The Pondicherry shark (Carcharhinus hemiodon) is an extremely rare species of requiem shark, in the family Carcharhinidae. A small and stocky gray shark, it grows not much longer than 1 m (3.3 ft) and has a fairly long, pointed snout. This species can be identified by the shape of its upper teeth, which are strongly serrated near the base and smooth-edged near the tip, and by its first dorsal fin, which is large with a long free rear tip. Furthermore, this shark has prominent black tips on its pectoral fins, second dorsal fin, and caudal fin lower lobe.
The Pondicherry shark is critically endangered. It was once found throughout Indo-Pacific coastal waters from the Gulf of Oman to New Guinea, and is known to enter fresh water. Fewer than 20 specimens are available for study, and most aspects of its natural history are unknown. It probably feeds on bony fishes, cephalopods, and crustaceans, and gives birth to live young with the embryos forming a placental connection to their mother. While the International Union for Conservation of Nature (IUCN) has listed the Pondicherry shark as Critically endangered, it had been thought to be extinct since the 1970s. It is probably threatened by intense and escalating fishing pressure throughout its range. The shark is among the 25 "most wanted lost" species that are the focus of Global Wildlife Conservation's "Search for Lost Species" initiative. The Pondicherry has been spotted in rivers in India in the late 2010s. A Pondicherry shark was caught in the Menik Ganga (river) in SE Sri Lanka in 2011. It was photographed and released alive. (Full article...)
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Toxotes chatareus, sometimes known by the common namescommon archerfish, seven-spot archerfish or largescale archerfish, is a species of perciform fish in the archerfish genus Toxotes.
They are usually no larger than 20 centimetres (7.9 in) but may grow up to 40 centimetres (16 in). Unlike most archerfish, T. chatareus are sooty rather than silvery in colour. They are omnivorous, feeding on insects, fish, and vegetative matter at the surface of the water. Breeding occurs in the wet season, and 20,000 to 150,000 eggs may be laid at one time. (Full article...)
The oceanic whitetip shark (Carcharhinus longimanus) is a large pelagicrequiem shark inhabiting tropical and warm temperate seas. It has a stocky body with long, white-tipped, rounded fins. The species is typically solitary, though they may gather in large numbers at food concentrations. Bony fish and cephalopods are the main components of its diet and females give live birth.
Though slow-moving, the shark is opportunistic and aggressive, and is reputed to be dangerous to shipwreck survivors. The IUCN Red List considers the species to be critically endangered. Recent studies show steeply declining populations as they are harvested for their fins and meat. As with other shark species, the whitetip faces mounting fishing pressure throughout its range. (Full article...)
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The viper dogfish or viper shark (Trigonognathus kabeyai) is a rare species of dogfish shark in the familyEtmopteridae, and the only extant member of its genus. It has been found in the Pacific Ocean off southern Japan, the Bonin Islands, Pacific Ocean off northern Taitung County and the Northwestern Hawaiian Islands. This species inhabits upper continental slopes and seamounts. It may migrate vertically, shifting between bottom waters 270–360 m (890–1,180 ft) deep during the day and upper waters less than 150 m (490 ft) deep at night. A slender, black shark reaching 54 cm (21 in) in length, the viper dogfish can be recognized by its narrow, triangular jaws and well-spaced, fang-like teeth. It also has two spined dorsal fins, dermal denticles with faceted crowns, and numerous light-emitting photophores concentrated on its ventral surface.
Feeding mainly on bony fishes, the viper dogfish captures prey by protruding its jaws and impaling them with its teeth. Its impressive gape allows it to swallow relatively large fish whole. The skeletal and muscular structure of its head shows unique features that support this feeding mechanism, which is unlike that of other dogfish sharks. This shark gives birth to live young, which are nourished by yolk during gestation; the litter size is probably fewer than 26 pups. Small numbers of viper dogfish are caught incidentally in purse seines and bottom trawls. (Full article...)
