Midnight Zone, depth layer in the ocean between 1000 - 4000 m deep (lying between the "Abyssal zone" and the "Mesopelagic Zone"), with very little light penetration (See also "Oceanic province")

Batoids = skates and rays, close relatives of sharks, characterised by flattened body, ventral placement of gills and different fin morphology

Behavioural osmoregulation = movement to actively seek out site with preferred salinity range, minimising energetic costs associated with homeostatic "Osmoregulation"

Behavioural thermoregulation =  movement to actively seek out site with preferred temperature range

Benthic = bottom-dwelling, living on/close to "Substrate" (As opposed to “Pelagic”)

Biota = all living members of the environment, including flora and fauna (Compared to "Abiota")

Brachaeluridae = family of sharks, order "Orectolobiformes" (aka Blind sharks)

Breaching = leaping completely out of the water, seen in great white sharks, basking sharks, thresher sharks and mako sharks 

Buccal pumping = method of respiration, whereby the shark pumps its mouth open and closed to force oxygenated water over the gills, so it does not need to keep swimming in order to breathe (As opposed to "Ram ventilation")

Bucklers = thorn-like scales along the back and tail of skates 

Burleying = See "Chumming"

Bycatch = when non-target marine creatures are unintentionally caught during commercial fishing, an especially large threat to many shark species, responsible for largest volume of global shark mortality


Carangiform swimming = relatively efficient swimming method, used by active species, characterised by undulating only the back half of the body (Opposed to "Anguilliform" and "Thunniform swimming")

Carcharhindae = family of sharks, order "Carchariniformes" (aka Requiem sharks)

Carchariidae = family of sharks, order "Lamniformes" (aka sandtiger sharks)

Carchariniformes = order of sharks (families 1. Carcharindiae, 2. Scyliorhinidae, 3. Triakidae, 4. Sphyrnidae)

Carnivore = an animal that feeds on other animals (See "Herbivore" and "Omnivore")

Cartilage = resilient, flexible tissue which forms the skeleton of sharks, less mineralised and lighter than bone (creating buoyancy), and lacking nerves or blood vessels 

Catch-all fishing = commercial fishing operations composed of multiple gear-types (See "Gill net", Long-lining" and "Trawling"), to target a wide range of commercially valuable marine species for human consumption (As opposed to "Targeted fishing")

Caudal fin = aka the tail fin, provides propulsion for swimming 

Caudal peduncle = region on a sharks body from the base of the second dorsal fin to the start of the caudal fin

Centrophoridae =  family of sharks, order "Squaliformes" (aka gulper sharks)

Ceratotrichia = soft, unsegmented, flexible cartilage composed of keratin, providing support to the outer regions of a sharks fins, valued for shark fin soup

Cetorhinidae = family of sharks, order "Lamniformes" (aka Basking sharks)

Chlamydoselachidae = family of sharks, order "Hexanchiformes" (aka Frilled sharks)

Chondrichthyes / Chondrichthyans = class cartilaginous fishes; including sharks, rays and chimaeras (see "Holocephali"), with cartilaginous skeletons, skin made up of dermal denticles, 5-7 gill slits lacking boney covering, nostrils on underside (few exceptions), internal fertilisation using claspers and cloaca, revolver dentition, urea for osmoregulation, lacking swim bladders and boney scales

Chondrocranium = cartilaginous structure protecting and providing support for the brain and sensory organs in sharks, made of single, unsutured structure

Chumming = aka burleying, the act of attracting sharks to a boat by tossing liquidated fish tissues and oil into the water to create an odour plume

Circle hook = type of "long-lining" hook which is relatively easy to remove from a shark's mouth in order to safely release them after accidental "bycatch" (As opposed to "J Hook")

CITES (Convention on International Trade in Endangered Species of Flora and Fauna)  =  an agreement between 183 signatory nations to ensure that international trade in specimens of wild animals and plants does not threaten their survival. Meeting every three years at a conference of parties (CITES COPs), to debate additions of endangered species to Appendix II (controlling and limiting international trade) and Appendix I (banning all international trade)

Cladodonts = earliest known true sharks, which arose around 150 million years ago and were killed off in the Great Permian extinction e.g Cladoselache, Xenacanthus, Falcatus (See also "Hybodont")

Clasper[s] = aka "Mixopterygia", modified fins of male sharks, used as reproductive organs to transfer sperm during mating (See also "Cloaca")

Classical conditioning = a learning process whereby an animal learns to associate one stimulus with another, e.g. the sound of a bell with food (see also "Operant conditioning")

Climate change = term used to describe the anthropogenically driven change in global climate, caused by excess Greenhouse gas emissions, predicted to cause rising sea levels, shifts in ocean cycling, and ocean "Acidification" and "Deoxygenation", and may lead to "climate-induced range shifts"

Climate-indiced range shift = when a species is forced to alter their natural distribution in response to shifting environmental conditions (commonly temperature changes) thanks to anthropogenically-induced "climate change" 

Cloaca = female reproductive opening for mating and also for defecation (See also "Clasper")

CMS (Convention on Migratory Species) = aka The Bonn Convention, international agreement that aims to conserve migratory species within their entire range, rather than via legislation in every separate country

Cognition = the mental process of gaining knowledge and adapting behaviour, through thought, experience and the senses

Conspecific = another individual of the same species (As opposed to "Heterospecific")

Continental shelf = rim of continent covered by sea, from coast to 200 m depth, where seafloor begins to slope down to deepsea planes (See also "Neritic Province")

Continental slope = part of seafloor sloping down from border of "Continental shelf" at 200 m, down to deepsea planes of 4000 m depth (See also "Oceanic Province")

Continuous breeding = year-round breeding with no resting phase between pregnancies, where females develop eggs throughout pregnancy in preparation for the next mating. Characteristic of "Viviparous" sharks with minimal maternal input, eg. deep-sea "Squaliforms" (As opposed to "Seasonal" and "Punctuated breeding")

Convergent evolution = the phenomenon whereby organisms which are not closely related, independently evolve similar traits, as they adapt to similar environments or "Niches"

