Pufferfish, Blowfish and Porcupinefish

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inflated pufferfish

Tetraodontidae is a family of primarily marine and estuarine fish that includes fish variously called pufferfish, puffers, blowfish, balloonfish, globefish, toadfish and sea squab. They are morphologically similar to the closely related porcupinefish (Diodontidae), which have large external spines. By contrast pufferfish have thinner, hidden spines which are only visible when the fish have puffed up.

There are 193 recognized species of puffer fish in 28 genera. Pufferfish, blowfish, boxfish, balloonfish and cowfish (a close relative of the box fish whose frame extends forward to give it an appearance of having horns) propels themselves using their dorsal fin and anal fin and steer using their pectoral fins and tail. For many fish it is the other way around. Box fish can move quite quickly: six body lengths a second, stabilized by the keel-like edges of its carapace.

Pufferfish, blowfish and balloonfish have two very effective methods of defense: their bodies are covered by prickly spines and they can inflate themselves to three times their real size. Their relatives include the mola mola and the boxfish. The boxfish is an unusual creature that has two sets of skeletons: one to support its body and another to support its internal organs. Resembling a pufferfish, it has a boxy shape produced by a rectangular (sometimes five sided) bony armor that covers two thirds soft their body. Its shape doesn’t look very hydrodynamic but actually is, and is especially well adapted for moving up and down and backward in the water column as well as forward. Automobile engineers at Mercedes Benz are studying the box shape to produce more aerodynamic vehicles.

Fugu, made with puffer fish, is a well-known delicacy served across Japan that a potentially-fatal toxin.. The most prized and poisonous type of fugu is torafugu, or tiger puffer fish. In Japan's Haedomari Market, the fish is auctioned off using secret bids. The tetrodotoxin found in fugu is more toxic than cyanide. People can be poisoned and died from poorly prepared fish. The Japanese government places strict regulations on who can prepare fugu. Chefs go through extensive training and are licensed. [Source: Alexandra Appolonia, Business Insider, November 3, 2022]

Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Woods Hole Oceanographic Institute whoi.edu ; Cousteau Society cousteau.org ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures

How Blowfish Inflate Themselves

deflated guinea fowl pufferfish (Arothron meleagris)

Blowfish gulp down water or air to inflate themselves like rigid balls and raise their spines to make themselves look threatening and unappetizing to predators. When bitten or swallowed by a predator they can still inflate themselves to two or three times their normal size and predators can not swallow or digest hem and have to spit them out.

Blowfish inflate themselves by pumping water or air into their stomachs (digestive functions are performed almost entirely by the small intestine).The blowfish stomach is pleated and can increase to 10 times its normal size. As the fish expands its spine bends into an upside-down position, with its internal organs squeezed between the backbone and the expanding stomach. The elastic skin stretches while a pleated inner skins hardens, giving the fish its rigidity. The pointed spikes which inwards when the fish is relaxed become erect and outward-pointing when the skin is stretched.

According to Animal Diversity Web: Balloonfish expand by swallowing mouthfuls of air or water when attacked by a predator. The balloonfish swallows air, when attacked by birds and water, when attacked by ocean predators. After ingestion through the mouth, the air or water reaches the highly elastic stomach, which has been described as a "large dilatable sac with robust esophageal and pyloric sphincters". The stomach, which has lost its digestive function, plays a key role in the inflation process. In Diodontidae (porcupinefish), the stomach is a simple sac, whereas in Tetraodontidae (pufferfish) the stomach is divided into two parts by a pyloric sphincter. As the stomach expands, it pushes the peritoneal lining into the ample peritoneal space. The peritoneal cavity expands towards the head to the mandible and towards the tail to enclose the unpaired fins. [Source: Jessica Kenzie, Animal Diversity Web (ADW) /=] /=\

Blow Fish Poison

inflated guinea fowl pufferfish (Arothron meleagris)

Tetrodotoxin is the poison in fugu. A neurotoxin that shuts down electrical signals in the nerves by disrupting the flow of sodium ions into nerve cells, it is about 500 to 1,000 times stronger than potassium cyanide. It is generally found in the intestines, liver and ovaries of the fish. One gram of fugu poison is enough to kill 500 people. There is no known antidote.

Fugu poisoning first causes dizziness, numbness of the mouth and lips, weakness, nausea, diarrhea, sweating, breathing trouble, cramps, blue lips, intense itchiness, vomiting, and dilated pupils. Victims who eat a lot go into a zombie sleep in which victims are aware of what is going on but can't move.