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The ocellated electric ray or bullseye electric ray (Diplobatis ommata) is a species of electric ray in the familyNarcinidae, native to the shallow inshore waters of the eastern central Pacific from the Gulf of California to Ecuador. Reaching 25 cm (9.8 in) in length, this species has a rounded pectoral fin disc and pelvic fins with convex margins. Its short and thick tail bears two dorsal fins and terminates in a triangular caudal fin. The ocellated electric ray is named for the distinctive large eyespot on the middle of its disc, consisting of a black or yellow center surrounded by concentric rings. Its dorsal coloration is otherwise highly variable, ranging from plain to ornately patterned on a light to dark brown background. The front part of its disc is darker brown.
Cutthroat trout usually inhabit and spawn in small to moderately large, clear, well-oxygenated, shallow rivers with gravel bottoms. They reproduce in clear, cold, moderately deep lakes. They are native to the alluvial or freestone streams that are typical tributaries of the rivers of the Pacific Basin, Great Basin and Rocky Mountains. Cutthroat trout spawn in the spring and may inadvertently but naturally hybridize with rainbow trout, producing fertile cutbows. Some populations of the coastal cutthroat trout (O. c. clarkii) are semi-anadromous. (Full article...)
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The night shark (Carcharhinus signatus) is a species of requiem shark, in the familyCarcharhinidae, found in the temperate and tropical waters of the Atlantic Ocean. An inhabitant of the outer continental shelf and upper continental slope, this shark most commonly occurs at depths of 50–600 m (160–1,970 ft) and conducts a diel vertical migration, spending the day in deeper water and moving into shallower waters at night. Off northeastern Brazil, large numbers congregate around seamounts of varying depths. A slender, streamlined species, the night shark typically reaches a length of 2 m (6.6 ft). It can be identified by its long, pointed snout and large, green eyes (when alive), and is dark grayish blue or brown above and white below.
Night sharks are quick, nocturnally active, schoolingpredators that feed mainly on small bony fishes and squid. Reproduction is viviparous as with the other members of its family; females mate during the summer and give birth to litters of usually 12–18 pups after a gestation period of a year. This deepwater species is not known to pose a danger to humans. It is caught incidentally by commercialtuna and swordfishlongline fisheries in the western Atlantic, and also by a targeted longline fishery operating off northeastern Brazil. The night shark is highly valued for its fins, and additionally as a source of meat, liver oil, and fishmeal. However, most sharks caught off northeastern Brazil have been found to contain unsafe concentrations of mercury. (Full article...)
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Adult rainbow trout
The rainbow trout (Oncorhynchus mykiss) is a species of trout native to cold-water tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an anadromous (sea-run) form of the coastal rainbow trout(O. m. irideus) or Columbia River redband trout(O. m. gairdneri) that usually returns to freshwater to spawn after living two to three years in the ocean. Freshwater forms that have been introduced into the Great Lakes and migrate into tributaries to spawn are also called steelhead.
Adult freshwater stream rainbow trout average between 0.5 and 2.5 kilograms (1 and 5 lb), while lake-dwelling and anadromous forms may reach 9 kg (20 lb). Coloration varies widely based on subspecies, forms, and habitat. Adult fish are distinguished by a broad reddish stripe along the lateral line, from gills to the tail, which is most vivid in breeding males. (Full article...)
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Two neighboring Eigenmannia perform the jamming avoidance response: When two fish with around the same frequency meet, one fish shifts its frequency upward and the other shifts its frequency downward.
The jamming avoidance response is a behavior of some species of weakly electric fish. It occurs when two electric fish with wave discharges meet – if their discharge frequencies are very similar, each fish shifts its discharge frequency to increase the difference between the two. By doing this, both fish prevent jamming of their sense of electroreception.
The copper shark (Carcharhinus brachyurus), bronze whaler, or narrowtooth shark is a species of requiem shark found mostly in temperatelatitudes. It is distributed in a number of separate populations in the northeastern and southwestern Atlantic, off southern Africa, in the northwestern and eastern Pacific, and around Australia and New Zealand, with scattered reports from equatorial regions. The species can be found from brackish rivers and estuaries to shallow bays and harbors, to offshore waters 100 m (330 ft) deep or more. Females are found apart from males for most of the year, and conduct seasonal migrations. A large species reaching 3.3 m (11 ft) long, the copper shark is difficult to distinguish from other large requiem sharks. It is characterized by its narrow, hook-shaped upper teeth, lack of a prominent ridge between the dorsal fins, and plain bronze coloration.
