Conger (/ˈkɒŋɡər/ KONG-gər) is a genus of marine congrid eels.[2] It includes some of the largest types of eels, ranging up to 6 m (20 ft) in length,[3] in the case of the European conger. Large congers have often been observed by divers during the day in parts of the Mediterranean Sea, and both European and American congers are sometimes caught by fishermen along the European and North American coasts. The life histories of most conger eels are poorly known. Based on collections of their small leptocephalus larvae, the American conger eel has been found to spawn in the southwestern Sargasso Sea, close to the spawning areas of the Atlantic freshwater eels. “Conger” or “conger eel” is sometimes included in the common names of species of the family Congridae, including members of this genus. Fishing for congers is recorded in the 12th-century; the Norman taxation Pipe Roll recorded two éperquerie on Guernsey and one on Sark which were designated places where conger were dried. One species of the conger eel, Conger myriaster, is an important food fish in East Asia. It is often served as sushi. Congers are predators and can attack humans. In July, 2013, a diver was attacked by a conger eel in Killary HarbourIreland, at a depth of 25 metres (82 ft). The eel bit a large chunk from his face. The diver reported the creature was more than 1.8 metres (5 ft 11 in) in length and “about the width of a human thigh”.


Moray eels, or Muraenidae (/ˈmɒr, məˈr/), are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but several species are regularly seen in brackish water, and a few are found in fresh water. The dorsal fin extends from just behind the head along the back and joins seamlessly with the caudal and anal fins. Most species lack pectoral and pelvic fins, adding to their serpentine appearance. Their eyes are rather small; morays rely mostly on their highly developed sense of smell, lying in wait to ambush prey. The body is generally patterned. In some species, the inside of the mouth is also patterned. Their jaws are wide, framing a protruding snout. Most possess large teeth used to tear flesh or grasp slippery prey items. A relatively small number of species, for example the snowflake moray (Echidna nebulosa) and zebra moray (Gymnomuraena zebra), primarily feed on crustaceans and other hard-shelled animals, and they have blunt, molar-like teeth suitable for crushing. Morays secrete a protective mucus over their smooth, scaleless skin, which in some species contains a toxin. They have much thicker skin and high densities of goblet cells in the epidermis that allows mucus to be produced at a higher rate than in other eel species. This allows sand granules to adhere to the sides of their burrows in sand-dwelling morays,[6] thus making the walls of the burrow more permanent due to the glycosylation of mucins in mucus. Their small, circular gills, located on the flanks far posterior to the mouth, require the moray to maintain a gap to facilitate respiration. The pharyngeal jaws of morays are located farther back in the head and closely resemble the oral jaws (complete with tiny “teeth”). When feeding, morays launch these jaws into the mouth cavity, where they grasp prey and transport it into the throat. Moray eels are the only known animals that use pharyngeal jaws to actively capture and restrain prey in this way. In addition to the presence of pharyngeal jaws, morays’ mouth openings extend far back into the head, compared to fishes which feed using suction. In the action of lunging at prey and biting down, water flows out the posterior side of the mouth opening, reducing waves in front of the eel which would otherwise displace prey. Thus, aggressive predation is still possible even with reduced bite times.[10] In at least one species, the California moray (Gymnothorax mordax), teeth in the roof of the mouth are able to fold down as prey slides backwards, thus preventing the teeth from breaking and maintaining a hold on prey as it is transported to the throat. Differing shapes of the jaw and teeth reflect the respective diets of different species of moray eel. Evolving separately multiple times across the Muraenidae, short, rounded jaws and molar-like teeth allow durophagous eels (e.g. Gymnomuraena zebra and genus Echidna) to consume crustaceans, while other piscivorous genera of Muraenidae have pointed jaws and longer teeth. These morphological patterns carry over to teeth positioned on the pharyngeal jaw. The moray eel can be found in both freshwater habitats and saltwater habitats. The vast majority of species are strictly marine, never entering freshwater. Of the few species known to live in freshwater, the most well-known is Gymnothorax polyuranodon. An image of Echidna nebulosa occupying a live coral reef, located in Sabang, Philippines. Within the marine realm, morays are found in shallow water nearshore areascontinental slopescontinental shelvesdeep benthic habitats, and mesopelagic zones of the ocean, and in both tropical and temperate environments.[20] Tropical oceans are typically located near the equator, whereas temperate oceans are typically located away from the equator. Most species are found in tropical or subtropical environments, with only a few species (e.g., Gymnothorax mordax and Gymnothorax prasinus) are found in temperate ocean environments. Although the moray eel can occupy both tropical oceans and temperate oceans, as well as both freshwater and saltwater, the majority of moray eels occupy warm saltwater environments, which contain reefs.[21] Within the tropical oceans and temperate oceans, the moray eel occupies shelters, such as dead patch reefs and coral rubble rocks, and less frequently occupies live coral reefs.