Powerful toxins (lethal dose): 1) anthrax (0.0002); 2) cone shell (0.004); 3) textrodoxotine in the blue ring octopus and puffer fish (0.008); 4) inland taipan snake (0.025); 5) eastern brown snake (0.036); 6) Dubois’s sea snake (0.044); 7) coastal taipan snake (0.105); 8) beaked sea snake (0.113); 9) western tiger snake (0.194); 10) mainland tiger snake (0.214); 11) common death adder (0.500). Lethal doses is defined as the amount in milligrams needed to kill 50 percent of the animals tested.

Some fugu are poisonous and some aren’t, but even experts can’t explain why. Some scientists believe fugu is not naturally toxic. They have argued that fugu get the poison from ingesting tetrodotoxin-laden vibrio bacteria that is found in creatures that puffer fish such as starfish, worms and shellfish Others disagree, saying a fugu’s toxicity is produced by poison glands beneath the ski

Pufferfish Creates Mysterious Circles on the Sea Floor When Mating

In 2013 it was discovered that 2.1-meter-(7 foot)-in-diameter "mystery circles" made on on the ocean floor near Japan were made by a 12.7-centimeters (5-inch) long puffer fish. The intricatel- patterned symmetrical circles were first noticed by divers in 1995 and are made male fish trying to attract females in sort of the same way that male bowerbirds create elaborate nests to attract mates in Australia. [Source: Mindy Weisberger, Live Science, February 14, 2023]

Smooth Toadfish (Tetractenos glaber)

Live Science reported: Males swim along the seafloor flapping their fins to sculpt the remarkably intricate ridges and valleys — a process that take seven to nine days — and then decorate them with shell fragments and sediment. After interested females are fertilized, they lay their eggs in the nest site at the center.

Though the structures are beautiful, scientists wrote in 2013 that the lines and shapes carved by the pufferfish serve to channel sediment particles, and likely don't serve an aesthetic purpose. There is a chance that it’s only the fine sand the females are after, not the formations’ intricate patterns or symmetry

Hiroshi Kawase, the curator of the Coastal Branch of Natural History Museum and Institute in Chiba, Japan, told Live Science. The male first radially aligned ridges and valleys outside the nest site. Second, the male decorates these ridges with fragments of shells. Third, the male gathers fine sediments to give the resulting formation a distinctive look and coloring. He added nobody knows exactly what the females are looking for in these circles or what traits they find desirable. [Source: Live Science, October 3, 2013]

Long-Spined Porcupine Fish

Long-spined porcupine fish (Scientific name: Diodon holocanthus) are also known as blotched porcupine, balloonfish, spiny puffer and spiny balloonfish. They are distributed throughout the world in the tropics and semitropics and are native to the Indian Ocean, Atlantic Ocean and Pacific Ocean. In the U.S. they are found along the Pacific coast, the Florida Keys and Hawaii. They are also common in the Caribbean and eastern Asia. [Source: Jessica Kenzie, Animal Diversity Web (ADW) /=]

Adults are found in relatively shallow areas of the ocean. You can typically find them in coastal areas, sea grass beds, coral reefs and mangrove areas. The larvae however, are found in open ocean in the pelagic zone. They bob around in their shells for about four days before hatching. Relatives of Long-spined porcupine fish are popular in Japanese fugu restaurants. However, long-spined porcupine fish are not normally eaten. Dried, inflated one are sold as novelties to tourists though

Long-spined porcupine fish (Diodon holocanthus)

Long-spined porcupine fish are nocturnal (active at night), predatory and remain hidden during the day. According to Animal Diversity Web: Individuals have been observed resting near ledges and shallow caves of the rocky sea floor in the Gulf of California and ledges or holes in the Florida Keys in the daytime In coral reefs around Hawaii and the West Indies, Long-spined porcupine fish' main food source is pagurid crabs (hermit crabs) and prosobranch gastropods, which include familiar marine organisms such as abalones, limpets, top shells, periwinkles, boat shells, conchs, moon snails, and whelks

The teeth of both the upper and lower jaws of Long-spined porcupine fish are fused, forming a solid, heavy beak ideal for cracking the shells of snails, sea urchins and hermit crabs. Their relatively large eyes help them locate prey at night. Long-spined porcupine fish are slow swimmer. One advantage it has is the ability maneuver into tight prey-rich places using its pectoral, pelvic and anal fins. This is especially helpful in complex habitat such as coral reefs. The fish uses its tail primarily for steering and for occasional bursts of speed. /=\

Long-Spined Porcupine Fish Characteristics and Reproduction

Adult Long-spined porcupine fish range in length from about 30.5 to 61 centimeters (one to two feet). In appearance, Long-spined porcupine fish resembles its closest cousin, the spot-fin porcupinefish (D. hystrix) described above. An easy way to tell these two apart is by checking for spots on the fins: The spot-fin porcupinefish has them; the long-spined porcupine fish doesn’t. [Source: Jessica Kenzie, Animal Diversity Web (ADW) /=]