Feeding mainly on cephalopods, bony fishes, and other cartilaginous fishes, the copper shark is a fast-swimming predator that has been known to hunt in large groups, using their numbers to their advantage; however for most of the time they remain solitary. Off South Africa, this species associates closely with the annual sardine run, involving millions of southern African pilchard (Sardinops sagax). Like other requiem sharks, it is viviparous, with the developing embryos mainly nourished through a placental connection formed from the depleted yolk sac. Females bear litters of 7 to 24 pups every other year in coastal nursery areas, after a gestation period of 12 or perhaps as long as 21 months. It is extremely slow-growing, with males and females not reaching maturity until 13–19 and 19–20 years of age respectively. (Full article...)
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The goblin shark (Mitsukurina owstoni) is a rare species of deep-sea shark. Sometimes called a "living fossil", it is the only extant representative of the familyMitsukurinidae, a lineage some 125 million years old. This pink-skinned animal has a distinctive profile with an elongated, flat snout, and highly protrusible jaws containing prominent nail-like teeth. It is usually between 3 and 4 m (10 and 13 ft) long when mature, though it can grow considerably larger such as one captured in 2000 that is thought to have measured 6 m (20 ft). Goblin sharks are benthopelagic creatures that inhabit upper continental slopes, submarine canyons, and seamounts throughout the world at depths greater than 100 m (330 ft), with adults found deeper than juveniles. Some researchers believe that these sharks could also dive to depths of up to 1,300 m (4,270 ft), for short periods of time.
The creek whaler (Carcharhinus fitzroyensis) is a common species of requiem shark, and part of the family Carcharhinidae, endemic to northern Australia. It frequents shallow waters close to shore, including estuaries. This small, stocky shark usually grows to 1.0–1.3 m (3.3–4.3 ft) long and is brownish in color without conspicuous fin markings. It can be identified by its long snout, large, triangular pectoral fins, and large, anteriorly positioned first dorsal fin.
The diet of the creek whaler consists mainly of small teleost fishes and crustaceans. It is viviparous, with the unborn young being sustained through a placental connection. The defined mating season lasts from May to July. Females give birth to one to seven pups annually, following a gestation period of seven to 9 months. A small number of creek whalers are caught incidentally in inshoregillnets and used for food, but the effect of fishing on its population seems to be inconsequential. As a result, the IUCN has listed this species under Least Concern. (Full article...)
The body of an alligator gar is torpedo-shaped, usually brown or olive colored, fading to a lighter gray or yellow ventral surface. In very rare occurrences, they can also be black, seen in gars that have a high level of melanin. Their scales are not like the scales of other fishes; rather, they are ganoid scales, which are bone-like, rhomboidal-shaped scales, often with serrated edges, and covered by an enamel-like substance. Ganoid scales are nearly impenetrable, and are excellent protection against predation. Unlike other gar species, the upper jaw of an alligator gar has a dual row of large, sharp teeth that are used to impale and hold prey. Alligator gar are stalking, ambush predators, primarily piscivores, but they also ambush and eat waterfowl and small mammals they find floating on the water's surface. (Full article...)
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The dwarf pufferfish (Carinotetraodon travancoricus), also known as the Malabar pufferfish, pygmy pufferfish, or pea pufferfish, is a small freshwaterpufferfishendemic to Kerala and southern Karnataka in Southwest India. They are popular in aquaria for their bright colours and small size. At a maximum total length of 3.5 cm, dwarf pufferfish are one of the smallest pufferfish in the world. They closely resemble the related Carinotetraodon imitator, and the two can be difficult to distinguish. C. imitator was not recognised as a different species until 1999.