Snipe eels are a family, Nemichthyidae, of eels that consists of nine species in three genera. They are pelagic fishes, found in every ocean, mostly at depths of 300–600 m but sometimes as deep as 4000 m. Depending on the species, adults may reach 1–2 m (39–79 in) in length, yet they weigh only 80-400 g (a few ounces to a pound). They are distinguished by their very slender jaws that separate toward the tips as the upper jaw curves upward. The jaws appear similar to the beak of the bird called the snipe. Snipe eels are oviparous, and the juveniles, called Leptocephali (meaning small head), do not resemble the adults but have oval, leaf-shaped and transparent bodies. Different species of snipe eel have different shapes, sizes and colors. The similarly named bobtail snipe eel is actually in a different family and represented by two species, the black Cyema atrum and the bright red Neocyema erythrosoma. Snipe eels have the long, slender body typical of eels. They are distinguished by their very slender jaws that separate toward the tips as the upper jaw curves upward and which appear similar to the beak of the bird called the snipe. The vent may be near the throat (as in N. scolopaceus) or further back on the body (as in A. gilli and A. infans). Depending on the species, adults may reach 30-60 inches long, and weigh only a few ounces to a pound. The dorsal fins show wide variation, too. For example, A. gilli has fewer than 280 rays in its dorsal fin, while A. infans has more than 320. The only food items actually found in the stomachs of snipe eels have been shrimp-like crustaceans, though ichthyologists believe they should be capable of catching and eating small fish and cephalopods also. Since predatory fish often feed on eel larvae, it is presumed by scientists and ichthyologists that they feed on snipe eel larvae as well. It is also thought that larger fish eat adult snipe eels though there is not much direct evidence for this. Scientists have reported a few stories of rockfish vomiting up a snipe eel after being caught and hauled to the surface in a trawl net. Snipe eels are found in every ocean and generally occupy depths of 300–600 m, though specimens have been caught nearer the surface at night, and storms occasionally result in individuals being stranded on the shore.[20] Larval snipe eels occupy more shallow regions of 60–70 m before descending to metamorphose into adult form. Based on studies of several species of snipe eel in the Sargasso Sea and off the coast of California, it seems that snipe eels spawn mainly in the spring, but also into early summer. The juvenile forms of eels are generally called leptocephali (meaning “small head”) and do not look like their adult forms. They are flat and transparent, taking forms that may be elongated or closer to the shape of a leaf. They remain in the larval form and near the surface (upper 200 m) for several months before descending to metamorphose. This is similar to other eel species but much longer than most other fish. The bobtail snipe eels are two species of deep-sea fishes in the family Cyematidae, one only in each of two genera. They are small elongate fishes, growing up to 16 centimeters (6.3 inches) long. They are bathypelagic (deep-water ocean-dwellers) and have been found down to 5,000 meters (16,000 feet). They are found in all oceans. Cyema atrum is black, while Neocyema erythrosoma is bright red. Sawtooth eels are a family, Serrivomeridae, of eels found in temperate and tropical seas worldwide. Sawtooth eels get their name from the saw-like arrangement of inward-slanting teeth attached to the vomer bone in the roof of the mouth.[22] They are deep water pelagic fish.