According to Animal Diversity Web (ADW) the fish has dark patches along its sides and back, but perhaps its most telling feature is the long spines that protrude from all over its body, excluding the fins and face. The spines are actually modified scales, which lay flat against its body most of the time. In some relatives of the balloonfish, a toxic chemical, tetrodotoxin, is found in the skin and spines. However, only trace amounts of tetrodotoxin have been found in balloonfish, mainly concentrated in the ovaries. They sense using touch and chemicals usually detected with smell. /=\

range of Long-spined porcupine fish (Diodon holocanthus)

Long-spined porcupine fish reproduces like other fish. During the spawning season, a male pushes a female to the surface and they immediately spawn. The round eggs float in the water. Until they are 10 days old, Long-spined porcupine fish larvae retain a thin shell covering, which is then lost. At this time, Long-spined porcupine fish begins to develop spines. The larvae metamorphosize after about three weeks . After this metamorphosis, fins and fin rays are present, the teeth are formed, and adult olive and brown coloring develops . Dark spots appear on the belly, which may help camouflage the juveniles in floating sargassum from underwater predators such as the mahi mahi . The juvenile loses this underside spotting when it reaches the adult stage. At this point in development, spine elongation and body growth occur. The larval stage of Long-spined porcupine fish is yellow with red spots and well-developed functional mouth, eyes and gas bladder. /=\

How Long-Spined Porcupine Fish Inflates Themselves

The skeletal structure of long-spined porcupine fish facilitates inflation. Because the balloonfish lacks pleural ribs and a pelvic girdle, expansion is not as strictly inhibited as in most fish. The vertebral column is also highly flexible. It bends in an arc towards the dorsal side of the fish, allowing Long-spined porcupine fish to attain its characteristic spherical shape upon inflation.

In addition to the elastic stomach, generous peritoneal space and skeletal structure, balloonfish skin is also specialized for inflation. The skin of Long-spined porcupine fish is highly elastic because of microfolds in the epidermis and collagen fibers of the dermis. These allow Long-spined porcupine fish to extend through 40 percent of its initial length before it begins to stiffen. /=\

Spot-fin porcupinefish (Diodon hystrix)

When Long-spined porcupine inflates with water or or air the dangerous spines on its body stick out. The entire body swells two to three times in diameter as the stomach expands. The process of inflation is called an "anti-predatory defense mechanism". Long-spined porcupine fish demonstrates the most pronounced spherical shape of all pufferfish when inflated. The extremely inflated body shape also helps the fish avoid "gape-limited predators".— predators that can't open their mouths very wide. In Hawaii, the only known predator of adult balloonfish is the tiger shark. /=\

Spot-Fin Porcupinefish

Spot-fin porcupinefish (Scientific name:Diodon hystrix) is also known as the spotted porcupinefish, black-spotted porcupinefish or simply porcupinefish. Their lifespan in captivity is up to years. Adults are typically found at depths of one to 50 meters (3.28 to 164 feet) in holes and crevices in inshore areas including lagoons, caves, shipwrecks, reefs, and ledges, as well as in seamount areas. They are most commonly seen between three and 20 meters. Juveniles are pelagic (living in the open ocean, far from land) until reaching 20 centimeters in length, and become benthic (living on or near the bottom of the sea) after that.[Source: Amber Baker and Ashley Koser, Animal Diversity Web (ADW) /=]

Spot-fin porcupinefish are widely distributed in the Atlantic, Pacific and Indian Oceans, ranging from eastern Africa in the west Indian Ocean, from San Diego, California to Chile in the eastern Pacific Ocean, and from Massachusetts to Brazil in western Atlantic Ocean, as well as the Gulf of Mexico, the Caribbean Mediterranean and Red Seas and off the coast of New Zealand..

Spot-fin porcupinefish are well-known for their ability to inflate their bodies by swallowing water, causing their spines to extend outwards and preventing most predators from swallowing them. They also secrete dermal toxins that are poisonous to many species. Despite this some large fish do they on them such as wahoo, dolphinfish, tiger shark, white marlin and bluefin tuna.

black-saddled toby

Spot-fin porcupinefish are intermediate links in the reef food chain, serving both as predators of benthic invertebrates and as prey for larger predators. Humans utilize them for the pet trade and food; their body parts are sources of valuable materials research and education.

The fish are sold in the home aquarium trade, eaten as fugu in Japan and their bodies are made into things like lamps and sold as souvenirs for tourists in tropical areas. Traditionally, the hardened bodies were used as war helmets, by the Gilbertese people in what is now Kiribati.

Spot-fin porcupine fish are not considered endangered or vulnerable to extinction, according to the World Conservation Union. They have not been evaluated for the International Union for Conservation of Nature (IUCN) Red List. They have no special status according to the Convention on the International Trade in Endangered Species (CITES).