Dwarf pufferfish dwell at the bottom of heavily vegetated waterways, predating small animals. Unlike other species of pufferfish, they are found in large groups in the wild. They breed throughout most of the year, with spawning pairs producing 1–5 eggs in 1–4 day intervals. Habitat loss and overharvesting for the aquarium trade threaten wild populations of dwarf pufferfish. (Full article...)
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The whiskery shark (Furgaleus macki) is a species of houndshark in the family Triakidae, and the only member of its genus. This common shark inhabits the Australiancontinental shelf from Western Australia to the Bass Strait, to a depth of 220 m (720 ft). It is demersal in habits and prefers rocky and vegetated habitats. Stout-bodied and almost "humpbacked" in form, the whiskery shark can be distinguished from all other members of its family by the presence of long nasal barbels. Its two moderately large dorsal fins are roughly equal in size. It is brownish gray above and lighter below, with a pattern of darker saddles and blotches in younger sharks. This species reaches 1.6 m (5.2 ft) in length.
The diet of the whiskery shark consists almost entirely of octopuses. It is viviparous; females bear litters of four to 28 pups every other year from August to October, after a gestation period of 7–9 months. This harmless shark is used for its meat, being one of the species marketed as "flake" in Australia. It is mainly caught by a Western Australian commercialgillnetfishery. Its numbers declined significantly from overfishing in the 1970s and early 1980s, leading to the introduction of new management measures in the mid-1980s. Since then, strict fishery management has kept the whiskery shark population stable or increasing, resulting in its listing as of least concern by the International Union for Conservation of Nature. (Full article...)
Manta rays are large rays belonging to the genusMobula (formerly its own genusManta). The larger species, M. birostris, reaches 7 m (23 ft) in width, while the smaller, M. alfredi, reaches 5.5 m (18 ft). Both have triangular pectoral fins, horn-shaped cephalic fins and large, forward-facing mouths. They are classified among the Myliobatiformes (stingrays and relatives) and are placed in the familyMyliobatidae (eagle rays). They have the largest brains and brain to body ratio of all fish, and can pass the mirror test.
Mantas are found in warm temperate, subtropical and tropical waters. Both species are pelagic; M. birostrismigrates across open oceans, singly or in groups, while M. alfredi tends to be resident and coastal. They are filter feeders and eat large quantities of zooplankton, which they gather with their open mouths as they swim. However, research suggests that the majority of their diet (73%) comes from mesopelagic sources. Gestation lasts over a year and mantas give birth to live pups. Mantas may visit cleaning stations for the removal of parasites. Like whales, they breach for unknown reasons. (Full article...)
Image 2Many bristlemouth species, such as the "spark anglemouth" above, are also bathypelagic ambush predators that can swallow prey larger than themselves. They are among the most abundant of all vertebrate families. (from Pelagic fish)
Image 10Lanternfish are partial residents of the ocean epipelagic zone During the day they hide in deep waters, but at night they migrate up to surface waters to feed. (from Pelagic fish)
Image 11Red snapper, are generalized reef feeders with standard jaw and mouth structures that allow them to eat almost anything, though they prefer small fish and crustaceans. (from Coral reef fish)
Image 17Young, red flabby whalefish make nightly vertical migrations into the lower mesopelagic zone to feed on copepods. When males mature into adults, they develop a massive liver and then their jaws fuse shut. They no longer eat, but continue to metabolise the energy stored in their liver. (from Pelagic fish)
Image 20The stargazer is an ambush predator which can deliver both venom and electric shocks. It has been called "the meanest thing in creation". (from Coastal fish)
Image 26World distribution of plankton (from Coastal fish)
Image 27The stoplight loosejaw is also one of the few fishes that produce red bioluminescence. As most of their prey cannot perceive red light, this allows it to hunt with an essentially invisible beam of light. (from Deep-sea fish)