Countershading = fading of skin pigmentation from dark on the "Dorsal" side to light on the "Ventral" side, making the animal more difficult to see in the water

Crepuscular = an animal appearing or active in twilight; just before the sun goes down, or just after the sun rises

Critically Endangered = highest "IUCN Red List" "threatened category", used to flag that a species has a seriously high risk of extinction in the wild (See also "Not Evaluated", "Data Deficient",  "Least Concern", "Near Threatened", "Vulnerable", "Endangered")


Dalatiidae = family of sharks, order "Squaliformes" (aka kitefin sharks)

Dasyatidae = family of "Batoids", order "Myliobatiformes" (aka whiptail stingrays) 

Data Deficient = "IUCN" "Red List" category assigned to a species when (whilst we may have in-depth knowledge about their ecology / distribution / life history etc.) we have limited data to assess whether their populations are at risk of extinction in the wild (See also "Not Evaluated", "Least Concern", "Near Threatened", "Vulnerable", "Endangered", "Critically Endangered")

Delayed oviparity = aka retained oviparity, reproductive method whereby eggs are laid some time after internal fertilisation and therefore spend a relatively short period developing outside of the mother, and are a relatively costly investment to the female (As opposed to "Immediate oviparity")

[Ocean] Deoxygenation = a process related to "Climate change", whereby rising sea surface temperatures causes oxygen to escape from seawater

Dermal denticles = aka "Placoid scales", plate-like scales which form shark skin, evolved from teeth

Display = a stereotyped behaviour pattern, modified by natural selection, to convey information, usually among "Conspecifics" or within social groups 

Dissection = the examination of internal structures of an animal, in order to better understand its anatomy

Dominion = an area where an individual exhibits elevated dominance and aggression towards others, but does not attempt to expel them

Dorsal = referring to the back of an animal (As opposed to "Ventral")

Dorsal fin(s) = "median fins" on the back of a shark, which act as a keel (improving manoeuvrability and preventing tipping from side-to-side whilst swimming). Presence / loss of 2nd dorsal fin can be used to identify relatedness of shark species 

Dredging = commercial fishing method whereby heavy apparatus are dragged along the ocean floor to extract valuable bottom-dwelling species (See "Trawling")

Dynamic lift = type of upwards force created by fins whilst swimming (As opposed to "Static lift")


Echinorhinidae = family of sharks, order "Squaliformes" (aka Bramble sharks)

Echinorhiniformes = order if sharks (family 1. Echinorhinidae)

Ecosystem = a community of interacting organisms and their physical environment

Ectothermy / Ectotherm = an animal which does not raise its internal body temperature above that of its surroundings (As opposed to "Endothermy"

Elasmobranch / Elasmobranchii = aka Euselachii, subclass; collective term for sharks and rays, named for arch-shaped gills

Embryophagy = form of "Intrauterine cannibalism" whereby unborn pups eat their siblings in the womb

Embryotrophy = reproductive method unique to tiger sharks, where unborn pups are enclosed in sacs of fluid which provide them nutrition  

Endangered = second highest "IUCN" "Red List" "threatened category" used to flag that a species has a high risk of extinction in the wild  (See also "Not Evaluated", "Data Deficient",  "Least Concern", "Near Threatened", "Vulnerable", "Critically Endangered")

Endothermy / Endotherm = an animal which raises its internal body temperature higher than the surrounding environment (As opposed to "Ectothermy"), differs from "Mesothermy" as temperature is maintained within a homeostatic range (See also "Regional endothermy")

Epipelagic Zone = aka Sunlight zone, shallowest layer of the ocean, which light can penetrate, from the surface up to 200m depth (above the "Mesopelagic Zone")

Etmopteridae = family of sharks, order "Squaliformes" (aka lantern sharks)

Euhyostylic jaw suspension = highly evolved jaw morphology found in the "Batoids" , where there are no connections (via either ligaments or articulation) between the "Chondrocranium" and upper jaw, and jaws are supported entirely by cartilage. Allowing extreme upper jaw protrusion and wide gape, compared to "Amphistylc", "Orbitostylic-" and "Hyostylic jaw suspension"

Euryhaline = able to exploit a wide range of salinities (As opposed to "Stenohaline"), rare in "Elasmobranchs"

Euselachii = see "Elasmobranchii"

Extant = living species (As opposed to "Extinct")

Extinct = species with no living individuals (As opposed to "Extant")


Facultative parthenogenesis = the ability of some sexually reproducing animals to switch to asexual reproduction. May be linked to "Inbreeding"

Familya term used describe a group of "Genera" in  taxonomic classification

Fecundity = the number of offspring which can be produced by a female throughout her life, often relatively low in sharks

[Shark] Finning = wasteful and cruel type of commercial shark fishing where fins are removed and the rest of the carcass is discarded at sea. Now illegal in many countries, controlled by "fins naturally attached" and "fins to carcass ratio" policies

Fins naturally attached policy = legislation implemented to control and monitor shark "finning", whereby fishers are required to land shark carcass with fins attached (As opposed to "Fins to Carcass Ratio Policy")

Fins to carcass ratio policylegislation implemented to control and monitor shark "finning", whereby fishers are required to land the correct number/weight of carcasses to match the amount/weight of detached fins onboard (As opposed to "Fins naturally attached policy")

Fish Aggregation Device (FAD) = device used in commercial fishing, (especially "Purse seine" fishing), to encourage fish into a tight group, making them easier to catch. Previously non-destructive to sharks, modern, complex raft designs have increased shark "Bycatch"

[Shark] Fishing = extracting sharks from the marine environment for human consumption of fins, meat and/or liver oils. Can be "commercial"or subsistence (for use by the fisher to feed their family) (Not to be confused with "Finning")

Fitness = an individual's ability to survive to reproductive age, find a mate, and produce offspring

Flagship species = conservation biology concept that employs the popularity of a charismatic species as a symbol that may also ensure the protection of other less-popular species 

Following behaviour = copulation behaviour seen in some species, male following female with snout less than 30cm from tail


