Pufferfish is a family of predominantly marine and estuarine fish of the Tetraodontiformes order.
The family includes several known species, variously known as bufferfish, balloonfish, blowfish, whalefish, globefish, swellfish, toadfish, toadfish, honey toads, sugar toads and sea squat.
They are morphologically similar to closely related porcupinefish, which have large outer spines (unlike the smaller, concealed spines of the Pufferfish, which are only apparent when the fish are puffed up).
The scientific name directs to the four large teeth, fused into the upper and lower plates, which are used for crushing the hard shells of crustaceans and molluscs, their natural prey.
Scientific Classification
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Tetraodontiformes
- Suborder: Tetraodontoidei
- Family: Tetraodontidae
Biologists think Pufferfish, also known as Bufferfish, have established their famous “inflatability” because their sluggish, somewhat awkward swimming style makes them vulnerable to predators.
Instead of escape, Pufferfish use their extremely elastic stomachs and the ability to easily absorb vast quantities of water (and even air if necessary) to shape themselves into an almost inedible ball many times their usual size. Some animals also have spines on their skin to make them even more palatable.
The significant amount of pufferfish species are toxic, and some are among the most poisonous vertebrates in the world.
In some species, the internal organs, such as the liver and often the skin, contain tetrodotoxins and are highly poisonous to most animals when eaten; however, the meat of some species is considered to be a delicacy in Japan (as acetate, pronounced fugu), Korea (as acetate, bok, or acetate, bogeo) and China (as acetate, hetún) when cooked by specially trained chefs who know which part is safe to eat and what part is safe to eat.
Other pufferfish species with non-toxic skin, such as the northern buffer, Sphoeroides maculatus, Chesapeake Bay, are considered to be delicacy elsewhere.
The species Torquigener albomaculosus was referred to by David Attenborough as “the greatest artist of the animal kingdom” because of the males’ unusual habit of wooing females by building sand nests consisting of complex geometric designs.
Description
They are typically small to medium in height, although a few species may be larger than 100 cm (39 in) in length.
Natural Defence
The special and distinctive natural defences of the buffer help compensate for its sluggish locomotion. It travels by integrating pectoral, dorsal, anal and caudal fin movements.
This makes it highly manoeuvrable, but very sluggish, making it a relatively easy predation target. Its tail fin is primarily used as a rudder, but it can be used for a sudden evasive burst of speed that displays none of the care and precision of its normal movements.
The excellent sight of the buffer, combined with this speed of bursting, is the first and most important protection against predators.
The secondary defence mechanism of the Pufferfish, used if successfully pursued, is to fill its extremely elastic stomach with water (or air outside the water) until it is larger and spherical in shape.
Even if they are not visible when the puffer is not inflated, all Pufferfish have pointed spines, so that a hungry predator may suddenly find himself facing an unpalatable, pointed ball rather than a slow, tasty fish.
Predators who fail to heed this warning (or are “lucky” enough to catch a buffer unexpectedly, before or during inflation) may die from shock, and predators who manage to swallow a buffer may find their stomachs full of tetrodotoxin (TTX), making buffers an unpleasant, probably lethal, choice of prey.
This neurotoxin is present predominantly in the ovaries and liver, although there are smaller concentrations in the intestines and skin, as well as trace amounts in the muscles. It does not often have a fatal impact on large animals, such as sharks, but it does kill people.
Larval Pufferfish are chemically covered by the presence of TTX on the surface of the skin, which allows predators to spit them out.
Not all Pufferfish are inherently poisonous; the flesh of the northern buffer is not toxic (a level of poison can be contained in its viscera) and is considered a delicacy in North America.
Takifugu oblongus, for example, is a fugu buffer that is not poisonous, and the level of toxin varies widely even in fish.
Neurotoxins in buffers are not generally as harmful to other organisms as they are to humans, and buffers are typically consumed by certain types of fish, such as lizardfish and sharks.
Pufferfish can shift their eyes independently, and many species can alter the colour or strength of their patterns in response to environmental changes. They are very similar in these respects to the terrestrial chameleon.
While most pufferfishes are drab, many have bright colours and distinctive markings and do not attempt to hide from predators. This is possibly a case of honestly signalled aposematism.
A predator who manages to snag a pufferfish before it inflates will not feel fortunate for a long time to come. Almost all Pufferfish contain tetrodotoxin, a material that makes them foul-tasting and sometimes lethal to fish.