Image 33Most of the rest of the mesopelagic fishes are ambush predators, such as this sabertooth fish. The sabertooth uses its telescopic, upward-pointing eyes to pick out prey silhouetted against the gloom above. Their recurved teeth prevent a captured fish from backing out. (from Pelagic fish)
Image 34The usually placid yellow tang can erect spines in its tail and slash at its opponent with rapid sideways movements (from Coral reef fish)
Image 36Most mesopelagic fishes are small filter feeders that ascend at night to feed in the nutrient rich waters of the epipelagic zone. During the day, they return to the dark, cold, oxygen-deficient waters of the mesopelagic where they are relatively safe from predators. Lanternfish account for as much as 65% of all deep sea fish biomass and are largely responsible for the deep scattering layer of the world's oceans. (from Pelagic fish)
Image 45Humans seldom encounter frilled sharks alive, so they pose little danger (though scientists have accidentally cut themselves examining their teeth). (from Deep-sea fish)
Image 46The giant whale shark, another resident of the ocean epipelagic zone, filter feeds on plankton, and periodically dives deep into the mesopelagic zone. (from Pelagic fish)
Image 47Bigeye tuna cruise the epipelagic zone at night and the mesopelagic zone during the day (from Deep-sea fish)
Image 51The stoplight loosejaw has a lower jaw one-quarter as long as its body. The jaw has no floor and is attached only by a hinge and a modified tongue bone. Large fang-like teeth in the front are followed by many small barbed teeth. (from Deep-sea fish)
Image 60The daggertooth paralyses other mesopelagic fish when it bites them with its dagger-like teeth (from Deep-sea fish)
Image 61Shortfin mako shark make long seasonal migrations. They appear to follow temperature gradients, and have been recorded travelling more than 4,500 km in one year. (from Pelagic fish)
Image 62The great hammerhead detects the electrical signatures of stingrays buried in the sand and pins them with its "hammer". (from Demersal fish)
Image 63The humpback anglerfish is a bathypelagic ambush predator, which attracts prey with a bioluminescent lure. It can ingest prey larger than itself, which it swallows with an inrush of water when it opens its mouth. (from Pelagic fish)
Image 64The rattail Coryphaenoides armatus (abyssal grenadier) on the Davidson Seamount at a depth of 2,253 metres (7,392 ft). (from Deep-sea fish)
Image 66Long-snouted lancetfish. Lancetfish are ambush predators which spend all their time in the mesopelagic zone. They are among the largest mesopelagic fishes (up to 2 m). (from Deep-sea fish)
Image 67In the foreground is an orange-lined triggerfish displaying spines. Triggerfish have mouths that crush shells. Orange-lined triggerfish are particularly aggressive. The black and white fish are three-stripe damselfish and the unstriped fish are blue-green chromis damselfish. If the triggerfish attacks, the damselfish will hide in the nearby cauliflower coral. If the triggerfish wants to hide, it will squeeze into a coral crevice and lock itself in place with its spines. (from Coral reef fish)
Image 70Demersal fish output in 2005 (from Demersal fish)
Image 71Surgeonfish are among the most common of coral reef herbivores, often feeding in shoals. This may be a mechanism for overwhelming the highly aggressive defence responses of small territorial damselfishes that vigorously guard small patches of algae on coral reefs. (from Coral reef fish)
Image 78Coral reefs support flourishing ecosystems, paradoxically in clear, low nutrient waters, along tropical continental coasts and around volcanic islands. Coral reef fish are numerous and diverse. (from Coastal fish)
Image 79Cod-like fishes, like this morid cod have a barbel (fleshy filament) on their lower jaw which they use to detect prey buried in the sand or mud. (from Coastal fish)
A sketch of a longnose sawshark (Pristiophorus cirratus), a species of sawshark found in the eastern Indian Ocean around southern Australia on the continental shelf at depths of between 40 and 310 m (130 and 1,020 ft). It is a medium-sized shark with a saw-like flattened snout which measures up to thirty percent of its body size.
People jigging—fishing with a type of lure known as a "jig"—for squid in Queenscliff, Victoria, Australia. A jig consists of a lead sinker with a hook molded into it and usually covered by a soft body to attract fish. Jigs are intended to create a jerky, vertical motion, as opposed to spinnerbaits which move through the water horizontally.