Galeocerdidae = family of sharks, order "Carcharhiniformes" (aka tiger shark)

Galeomorphii / Galeomorphs = superorder, galeomorph sharks (Orders 1. Heterodontiformes, 2.  Orectolobiformes, 3. Lamniformes, 4. Carchariniformes) (As opposed to "Squalomorphs")

Gaping = an "agonistic" behaviour of slow, exaggerated opening of the jaws conspicuously wider than normal

Genetic bottleneck = when the genetic diversity of a population is reduced due to "Inbreeding", making a species vulnerable to disease 

Genus (pl. Genera) = a term used describe a group of species in  taxonomic classification, referring to a set of closely related or similar species 

Ghost fishing = discarded, lost or abandoned, fishing gear in the marine environment, which continues to entangle and potentially kill marine animals, smother habitats (such as reefs) and act as a hazard to navigation

Gill(s) = slit-like openings on each side of a shark's head, used to extract oxygen from water for respiration

Gillnet = commercial fishing method, utilising a net which entangles in fish gills (In contrast to a "Purse seine"), difficult to untangle sharks caught as "Bycatch", so can lead to "Post-release mortality"

Gill rakers = small cartilaginous projections from the gill arch, which form a finger-like sieve, used in filter-feeding

Ginglymostomatidae = family of sharks, order "Orectolobiformes" (aka nurse sharks)

Glaucostegidae = family of "Batoids", order "Rhinopristiformes" (aka giant guitarfishes)

Gnathostome = term used to refer to any and all fish (including sharks) with an articulated jaw

Golden Age of Sharks = period 300 - 360 million years ago (during the Carboniferous) when sharks were the dominant fish in the ocean and their biodiversity was incredibly high

Gravid = carrying eggs or young, aka pregnant

Gurgesiellidae = family of "Batoids", order "Rajiformes" (aka pygmy skates)

Gymnuridae = family of "Batoids", order "Myliobatiformes" (aka butterfly rays)


Hadalpelagic Zone = aka Deep-Sea Trenches, the deepest layer of the oceans (below the "Abyssopelagic Zone") at depths of 6000m or more (See also "Oceanic province")

Hemigalaidae = family of sharks, order "Carcharhiniformes" (aka weasel sharks)

Hemiscyllidae = family of sharks, order "Orectolobiformes" (aka  longtailed carpet sharks)

Herbivore = an animal that feeds on plants (See "Omnivore" and "Carnivore"

Heterocercal tail = tail with upper and lower caudal lobes of differing size and/or shape (As opposed to "Homocercal" or "Hypocercal tail")

Heterodont dentition = jaws having teeth of different shapes (As opposed to "Homodont dentition"

Heterodontidae = family of sharks, order "Heterodontiformes" (aka horn sharks)

Heterodontiformes = order of sharks (family 1. Heterodontidae)

Heterotroph = organisms which rely upon consuming other organisms (plants and/or animals) for nutrition (As opposed to a "Carnivore", "Herbivore", "Omnivore")

Hexanchidae = family of sharks, order "Hexanchiformes" (aka Cow sharks)

Hexanchiformes = order of sharks (families 1. Hexanchidae, 2. Chlamydoselachidae)

Hexatrygonidae = family of "Batoids", order "Myliobatiformes" (aka sixgill stingrays)

Histotrophy = where embryos of "Viviparous" species, are nourished by the secretion of mucous (known as histotroph) from the lining of the mother's uterus. Relatively costly to mother compared to "Lecithotrophy" and "Limited histotrophy" (See also "Lipid histotrophy" and "Placental viviparity")

Holocephali = aka chimaeras, close relatives of sharks and rays, now a small group, but which were once very biodiverse

Homeostasis = the maintenance of a constant internal environment within the body, despite fluctuating external conditions. In sharks this includes the maintenance of internal temperature, and salt, ion and water levels in the body (See "Osmoregulation")

Homocercal tail = tail with symettrical upper and lower caudal lobes (As opposed to "Heterocercal" and "Hypocercal tails")

Homodont dentition = jaws with teeth of the same shape (As opposed to "Heterodont dentition"

Hunch display = "Agonistic" behaviour exhibited by sharks, part of series of stereotyped movements preceding aggressive attack, featuring raised snout, arched back, lowered pectoral fins and exaggerated swimming movements 

Hybodonts = group of shark ancestors which arose after the extinction of the "Cladodonts" during the Great Permian extinction and gave rise to modern sharks (See also "Neoselachians")

Hyostylic jaw suspension = jaw morphology found in most "Elasmobranchs" and all bony fishes, where loose ligament and cartilage connection between the jaw and "Chondrocranium", allows wider protrusion and gape than "Amphistylic" and "Orbitostylic", but less than and "Euhyostylic jaw suspension"

Hypnidae = family of "Batoids", order "Torpediniformes" (aka electric rays)

Hypocercal tail = unusual tail morphology found in angel sharks, where lower caudal fin lobe is larger then the upper, causing head elevation (As opposed to "Heterocercal" and "Homocercal tails") 

Hypoxia / Hypoxic = term used to describe an area of water which is extremely low in dissolved oxygen (See also "Anoxic")


Idiosphere = the volume of space immediately surrounding an individual, that it will defend if broached without appropriate signalling or permission

Immediate oviparity = aka single oviviparity, reproductive method whereby eggs are laid very quickly after internal fertilisation, so spend a long time developing outside of the mother where they are vulnerable to predation (Opposed to "Delayed oviparity)

Inbreeding = when closely related species breed together, leading to a "Genetic bottleneck"

Innate = aka instinct, knowledge or behaviours present since birth, which do not require learning or experience 

Inshore = term used to describe the region of ocean close to the  land; from the surf zone up to 50 metres depth (As opposed to "Offshore", See also "Neritic Province")

Intertidal zone = region of the ocean close to shore which is influenced by the tides; submerged at high tide and exposed at low tide. Shallower section of the "Epipelagic Zone" compared to the "Sublittoral Zone" (See also "Neritic Province")