The firefly squid (Watasenia scintillans), also known as the sparkling enope squid,[3] is a species of squid in the family Enoploteuthidae. It is the sole species in the monotypic genus Watasenia. The firefly squid is found in the Western Pacific Ocean at depths of 183 to 366 metres (600–1200 feet) and is bioluminescent. The mantle, head, arms and tentacles are dotted with tiny, light-producing organs called photophores. However, light is also produced from many other small organs that are scattered around the body. The luminescence is due to an ATP-dependent reaction. The squid spends the day at depths of several hundred metres, returning to the surface when night falls. It uses its abilities to sense and to produce light for counter-illumination camouflage: it matches the brightness and colour of its underside to the light coming from the surface, making it difficult for predators to detect it from below. This squid has three visual pigments located in different parts of the retina which likely allows color discrimination, each having distinct spectral sensitivities. The firefly squid measures about 3 inches (7.6 cm) long at maturity and dies after one year of life. It has the standard eight arms and two tentacles, with one pair each having three, bright light-emitting organs at the tips. The firefly squid can also light up its whole body to attract a mate. Once the squid’s eggs have been fertilized and laid, it dies, having reached the end of its one-year lifespan. Spawning, which involves large aggregations of the squid, takes place between February and July. This squid is commercially fished in Japan, accounting for an annual catch of 4,804 to 6,822 tons from 1990 to 1999.


The Saccopharyngidae are a derived lineage of unusual eels within the order Anguilliformes, and includes families Cyematidae, Monognathidae, Eurypharyngidae, Saccopharyngidae, and the proposed family Neocyematidae.[1] Most of the fish in this group are deep-dwelling and rarely seen, typically known from only a handful of specimens. Species include recognizable fish such as pelican eelsbobtail eels, and gulper eels. Some can live deep in the ocean, well into the aphotic zone, from approximately 500-1800 meters deep. Extensive research has not been conducted on them due to being indirectly observed, with some species known only from their larvae.[1] All families except for the exceptionally rare individuals of proposed family Neoceymatidae (known only from the Atlantic Ocean) are found in all major oceans. They have multiple internal differences from the rest of Anguilliformes. Notably, they have no symplectic boneoperclular bones, ribs, or swim bladders. Like many other eels, they lack scales and pelvic fins. Their myomeres (muscle segments) are V-shaped instead of W-shaped as in all other fishes, and their lateral lines have no pores, instead being modified to groups of elevated tubules. The jaws are quite large, lined with small teeth, and several types are notable for being able to consume fish larger than themselves. Some species in families Eurypharyngidae and Saccopharyngidae are bioluminescent. Like other eels, saccopharyngids have leptocephalus larvae. However, these larvae also have a number of unusual characteristics, such as remarkably deep bodies in the Cyematidae, long lower jaws in the Eurypharyngidae, and unique pigmented swellings at the ends of the gut in Saccopharyngidae and Eurypharyngidae. Until recently, the order “Saccopharyngiformes” was accepted as a separate order from Anguilliformes, based on their distinct morphological differences from the rest of the “true eels”. Genetic work over the past few years has shown that it is instead a derived lineage within the Anguilliformes.


They can be identified by their yellowish skin and characteristic blue and black rings that change color dramatically when the animal is threatened. They eat small crustaceans, including crabshermit crabsshrimp, and other small animals. They are recognized as one of the world’s most venomous marine animals. The blue-ringed octopus diet typically consists of small crabs and shrimp. They also tend to take advantage of small injured fish if they can catch them. The blue-ringed octopus pounces on its prey, seizing it with its arms and pulling it towards its mouth. It uses its horny beak to pierce through the tough crab or shrimp exoskeleton, releasing its venom. The venom paralyzes the muscles required for movement, which effectively kills the prey. The mating ritual for the blue-ringed octopus begins when a male approaches a female and begins to caress her with his modified arm, the hectocotylus. A male mates with a female by grabbing her, which sometimes completely obscures the female’s vision then they touch each other sferring sperm packets by inserting his hectocotylus into her mantle cavity repeatedly. Mating continues until the female has had enough, and in at least one species the female has to remove the over-enthusiastic male by force. Males will attempt copulation with members of their own species regardless of sex or size, but interactions between males are most often shorter in duration and end with the mounting octopus withdrawing the hectocotylus without packet insertion or struggle. The blue-ringed octopus, despite its small size, carries enough venom to kill 26 adult humans within minutes. Their bites are tiny and often painless, with many victims not realizing they have been envenomated until respiratory depression and paralysis start to set in. The octopus produces venom containing tetrodotoxinhistaminetryptamineoctopaminetaurineacetylcholine and dopamine. The venom can result in nausearespiratory arrestheart failure, severe and sometimes total paralysisblindness, and can lead to death within minutes if not treated. Death is usually from suffocation due to paralysis of the diaphragm. The major neurotoxin component of the blue-ringed octopus is a compound that was originally known as maculotoxin but was later found to be identical to tetrodotoxin, a neurotoxin also found in pufferfish, and in some poison dart frogs. Tetrodotoxin causes severe and often total body paralysis. Tetrodotoxin envenomation can result in victims being fully aware of their surroundings but unable to move. Because of the paralysis that occurs, they have no way of signaling for help or any way of indicating distress. The victim remains conscious and alert in a manner similar to curare or pancuronium bromide. This effect is temporary and will fade over a period of hours as the tetrodotoxin is metabolized and excreted by the body. In the James Bond film Octopussy, the blue-ringed octopus is the prominent symbol of the secret order of female bandits and smugglers, appearing in an aquarium tank, on silk robes, and as a tattoo on women in the order. The animal was also featured in the book State of Fear by Michael Crichton, where a terrorist organization utilized the animal’s venom as a favored murder weapon. The Adventure Zone featured a blue-ringed octopus in its “Petals To The Metal” series. A video, originally posted on TikTok, of a tourist in Australia handling a blue-ringed octopus went viral in February 2019.