Spot-Fin Porcupinefish Characteristics and Behavior

Spot-fin porcupinefish weigh up 2.8 kilograms (6.17 pounds) and range in length from 40 to 91 centimeters (15.75 to 36 inches). They are cold blooded (ectothermic, use heat from the environment and adapt their behavior to regulate body temperature), have bilateral symmetry (both sides of the animal are the same) and poisonous. There are slight differences in body shape and color between males and females.[Source: Amber Baker and Ashley Koser, Animal Diversity Web (ADW) /=]

According to Animal Diversity Web: Spot-fin porcupinefish have round, expandable, slender bodies with small fins. These fish lack pelvic fins, and the rounded dorsal and anal fins are positioned near the caudal fin. They have 22 to 25 pectoral fin rays, 14 to 17 dorsal fin rays, and 14 to 16 anal fin rays. They are covered in long spines, which lie flat along their bodies when they are not inflated, including a longitudinal row of spines (14 to 20) between their snouts and dorsal fins, as well as small spines covering their caudal peduncle area. Body color varies, but they are generally uniformly dull brown to green with the body covered in small dark spots and markings, with a pale belly that is surrounded by a dusky ring. Their fins do not have spots. These fish have large eyes and wide, flattened mouths. Their teeth are fused together and they have very strong jaws.

When spot-fin porcupinefish are threatened, they inflate their bodies by swallowing water. Their integument is very flexible, allowing expansion of the body to up to three times its original size. When no longer threatened, excess water is expelled and the fish returns to its normal size. These fish are typically solitary, outside of breeding, and are nocturnal (active at night),, hiding during daylight hours. They communicate with vision, touch and chemicals usually detected by smelling and sense using vision, touch, vibrations and chemicals usually detected with smell. As in other bony fishes, Spot-fin porcupinefish use their eyes to see, nares to sense dissolved chemicals, and a lateral line to detect vibrations and movement via changes in water pressure.

Spot-fin porcupinefish are durophagous (eat animals with hard-shells or exoskeleton) and carnivorous. They have strong jaws and teeth that are fused together, specializations for eating hard-shelled creatures. Their beaked mouths can catch and crush sea urchins, crabs, snails, and clams while their large, rubbery lips protect them from being injured by spines and broken shells. These fish commonly scavenge and search for prey in sandy areas, crevices, and caves.

Spot-Fin Porcupinefish Mating, Reproduction and Offspring

Spot-fin porcupinefish are oviparous (young are hatched from eggs) and iteroparous (offspring are produced in groups). They engage in seasonal breeding, external reproduction in which sperm from the male fertilizes the female’s egg outside her and employ broadcast (group) spawning, the main mode of reproduction in the sea. It involves the release of both eggs and sperm into the water and contact between sperm and egg and fertilization occur externally. [Source: Amber Baker and Ashley Koser, Animal Diversity Web (ADW) /=]

Spot-fin porcupinefish breed once a year. The breeding season is assumed to be May-August. The fish are polygynandrous (promiscuous), with both males and females having multiple partners. The average time to hatching is two days. There is no parental involvement in the raising of offspring. Planktonic larvae develop independently in the water column. Their life cycle is characterized by metamorphosis — a process of development in which individuals change in shape or structure as they grow. /=\

As broadcast spawner; males and females mate promiscuously during spawning events. According to Animal Diversity Web: Although mating behavior has not been observed for this species, in captivity or in the wild, it has been observed for captive Diodon holocanthus, a closely related species. Breeding begins when water temperatures reach approximately 25°C (77°F). Multiple males approach a female at a time, bringing her up to the surface of the water where, if she has ripe eggs, she will release them. All of the males (usually 4-5) contribute sperm. It is unknown how many offspring are produced by these fish at a time or what their age at sexual maturity is.

Spot-fin porcupinefish eggs are buoyant, pelagic (living in the open ocean, far from land), spherical, and 1.9-2.1 millimeters in diameter. About five days after fertilization, eggs hatch and larvae, which average 2.6 millimeters in length, float in the open ocean near the surface. Hatchlings have large amounts of yolk still attached to them. Within two days after hatching, larvae have formed fully functional mouths and their eyes have become fully pigmented. Body coloration is mainly orange and they are more highly pigmented dorsally. Larvae maintain a thin shell until they have reached about five millimeters in length (at about 10 days old). At this time they metamorphose into spiny juveniles. Within three weeks, fins, fin rays, and teeth have formed. Juvenile spot-fin porcupinefish become olive to brown in color with dark spots on their ventral sides, camouflaging them in the mats of seaweed where they hide until moving inshore, usually when they reach at least 20 centimeters in length.

Image Sources: Wikimedia Commons; YouTube, Animal Diversity Web, NOAA

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated March 2023

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