Intrauterine cannibalism = when unborn pups feed on their siblings and/or unfertilised eggs (See "Adelphophagy", "Embryophagy", "Oophagy"

Internal fertilisation = reproduction through insertion of the male sex organ into female genitalia (compares to external fertilisation, aka spawning, used by most fish)

IUCN (International Union for the Conservation of Nature) = organisation assessing abundance of species of wild animals to assign them to an extinction risk category ("Not Evaluated", "Data Deficient", "Least Concern", "Near Threatened", "Vulnerable","Endangered", "Critically Endangered") on the "Red List" of threatened species

IUCN SSG (International Union for the Conservation of Nature Shark Specialist Group) = group of specialists within the IUCN who assess sharks and their relatives for the "Red List" of threatened species


Jaw closing = an "agonistic" behaviour of non-forcefully bringing the jaws together

[the] Jaws Effect = term coined by Dr C. Neff to describe the pervasive fear of sharks (leading to revenge cullings and inadequate conservation measures) in the wake of the 1975 blockbuster movie

J hook = type of "long-lining" hook which is often be swallowed, so is relatively difficult to remove and can lead to "at-vessel" or "post-release mortality" after "bycatch" (As opposed to "Circle Hook")

[the] Jurassic Split = now inaccurate term previously used to describe the moment when sharks and rays diverged, originally thought to be some 200 million years ago (during the Jurassic period), now known to have occurred some 270 million years ago

Juvenile = a young animal which has yet to reach sexual maturity


Keystone species = a species which is critical to an ecosystem, without which the system would collapse completely

Klinotaxis = side-to-side motion of the head in response to  stimulation (commonly a smell), allowing orientation and movement towards the stimulus by alternating exposure of sensory receptors on either side of the body (See also "Tropotaxis")

-Selected life history strategy = term use describe species (including all sharks) which are slow growing, mature late in life and have low "Fecundity", meaning they are slow to recover from population declines (As opposed to "r-Selected life history strategy")


Lamnidae = family of sharks, order "Lamniformes" (aka Mackerel sharks), including only known "Endothermic" shark species 

Lamniformes = order of sharks (families 1. Lamnidae, 2. Mitsukurinidae, 3. Megachasmidae, 4. Cetorhinidae, 5. Alopiidae, 6. Odontaspididae)

Lateral keel = prominent ridges along the sides of some sharks, which provide stability when swimming at high speeds

Lateral line = sensory organ running parallel along each side of a fish's body, allowing detection of water displacement and changes in pressure (See "Mechanoreception")

Least Concern = "IUCN" "Red List" category, used to flag that a species is not at risk of extinction in the wild (See also "Not Evaluated", "Data Deficient", "Near Threatened", "Vulnerable", "Endangered", "Critically Endangered")

Lecithotrophy / Lecithotrophic = form of "Ovoviparity" where  developing embryos receive nutrition exclusively from yolk. Relatively less costly to the mother compared to "Matrotrophy". Similar to "Oviparity"

Lekking = when individuals of one sex (commonly males) group to perform mating rituals, displaying competitively to the opposite sex their readiness to mate and value as a breeding partner

Leptochariidae = family of sharks, order "Carcharhiniformes" (aka barbeled houndsharks)

Limited histotrophy = when embryos of "Ovoviviparous" sharks are nourished via mucoid secretions from the mother's uterine wall. Relatively, costly to mother compared to "Lecithotrophy", but less costly than "Histotrophy"

Lipid histotrophy = when embryos of "Viviparous" species are nourished with uterine milk without direct connection to the uterine wall (In comparison to "Placental viviparity". See also "Histotrophy")

Longevity = the length of an organism's life, ranges enormously in sharks from a few decades in some smoothhounds, up to 600 years in the Greenland shark 

Longlining / Long-line fishing = commercial fishing method utilising a line with multiple (maybe thousands) of baited hooks at regular intervals. Relatively less destructive method than "Gill nets", with reduced "Post-release mortality" of sharks caught as "Bycatch"

Looping = an "Agonistic" display of swimming in a spiral loop


Marine Protected Area (MPA) = an area managed to protect marine ecosystems, processes, habitats, and species, which can contribute to the restoration and replenishment of resources for social, economic, and cultural enrichment

Mate choice = when choice of a reproductive partner is non-random, but rather based on favourable traits. Commonly 'female mate choice' (when female chooses male), but also sometimes 'male mate choice' (when male chooses female) or 'mutual mate choice' (when both male and female choose each other) (See also "Sexual selection")

Matrotrophy / Matrotrophic = form of reproduction where developing embryos gain nutrition from the mother. Costly to the mother compared to "Lecithotrophy")

Mechanoreception = sensory ability to detect displacements in water (See "Lateral line")

Median fins = unpaired fins along the centre line of a sharks body, which provide stability, eg. "Dorsal fin(s)" and "Anal fin"

Megachasmidae = family of sharks, order "Lamniformes" (aka Megamouth sharks)

Megalodon = common name used to refer to an enormous, extinct shark species OtodusCarcharocles megalodon

Mermaid's purse = slang term used for shark / ray egg cases (See "Oviparity")

Mesopelagic zone = aka Twilight Zone, relatively shallow depth layer in the ocean, from 200 - 1000 metres (between the "Epipelagic Zone" and "Bathypelagic Zone"), where light can penetrate (See also "Oceanic province")

Mesopredator = a mid-ranking predator (below the "Apex predator") in the mid-  "Trophic levels", which typically preys on smaller animals, but is itself prey to larger predators

Mesothermic / Mesotherm = a relatively rare form of "Endothermy" whereby an organism elevates its body temperature above that of the environment using metabolic heat, but has little to no control to maintain a specific temperature range

Microplastics = extremely small pieces of plastic debris polluting the oceans, from the breakdown of discarded consumer products and industrial waste

Mitsukurinidae = family of sharks, order "Lamniformes" (aka Goblin sharks)

Mixopterygia = See "Claspers"

Mobulinae = subfamily of "Batoids", family "Myliobatidae", order "Myliobatiformes" (aka manta rays, devil rays)