The mimic octopus (Thaumoctopus mimicus) is an Indo-Pacific species of octopus capable of impersonating other local species. They are notable for being able to change their skin color and texture in order to blend in with their environment, such as algae-encrusted rock and nearby coral through pigment sacs known as chromatophores. The mimic octopus possesses chromatophores as well as the unique behavior of taking shape of various objects and animals. The species was thought to only inhabit the western and central Indo-Pacific (with most documented records from Indonesia) until one was spotted near the Great Barrier Reef on a shallow sand flat off Lizard Island in June 2012. The mimic octopus was first discovered off the coast of Sulawesi, Indonesia in 1998 on the bottom of a muddy river mouth. The mimic octopus is a smaller octopus, growing to a total length of about 60 cm (2 ft), including arms, with a diameter approximately that of a pencil at their widest. Small horns protrude from each eye. The octopus’ natural color is light brown/beige, but it usually takes on a more noticeable hue of striped white and brown to scare off predators by imitating poisonous species and vicious, territorial sea creatures. Its ability to change shape is the reason it was named the “mimic” octopus, which is its main defense besides camouflage. The mimic octopus uses a jet of water through its funnel to glide over the sand while searching for prey, typically small fish, crabs, and worms, protected by its apparently Batesian mimicry of aposematic animals. It also uses aggressive mimicry to approach wary prey, for example mimicking a crab as an apparent mate, only to devour its deceived suitor. It prefers river mouths and estuaries, as opposed to reefs which are usually preferred as shelter by other types of octopus. As it is able to impersonate poisonous fish, it is at less risk of predation than others in the open. The mimic octopus of tropical Indo-Pacific are reputed to mimic up to 15 species of other local marine organisms. Mimicry of a local, abundant flounder was observed; nearly 500 episodes were analyzed. Both octopus species mimicked the shape, swimming actions, speed, duration, and sometimes the coloration of swimming flounders. During flounder mimicry, octopuses were actively moving and conspicuous, whereas immediately before and afterwards they were camouflaged and motionless (sitting or very slowly crawling). Furthermore, when motionless, the octopuses assumed body patterns and postures that resembled small sponges, tube-worm tubes, or colonial tunicates, which were among the few objects in the open sand habitat. The key finding was that octopuses used flounder mimicry only when their movement would give away camouflage in this open habitat. In all cases, octopuses used mimicry as a primary defense. The mimic octopus can either be classified as a hunter or a forager. It is believed to be a hunter because scientists have observed and recorded the octopus having the ability to stalk prey and hunt down small fish and catch them. More often, however, the Mimic Octopus can be seen foraging for food. It does this by using a jet of water through its siphon to glide over the sand while searching for prey, and using its slender tentacles to reach into crevices in coral, as well as holes in the sand, and use its suction cups to grab small crustaceans and eat them. Because the Mimic Octopus prefers to live in shallow, murky waters, it is believed that its diet consists almost exclusively of small fish and crustaceans. The mimic octopus is native to the Indo-Pacific, ranging from the Red Sea in the west to New Caledonia in the east, and Gulf of Thailand and the Philippines in the north to the Great Barrier Reef in south. Most documented records are from Indonesia. It is primarily found in areas with sand or silt at depths of less than 15 m (49 ft). It prefers obscuring murky and muddy sea floors to blend in with its natural brown-beige coloring.