Icefish are a type of Antarctic fish belonging to various families, including the Channichthyidae family. They have no haemoglobin and their blood is transparent. They feed on krill, copepods, and other fish. Icefish rely on well-oxygenated water and absorb oxygen directly through the skin as they lack red blood cells.
The round ribbontail ray (Taeniura meyeni) is a species of stingray in the family Dasyatidae, found throughout the nearshore waters of the tropical Indo-Pacific region. Reaching 1.8 m (6 ft) across, this large ray is characterized by a thick, rounded pectoral fin disc covered by small tubercles on top, and a relatively short tail bearing a single venomous spine. The ray is well-camouflaged when lying on the seabed; it is largely nocturnal, and preys on molluscs, crustaceans and bony fish. Mature females bear litters of up to seven pups, which are fed during gestation on "uterine milk", a product secreted by the walls of the oviduct. This round ribbontail ray was photographed in Lakshadweep, India.
The Peacock flounder (Bothus mancus) is a species of lefteye flounder found widely in relatively shallow waters in the Indo-Pacific. This photomontage shows four separate views of the same fish, each several minutes apart, starting from the top left. Over the course of the photos, the fish changes its colors to match its new surroundings, and then finally (bottom right) buries itself in the sand, leaving only the eyes protruding.
The spotted trunkfish (Lactophrys bicaudalis) is a species of ray-finned fish in the family Ostraciidae, native to the Caribbean Sea and parts of the western Atlantic Ocean. Members of this family are known as boxfishes because they have a hard outer covering consisting of hexagonal, plate-like scales fused together into a solid, triangular or box-like carapace. Because of this casing, the body of the spotted trunkfish is not flexible, and locomotion is normally limited to slow movements performed by rippling its dorsal and anal fins and gently beating its pectoral fins. If faster motion is required, it can additionally use its caudal fin for propulsion. This spotted trunkfish was photographed at a depth of about 40 ft (12 m) at Bari Reef, Bonaire.
Rhinogobius flumineus, also known as the lizard goby, is a species of goby in the family Oxudercidaeendemic to Japan, seen here in Hamamatsu, Shizuoka Prefecture. A small freshwater fish found in fast-flowing streams, it maintains its position against the current by gripping a rock with a sucker formed from two of its fins. The fish's mouth is slightly asymmetric; dextral (right-sided) fish tend to curve their bodies to the right as they rest, while sinistral (left-sided) fish tend to adopt a left-curving posture. The fish are omnivorous, picking edible items off the stream bed with the side of the mouth, but dextral and sinistral fish show no preference for which side of the mouth they use for this purpose.
A plate with fossils of Pseudostacus sp. (lobster, left) and Diplomystus birdii (fish, right), from the Hakel paleontological formation in Lebanon. The paleontological sites of Lebanon contain deposits of some of the best-preserved fossils in the world, and include some species found nowhere else. The most famous of these is the Lebanese lagerstätten of the Late Cretaceous age.
The mandarinfish (Synchiropus splendidus, not to be confused with the similarly named mandarin fish) is a small (~6 cm or 2.4 in), brightly-colored member of the dragonet family, popular in the saltwater aquarium trade. The mandarinfish is native to the Western Pacific, ranging approximately from the Ryukyu Islands south to Australia.
Mudskippers, such as this Periophthalmodon septemradiatus, are uniquely adapted to a completely amphibious lifestyle. They are active when out of water, feeding and interacting with one another, as well as defending their territories.
The orbicular batfish (Platax orbicularis) is a batfish endemic to the Indian and Pacific Oceans. It has a thin, disc-shaped body, and male can grow up to 50 centimetres (20 in) in length. In the wild, the orbicular batfish lives in brackish or marine waters, usually around reefs, at depths from 5 to 30 metres (20 to 100 ft). It is also a popular aquarium fish, although captive specimens generally do not grow as long as wild ones.
Koi are ornamental domesticated varieties of the common carpCyprinus carpio, originated from China and widely spread in Japan. They are very closely related to goldfish. The word "koi" comes from Japanese meaning "carp".
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