Monophyletic group = a group of organisms which have all evolved from a common ancestor

Mouthing = hunting and/or investigative behaviour; whereby shark grasps an object in it’s mouth briefly, releasing it without removing flesh

Multiple paternity = when a female carries offspring from more than one father at once (See also "Polyandry")

Myliobatidae = family of "Batoids (including several subfamilies), order "Myliobatiformes" (see also "Myliobatinae", "Mobulinae", "Rhinopterinae")

Myliobatinae = subfamily of "Batoids", family "Myliobatidae", order "Myliobatiformes" (aka eagle rays)

Myliobatiformes = order of "Batoids" (families "Dasyatidae", "Gymnuridae", "Hexatrygonidae", "Myliobatidae", "Plesiobatidae", "Potamotrygonidae", "Urolophidae", "Urotrygonidae")


Narcinidae = family of "Batoids", order "Torpediniformes" (aka numbfishes)

Nares = aka nostrils, channels that lead into the "Olfaction" organs

Natal site = place of birth (often referred to in terms of "Philopatry")

Natural selection = the process whereby organisms better adapted to their environment tend to survive and produce more offspring

Near Threatened = "IUCN" "Red List" category, used to flag that a species is not threatened with extinction,  but further population depletions could make it so  (See also "Not Evaluated", "Data Deficient",  "Least Concern", "Vulnerable", "Endangered", "Critically Endangered")

Negative buoyancy = when an animal is heavier than surrounding water and tends to sink. In sharks this is counteracted by their oily liver, light skeleton, lift generated by fins when swimming and, in some species, by gulping air from the surface (See also "Neutral buoyancy", "Dynamic-" and "Static lift")

Neonate = a new-born animal

Neoselachii / Neoselachian = subcohort of the "Euselachii", modern sharks and rays, including the "Squalimorphs", "Galeomorphs" and "Batoids"

Neritic Province = term used to refer to the shallow part of the ocean (up to 200 metres depth), near the coast, overlying the "Continental Shelf". Includes the "Inshore" and "Offshore" regions (As opposed to the "Oceanic Province")

Neutral buoyancy = when an animal is neither more or less buoyant than surrounding water, and hangs in the water column without sinking or floating (See also "Negative buoyancy")

Niche = aka ecological niche, the position of a species within an ecosystem and its ecological role within that system

Nictiting membrane = whitish membrane which can be drawn across the eye to for protection, present only in "Carcharhiniformes"

Noise pollution = anthropogenic sound (from drilling, seismic surveys, shipping, radar and sonar) which causes disturbance in the marine environment

No-take reserve = type of "Marine Protected Area" where any and all fishing is banned

Not Evaluated = "IUCN" "Red List" category assigned to a species with has yet to be assessed by experts to determine whether they are/are not at risk of extinction in the wild  (See also "Data Deficient",  "Least Concern", "Near Threatened", "Vulnerable", "Endangered", "Critically Endangered")

Nursery habitat = area where juvenile marine animals live during the first months of life because the habitat offers ample food and/or protection from predators (See also "Philopatry")

Nutrient translocation = the movement of nutrients from one location to another, for example, from a feeding site to a defecation site


Obligate ram ventilator = a species of shark that must keep swimming forwards to be able to breathe and cannot ventilate via "Buccal pumping"

Oceanic Province = term used to refer to the deeper parts of the ocean (deeper than 200 metres), overlying the "Continental Slope" and abyssal plains.  (As opposed to the "Neritic Province")

Odontaspididae = family of sharks, order "Lamniformes" (aka Sandtiger sharks)

Offshore = term used the describe the region ocean which is away from the coast; from 50 metres up to 200 metres depth (As opposed to "Inshore", See also "Neritic Province")

Olfaction = the sense of smell

Omnivore = an animal that eats a variety of food of both plant and animal origin (See "Herbivore" and "Carnivore")

Ontogeny / Ontogenetic =  the developmental history of an organism

Oophagy / Oophagus =  aka "Intrauterine cannibalism", when embryos feed on unhatched eggs while still inside the mother's uterus (See also "Adelphophagy")

Operant conditioning = learning process whereby an animal learns to associate an action with either a positive (reward) or a negative (punishment) response (See also "Classical conditioning")

Orbitostylic jaw suspension = evolutionarily quite advanced jaw morphology, where the short orbital process of upper jaw buttresses the jaw. Provides intermediate protrusion and gape compared to "Amphistylic" and "Euhyostylic jaw suspension"

Order = a term used describe a group of "Families" in  taxonomic classification 

Orectolobidae = family of sharks, order "Orectolobiformes" (aka wobbegongs)

Orectolobiformes = order of sharks (families 1. Orectolobidae, 2. Rhincodontidae, 3.Stegostomatidae, 4. Parascyllidae, 5. Hemiscyllidae, 6. Brachaeluridae, 7. Ginglymostomatidae)

Osmoregulation = the maintenance of stable ion, salt and water concentrations within the body, by counteracting the natural tendency for water to diffuse from areas of high to low salt ie. by stopping the loss of water in very saline environments and stopping movement of water into the body in less saline water (One facet of "Homeostasis")

Otolith[s] = carbonate structures in the ears of some fish, which can be used to estimate age (See also "Stataconia")

Oviparous / Oviparity = egg-laying reproductive method, with embryos nourished by egg yolk (As opposed to "Ovoviviparity" and "Viviparity")

Ovoviviparous / Ovoviviparity = aka Aplacental viviparity aka Yolk-sac viviparity, reproduction whereby fully developed young hatch from an egg within the uterus and are birthed soon after, embryos are nourished by yolk and not supplied nutrients via a placenta (As opposed to "Oviparity" and "Viviparity") (See also "Immediate-" and "Delayed oviparity")

Oxynotidae = family of sharks, order "Squaliformes" (aka rough sharks)


Paired fins = fins found symmetrically in twos,  corresponding to the fore and hind-limbs in mammals, eg. "Pectoral ins" and "Pelvic fins" in sharks

Palatoquadrate protrusion = forward extension of the upper jaw, causing it to separate from the cranium and which may bare the upper teeth. Exaggerated in the goblin shark - extending their reach when hunting prey