Tetrodotoxin is poisonous to humans, up to 1,200 times more toxic than cyanide. There is enough toxin in one Pufferfish to kill 30 adult humans, and there is no known antidote.
Distribution
They are the most diverse in the tropics, relatively scarce in the temperate region, and totally absent from cold waters. There are more than 120 species of Pufferfish worldwide.
Most of them are found in tropical and subtropical ocean waters, but some species live in brackish and even freshwater.
They’ve got long, tapered bodies with bulbous heads. Some wear wild markings and colours to advertise their toxicity, while others have more subdued or cryptic colouring to blend in with their surroundings.
They range in size from a 1-inch-long dwarf or pygmy pufferfish to a giant freshwater pufferfish, which can grow to more than 2 feet in length. They are scaleless fish and typically have rough to spicy skin. They all have four teeth that are fused together into a beak-like shape.
Diets
Pufferfish diets can differ depending on their climate. Traditionally, their diet consists mainly of algae and small invertebrates.
Larger species of Pufferfish can use their beak-like front teeth to crack open clams, mussels and other shellfish. Poisonous buffers are thought to synthesize their deadly toxin from the bacteria in the animals they feed.
They can live on a vegetarian diet if their environment lacks resources, but prefer an omnivorous variety of food. Some species of Pufferfish have introduced various hunting strategies, ranging from ambush to open-water hunting.
Environmental Threats
Some species of Pufferfish are considered vulnerable due to pollution, habitat loss and overfishing, but most populations are considered stable.
Ecology
Most pufferfish species live in marine or brackish waters, but some may enter freshwater. Approximately 35 species spend their entire lifecycle in freshwater.
These freshwater species are present in the disjointed tropical regions of South America (Colomesus asellus), Africa (six species of Tetraodon) and Southeast Asia (Auriglobus, Carinotetraodon, Dichotomyctere, Leiodon and Pao).
Reproduction
Many marine buffers have a pelagic or open-ocean life stage. Spawning happens as males slowly drive females to the surface of the water or when females are already present.
The eggs are spherical and bubbling. Hatching happens after approximately four days. The fries are small, but under magnification, they typically have a shape reminiscent of a pufferfish.
They have a working mouth and eyes, and they have to feed within a few days. Brackish-water buffers may breed in bays in a manner similar to marine species or may breed more similar to freshwater species in cases where they have migrated far enough upstream.
The reproduction of freshwater species varies quite a bit. The dwarf buffers court with males trailing females, likely showing crests and keels unique to this subgroup of species.
After the female acknowledges her advances, she will lead the male into a plant or another form of cover where she can release eggs for fertilization.
The male might be able to support her by rubbing her hand. This has been found in captivity and is the most frequently trapped buffer animal.
Target-group buffers were also spawned in aquariums, following similar courting behaviour, minus the crest/keel display. However, the eggs are laid on a flat piece of slate or other smooth, hard material to which they adhere.
The male keeps them safe until they hatch, carefully blowing water over them periodically to keep the eggs protected. His parenting is over when the young hatch and the fries are on their own.
Knowledge on the breeding of particular species is very small. T. Nigroviridis, a green-spotted buffer, has recently been artificially spawned under captive conditions.
It is suspected that they similarly spawn in bays to the saltwater species, as their sperm was found to be motile only at maximum marine salinity. Still, actual wild breeding has never been observed.
Xenopterus naritus was first artificially bred in Sarawak, Northwestern Borneo, in June 2016, the main aim of which was to grow the species in aquaculture.
In 2012, males of the species Torquigener albomaculosus were recorded carving large geometric, circular structures in the sand of the seabed in Amami arrivshima, Japan. The structures help to attract females and provide them with a secure place to lay their eggs.
Evolution
Pufferfish is estimated to have diverged from Porcupinefish between 89 and 138 million years ago. During the Cretaceous period, the four main clades diverged between 80 and 101 million years ago.
The oldest known pufferfish genus is Eotetraodon, from the Middle Eocene Europe Lutetian period, with fossils found in Monte Bolca and the Caucasus Mountains.
The species of Monte Bolca, E. Pygmaeus, coexisting with many other tetraodontiforms, including extinct diodontic species, primitive boxfish (Proaracana and Eolactoria) and other fully extinct forms, such as Zignoichthys and spinacanthides.
The extinct genus, Archaeotetraodon, is known from Miocene-aged fossils from Europe.