Blanket octopus is a genus of pelagic cephalopods, containing four species that occupy surface to mid-waters in subtropical and tropical oceans.[2] They are commonly known as blanket octopodes, in reference to the long, transparent webs that connect the dorsal and dorsolateral arms of the adult females. The other arms are much shorter and lack webbing. Tremoctopus violaceus exhibits the most extreme degree of sexual size-dimorphism known in any non-microscopic animal.[3][4] Females may reach 2 m (6.6 ft) in length, whereas the males are 2.4 cm. The weight ratio is at least 10,000:1, and can probably reach as much as 40,000:1. The males have a large arm in a spherical pouch modified for mating, known as a hectocotylus. During mating, this arm is detached, and kept by the female in her mantle cavity until used for fertilisation. The male almost certainly dies shortly after mating.[5] The females carry more than 100,000 eggs attached to a sausage-shaped calcareous secretion held at the base of the dorsal arms and carried by the female until hatching. Blanket octopodes are immune to the venomous Portuguese man o’ war, whose tentacles the male and immature females rip off and use for offensive and defensive purposes.[7] Like many other octopodes, the blanket octopus uses ink to intimidate potential predators.[8] Also, when threatened, the female unfurls her large net-like membranes that spread out and billow in the water, greatly increasing her apparent size.


The flapjack octopus usually appears as transparent to dark red.[4] Their maximum size is 20 centimetres (7.9 in) mantle length.[4] They have eight jointed legs which are affixed together in an umbrella shape.[5] They have a gelatinous body, which spreads into a parachute shape when maneuvering through dimly lit water.[5] The flapjack preys on small fishes and planktonic crustaceans.[4] They swim by moving their fins, pulsing their webbed arms, pushing water through their funnel for jet propulsion, or all three at once.[6] Their depth range is: Para-larvae 200 metres (660 ft), adults 500–1,500 metres (1,600–4,900 ft). This species has been reported off Eureka Bar, California, at 350 metres (1,150 ft). It is also known from Japan, off Kashima-Nada, at 530–560 metres (1,740–1,840 ft).[7] Nesis (1982/87) reports it from the Bering Sea to the Sea of Okhotsk to off central Honshū. The Opisthoteuthis californiana is one of 14 species in the genus Opisthoteuthis. These species are also collectively known as the flapjack devilfishes. Species of Opisthoteuthis are the most compressed, in the anterior-posterior axis, of any cephalopod. This flattened appearance gives them the common name of flapjack or pancake devilfish. Species are thought to be primarily benthic although they are capable of swimming and in some species the swimming may be an important component of their pouncing on minute prey. As in other cirrates, most species are poorly known.


Amphioctopus marginatus, also known as the coconut octopus and veined octopus, is a medium-sized cephalopod belonging to the genus Amphioctopus. It is found in tropical waters of the western Pacific Ocean. It commonly preys upon shrimpcrabs, and clams, and displays unusual behavior including bipedal walking and tool use (gathering coconut shells and seashells and using these for shelter). The main body of the octopus is normally 8 centimeters (3 in) long and including the arms, approximately 15 centimeters (6 in) long. The octopus displays a typical color pattern with dark ramified lines similar to veins, usually with a yellow siphon. The arms are usually dark in color, with contrasting white suckers. In many color displays, a lighter trapezoidal area can be seen immediately below the eye. The coconut octopus is found on sandy bottoms in bays or lagoons. It frequently buries itself in the sand with only its eyes uncovered. In March 2005, researchers at the University of California, Berkeley, published an article in Science in which A. marginatus was reported to show bipedal locomotion. It is one of only two octopus species known to display such behavior, the other species being Abdopus aculeatus. The authors discovered this behavior in an area off SulawesiIndonesia, where the sandy bottom was littered with coconut shells.[1] The bipedal motion appears to mimic a floating coconut. Researchers from the Melbourne Museum in Australia claimed the coconut octopus uses tools for concealment and defense by gathering available debris to create a defensive fortress. This behavior was observed in individuals in Bali and North Sulawesi in Indonesia.[3][4][5] The researchers filmed the octopus collecting coconut half-shells discarded by humans from the sea floor. They were then carried up to 20 meters (66 ft) and arranged around the body of the octopus to form a spherical hiding place similar to a clam-shell.