Parascyllidae = family of sharks, order "Orectolobiformes" (aka collared carpet sharks)

Parthenogenesis = when a female spontaneously switches to asexual reproduction and produces offspring without a male

Parturition = the process of giving birth to offspring

Parturition habitat = environment where females give birth to their young

PAT Tag = aka Pop-Up Archival Tag, type of electronic tag, used to study movement, which automatically detaches from the shark for data download

Pectoral fin(s) = "Paired fins" found on the either side of a sharks body (homologous to the fore-limbs in mammals), used for orientation and to create "Dynamic lift" (See "Pitch" and "Roll"), and for communication in "Agonistic displays". Can be either "Plesodic" or "Aplesodic"

Pelagic = living in open water (As opposed to “Benthic”)

Pelvic fins = "Paired fins" located on the underside of a shark (homologous to the hind-limbs in mammals), which prevent "Roll" and control "Pitch"

Pentachidae = family of sharks, order "Carcharhiniformes" (aka deepsea catsharks)

Periocardio-peritoneal canal = space connecting area around the heart to the rest of the abdomen, aiding in heart function and important for avoiding heart compression 

Philopatry =  the tendency of animals  to return / remain near a particular site / area, sometimes returning to a remarkably specific location even after extended, long-distance migrations

Photophore = a light-producing organ in the skin

Phytoplankton = microscopic "Planktons" floating in the water column, which produce energy via photosynthesis, rather than ingestion of other organisms. Vital food source for many marine animals at low "Trophic levels" (See also "Zooplankton")

Pineal organ / Pineal gland = organ located near the brain, involved in photoreception independently from the eyes, by receiving light through the top of the head. Produces melatonin to maintain a circadian rhythm 

Pitch = up and down angle-of-swimming in the water (See also "roll" and "yaw")

Pit organs = unspecialised sensory cells on the top and sides of the head, around the spiracles, and along the trunk and tail, which detect external water movement

Placental viviparity = reproduction whereby live young are birthed after having been nourished with uterine milk directly via a placenta-like structure connected to the mother's uterine wall. Very costly to the mother compared to other reproductive methods (As opposed to "Lipid histotrophy", "Aplacental viviparity". See "Viviparity")

Placoid scales = See "Dermal denticles"

Plankton = small or microscopic organisms (mostly diatoms, protozoans, small crustaceans, and the eggs and larval stages of larger animals) drifting in the water column. Vital food source for many marine animals at low "Trophic levels" (See also "Phytoplankton" and "Zooplankton")

Platyrhinidae = family of "Batoids" (aka thornback rays), thought to be in the order "Rhinopristiformes", but this is disputed

Plesiobatidae = family of "Batoids", order "Myliobatiformes" (aka deepwater stingrays)

Plesodic pectorals = evolutionarily advanced pectoral fin morphology, where radial cartilage spreads into more than half of the fin, making them stiffer (As opposed to "Aplesodic pectorals")

Poikilothermic / Poikilotherm = an organism with a variable body temperature that tends to fluctuate with the temperature of its environment

Polyandry = when one animal mates with multiple partners and becomes pregnant with several different fathers (aka "Multiple paternity")

Polyphyodont dentition = aka "revolver dentition", whereby an animals teeth are continually replaced throughout life

Post-release mortality = death after release from a fishery due to injury / stress / infection / behaviour changes

Potamotrygonidae = family of "Batoids", order "Myliobatiformes" (aka river stingrays)

Precaudal pit = small notch before the caudal fin in some species of sharks which increases tail flexibility

Principal population = main breeding population of migratory sharks (As opposed to "Accessory population")

Prismatic calcified cartilage = form of shark cartilage which is hardened by calcium to make the bones more resilient to stress at certain regions

Pristidae = family of "Batioids, Order "Rhinopristiformes" (aka sawfishes / carpenter sharks) (not to be confused with "Pristiophoridae") 

Pristiophoridae = family of sharks, order "Pristiophoriformes" (aka saw sharks)

Pristiophoriformes = order of sharks (family 1. Pristiophoridae)

Proscyllidae = family of sharks, order "Carcharhiniformes" (aka finback catsharks)

Pseudocarchariidae = family of sharks, order "Lamniformes" (aka crocodilee shark)

Pseudotriakidae = family of sharks, order "Carcharhiniformes" (aka false catsharks)

Punctuated breeding = reproductive method where female is pregnant (often for one year or more) and is then dormant for an extended period in order to recover, making for long reproductive cycles. Common in "Viviparous" sharks where maternal input is high eg. dusky sharks (As opposed to "Continuous" or "Seasonal breeding")

Punting = form of locomotion used by "skates", where bi-lobed pelvic fins are used to crawl along the benthos

Pup = term used to describe shark offspring

Purse seine = commercial fishing method targeting dense schools of fish, utilising a basket-shaped net that surrounds them from all sides. Relatively non-destructive method, except when including a "Fish aggregating device", which increases shark "Bycatch" (See also "Longlining" & "Gillnet")


Rajidae = family of "Batoids", order "Rajiformes" (aka skates)

Rajiformes = order "Batoids" (families "Anacanthobatidae", "Arhynchobatidae", "Gurgesiellidae", "Rajidae")

Raking = an agonistic behaviour of forcefully striking of the upper jaw teeth against a "Con-/ Hetero-specific", causing injury to the receiver 

Ramming = an "Agonistic" display where a signaller uses it’s snout to forcefully strike a receiver, often causing retreat 

Ram ventilation = method of respiration, whereby the shark swims forwards to keep oxygenated water running over the gills (As opposed to "Buccal pumping". See also "Obligate Ram Ventilator")

Recruitment = term used to describe juvenile animals surviving to maturity and becoming a part of the adult population

Rectal gland = small organ responsible for maintaining osmotic "Homeostasis", by eliminating excess sodium and chloride ions which diffuse into a shark's body from salt water (See "Osmoregulation")

Red List [of Threatened Species] = List of wild species threatened with extinction, produced by the "IUCN" (See also "Vulnerable","Endangered", "Critically Endangered")

Red muscle = highly vascularised, slow-twitch muscle used for slow, cruising swimming in sharks. Contractions generate heat in sharks with "Regional endothermy"  (As opposed to "White muscle")

Regional endothermy = "Endothermy" limited to only certain areas of the body, such as vital organs like the eyes, brain and muscles. Found in "Lamniform" sharks

Repetitive aerial gaping (RAG) = an agonistic behaviour (potentially due to frustration) consisting of rhythmic, exaggerated opening and closing of the jaws above the water surface, known only in white sharks 

Retia mirabella = countercurrent heat-exchangers found in sharks of the "Lamniform" family, which are responsible for "Endothermy" 

RFMOs (Regional Fisheries Management Organisations) =  international organisations regulating regional fishing activities in the high seas by achieving cooperation between multiple nations which all interact with one stock, specifically ICCAT (The International Commission for the Conservation of Atlantic Tunas), IATTC (The Inter-American Tropical Tuna Commission), WCPFC (The Western & Central Pacific Fisheries Commission) and IOTC (The Indian Ocean Tuna Commission) deal with sharks 

Rheotaxis = the ability to orient with or against the current, thanks to the  detection of water flow

Rhincodontidae = family of sharks, order "Orectolobiformes" (aka Whale sharks)

Rhinidae = family of "Batoids", order "Rhinopristiformes" (aka wedgefishes)

Rhinobatidae = family of "Batoids", order "Rhinopristiformes" (aka guitarfishes)

Rhinopristiformes = order of "Batoids" (families "Glaucostegidae", "Pristidae", "Rhinidae", "Rhinobatidae", Trygonorrhinidae"  and possibly "Platyrhinidae", "Zanabatidae")

Rhinopterinae = subfamily of "Batoids", family "Myliobatidae", order "Myliobatiformes" (aka cownose rays)

Revolver dentition = "Polyphyodont dentition", teeth embedded into gums (rather than jaw, as seen in bony fish) and are continuously replaced throughout life

Rhincodontidae = family of sharks, order "Orectolobiformes" (aka whale shark)

Roll = body positioning on a horizontal plan in the water (See also "Pitch" and Yaw")

Rostral teeth = hardened tooth-like structures projecting from the extended rostrum in sawfish and sawsharks

Rostrum = the snout of a shark, which projects out from the head

r  -Selected life history strategy = term used to describe species, like rabbits, which grow quickly, reach maturity at a young age and have high "Fecundity" (As opposed to "K-Selected life history strategy")


Salinity = measure describing the amount of salt dissolved in seawater

Scavenger = an animal which exploits food which available (due to another predator's hunting or natural mortality) without hunting the prey themselves

Scyliorhinidae = family of sharks, order "Carchariniformes" (aka Cat sharks)

Seasonal breeding = when reproduction is limited to certain times of year. Common in "Ovoviviparous" sharks and rays (As opposed to "Continuous" or "Punctuated breeding")

Secondary lamellae = sites of gas exchange (oxygen in and carbon dioxide out) in the "Gills"

Sexual dimorphism = differences between males and females of a species, including differences in size, colour or behaviour

Sexual Selection = "natural selection" occurring due to preferences of sexual partners for certain features (See also "Mate choice"). Jokingly called 'survival of the sexiest'

Siphon sac = male reproductive organ in sharks, which fills with seawater to flush sperm into the female during mating

Skate[s] = see "Rajiformes"

Somniosidae = family of sharks, order "Squaliformes" (aka Greenland shark)

Species = a term used in  taxonomic classification, referring to a group of individuals which are capable of reproducing together

Sperm storage = reproductive strategy employed by females of some species, where viable spermatozoa are stored for an extended period of time after mating, so the female can become pregnant at a later date

Sphyrnidae = family of sharks, order "Carchariniformes" (aka hammerhead sharks)

Spiracle(s) = a pair of vestigial gill slits behind the eye of some sharks, used to provide oxygenated blood directly to the eye and brain through separate vasculature

SPOT Tag = aka Smart Position or Temperature Transmitting Tag, type of electronic tag, used to study movement, which transmits data via satellite

Spyhopping = a shark raising a portion of its face out of the water, in order to clear the eye/s from the surface to inspect objects

Squalidae = family of sharks, order "Squaliformes" (aka Dogfish sharks)

Squaliformes = order of sharks (families "Squalidae", "Echinorhinidae"),

Squalomorphs = superorder, squalomorph sharks (Orders 1. Hexanchiformes, 2. Squaliformes, 3.    Pristiophoriformes) (As opposed to "Galeomorphs")

Squatinidae = family of sharks, order "Squatiniformes" (aka Angel sharks)

Squatiniformes = order of sharks (family "Squatinidae")

Squatinomorphii = superorder, squatinomorphs (Orders 1. Squatinomorphes)

Stable isotope analysis (SIA) = scientific method using stable isotopes of carbon, nitrogen and sulphur accumulated in shark tissues, to determine what they have eaten in the past and where they source prey, used to determine "Trophic level"

Static lift = upwards force generated by buoyancy of a sharks' body (As opposed to "Dynamic lift)

Statoconia = "Otoliths" of sharks, which differ to that of bony fish as they do not lay down concentric annual growth rings 

Stegostomatidae = family of sharks, order "Orectolobiformes" (aka zebra shark)

Stenohaline = only able to survive  a narrow salinity range (As opposed to "Euryhaline"), common in "Elasmobranchs" 

Stomach contents analysis = scientific study of the feeding habits of fish and other animals based upon analysis of stomach contents

Sub-adult = an animal which has advanced beyond the "Juvenile" stage and is close to, but has yet to reach sexual maturity 

Sublittoral Zone = the region of the ocean below the low tide mark, where light can still reach the ocean floor. Deeper section of the "Epipelagic Zone compared to the "Intertidal Zone" (See also "Neritic Province")

Substrate = the earthy material at the bottom of a marine habitat, like dirt, rocks, sand, or gravel

Subterminal mouth = common morphology in sharks, where mouth is on the underside of the head (As opposed to "Terminal mouth")

Swim bladder = organ in bony fishes (not found in sharks), which provides "Neutral buoyancy"


Tail slapping = an "agonistic behaviour" consisting of whip-like lashing of the tail at/near the surface, hitting or directing splashes towards a competitor, known in white sharks and sandtiger sharks 

Targeted fishing = commercial fisheries utilising specially designed gear (e.g. "Gill net", "Long-lining", "Purse seine", "Trawling") to catch a specific commercially valuable species (As opposed to "Catch-all fishing"

Term size = length at birth

Terminal mouth = morphology found only in frilled, angel, whale and megamouth sharks, where mouth is situated on the tip of the snout (As opposed to "Subterminal mouths")

Tesserae = highly mineralised plate-like tiles, coating the surface of "tessellated cartilage" in the "Chondrichthyan" skeleton

Tessellated cartilage = highly mineralised cartilage found in the vertebral column and jaw of "Chondrichthyans"

Thermal niche expansion hypothesis = the theory that "Endothermic" sharks, like great whites, are more broadly distributed than "Endotherms", thanks to their wide "Thermal tolerance"

Thermal tolerance = temperature range in which an animal can survive without suffering heat or cold shock, and subsequent cellular damage

Threat display = a behaviour / sequence of behaviours which communicates a warning - often reminding the recipient of the signaller’s ability to inflict harm, with the goal to force the competitor to flee without resorting to a physical fight 

Threatened categories = term used to describe the three "IUCN" "Red List" categories ("Vulnerable", "Endangered", "Critically Endangered"which flag that a species is at risk of extinction in the wild

Thunniform swimming = most efficient form of swimming used by extremely fast species, where propulsion comes by only moving the tail, not the body (Opposed to "Anguilliform" and "Carangiform swimming")

TMAO (Trimethyl Amine Oxide) = an organic compound which is a by-product of protein metabolism. Actively retained in the body of sharks (along with "Urea") to raise the internal osmolality to be equal to that of surrounding seawater for "Osmoregulation"  

Tonic Immobility = a state of paralysis which can be induced by flipping a shark on its back or overloading the electromagnetic sense (See also "Ampullae of Lorenzini")

Torpedinidae = family of "Batoids", order "Torpediniformes" (aka torpedo electric rays)

Torpediniformes = order of "Batoids" (families "Hypnidae", "Narcinidae", Torpedinidae)

Total length (TL) = standard measure used to describe the size of sharks, measured from the tip of the "Rostrum" in a straight line to the tip of the upper "Caudal fin"

Trawling = commercial fishing method whereby a net is dragged behind a moving vessel, either at the surface, mid-water or at the bottom (Not to be confused with "Dredging")

Triakidae = family of sharks, order "Carchariniformes" (aka smoothhounds)

Tribasic cartilage support = where "pectoral fins" are made up from three types of cartilage (named proterygium, mesopterygium and metapterygium) which offers support, yet flexibility 

Trophic cascade = an ecological phenomenon triggered by the addition/removal of a species into the food chain, which results in dramatic changes to the entire ecosystem structure 

Trophic level = organisms within an ecosystem which occupy the same level in a food chain (See "Primary producer", "Heterotroph", "Mesopredator", "Apex predator")

Trophy fishing = recreational activity akin to big game hunting on land, whereby fishers catch marine species (often sharks, marlin and swordfish) for sport

Tropotaxis = orientation by simultaneous comparison of olfactory stimuli from paired receptors (See "Klinotaxis").

Trygonorrhinidae = family of "Batoids", order "Rhinopristiformes" (aka banjo rays)


Umbrella species concept = conservation biology methodo that focuses on protecting a particular species that will incidentally ensure the protection of many other co-occuring species by default

UNESCO World Heritage Site = an area or site with outstanding value to humanity, which is protected and maintained for future generations to enjoy

Upwelling = the process of seawater rising from depth to replace surface waters with cooler, more productive (aka nutrient-rich) water

Urea = an organic compound which is a by-product of protein metabolism. Actively retained in the body of sharks (along with "TMAO") to raise the internal osmolality to be equal to that of surrounding seawater for "Osmoregulation"

Urolophidae = family of "Batoids", order "Myliobatiformes" (aka round stingrays)

Urotrygonidae = family of "Batoids", order "Myliobatiformes" (aka American round stingrays) 


Vagility = ability of offspring to disperse away from their birth site

Ventral = referring to the underside of an animal (As opposed to "Dorsal")

Vertebral band analysis = method used to estimate the age of a shark by counting the annual/biannual deposition of a new band of cartilage over the skeleton

Vesicles of Savi = tactile receptors that sense vibrations, used for prey detection by some "Batoids"

Vitellogenesis = the accumulation of milk into egg yolk, as an energy storage for developing embryos

Viviparous / Viviparity = reproduction birthing live young (As opposed to "Oviparity" and "Ovoviviparity")

Vulnerable = third highest "IUCN" "Red List" "threatened category", used to flag that a species is facing extinction in the wild (See also "Not Evaluated", "Data Deficient",  "Least Concern", "Near Threatened""Endangered", Critically Endangered")


White muscle = fast-twitch muscles which generate rapid bursts of speeds in sharks (As opposed to "Red muscle")

Wobbegong = common name for a group of "Orectolobiform" sharks, characterised by ray-like flattened bodies and impressive camouflaging 


Yaw = direction of movement from left to right on a horizontal plane (See also "pitch" and "roll")

Yolk-sac viviparity = See "Ovoviviparity"

Young-of-the-Year (YOY) = juvenile animals born within the last year


Zanobatidae = family of "Batoids" (aka panrays), thought to be in the order "Rhinopristiformes", but this is disputed

Zooplankton = mixture of many different types of "Plankton" animals, ranging from microscopic (mainly diatoms, protozoans, small crustaceans, and the eggs and larval stages of larger animals) up to large animals like jellyfish. Vital food source for many marine animals at low "Trophic levels" (See also "Phytoplankton")

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