Most pufferfish species live in marine or
brackish waters, but several tropical genera, comprising about 35 species, spend their entire lifecycles in fresh water. These freshwater species are found in disjunct tropical regions of South America (
Colomesus asellus and
Colomesus tocantinensis), Africa (six
Tetraodon species), and Southeast Asia (
Auriglobus,
Carinotetraodon,
Dichotomyctere,
Leiodon and
Pao).
Natural defenses The puffer's unique and distinctive natural defenses help compensate for its slow locomotion. It moves by combining
pectoral,
dorsal,
anal, and
caudal fin motions. This makes it highly maneuverable, but very slow, so a comparatively easy predation target. Its tail fin is mainly used as a rudder, but it can be used for a sudden evasive burst of speed that shows none of the care and precision of its usual movements. The puffer's excellent eyesight, combined with this speed burst, is the first and most important defense against predators. The pufferfish's secondary defense mechanism, used if successfully pursued, is to fill its extremely elastic
stomach with water (or air when outside the water) until it is much larger and almost
spherical in shape. Even if they are not visible when the puffer is not inflated, all puffers have pointed spines, so a hungry predator may suddenly find itself facing an unpalatable, pointy ball rather than a slow, easy meal. Predators that do not heed this warning (or are "lucky" enough to catch the puffer suddenly, before or during inflation) may die from choking, and predators that do manage to swallow the puffer may find their stomachs full of
tetrodotoxin (TTX), making puffers an unpleasant, possibly lethal, choice of prey. This
neurotoxin is found primarily in the
ovaries and
liver, although smaller amounts exist in the
intestines and
skin, as well as trace amounts in muscle. It does not always have a lethal effect on large predators, such as sharks, but it can kill humans. Larval pufferfish are
chemically defended by the presence of TTX on the surface of skin, which causes predators to spit them out. Not all puffers are necessarily poisonous; the flesh of the
northern puffer is not toxic (a level of poison can be found in its
viscera) and it is considered a delicacy in North America. Toxin level varies widely even in fish that are poisonous. A puffer's neurotoxin is not necessarily as toxic to other animals as it is to humans, and puffers are eaten routinely by some species of fish, such as
lizardfish and
sharks. Puffers are able to move their eyes independently, and many species can change the color or intensity of their patterns in response to environmental changes. In these respects, they are somewhat similar to the terrestrial
chameleon. Although most puffers are drab, many have bright colors and distinctive markings,
Dolphins have been filmed expertly handling pufferfish amongst themselves in an apparent attempt to get intoxicated or enter a trance-like state.
Reproduction Many marine puffers have a
pelagic, or open-ocean, life stage. Spawning occurs after males slowly push females to the water surface or join females already present. The eggs are spherical and buoyant. Hatching occurs after roughly four days. The fry are tiny, but under magnification have a shape usually reminiscent of a pufferfish. They have a functional mouth and eyes, and must eat within a few days. Brackish-water puffers may breed in bays in a manner similar to marine species, or may breed more similarly to the freshwater species, in cases where they have moved far enough upriver. Reproduction in freshwater species varies quite a bit. The
dwarf puffers court with males following females, possibly displaying the crests and keels unique to this subgroup of species. After the female accepts his advances, she will lead the male into plants or another form of cover, where she can release eggs for fertilization. The male may help her by rubbing against her side. This has been observed in captivity, and they are the only commonly captive-spawned puffer species. Target-group puffers have also been spawned in aquaria, and follow a similar courting behavior, minus the crest/keel display. Eggs are laid, though, on a flat piece of slate or other smooth, hard material, to which they adhere. The male will guard them until they hatch, carefully blowing water over them regularly to keep the eggs healthy. His parenting is finished when the young hatch and the fry are on their own. In 2012, males of the species
Torquigener albomaculosus were documented while carving large and complex geometric, circular structures in the seabed sand in
Amami Ōshima, Japan. The structures serve to attract females and to provide a safe place for them to lay their eggs. Information on breeding of specific species is very limited.
T. nigroviridis, the green-spotted puffer, has recently been spawned artificially under captive conditions. It is believed to spawn in bays in a similar manner to saltwater species, as their sperm was found to be motile only at full marine salinities, but wild breeding has never been observed.
Xenopterus naritus has been reported to be the first bred artificially in Sarawak, Northwestern Borneo, in June 2016, and the main purpose was for development of aquaculture of the species.
Diet Pufferfish diets can vary depending on their environment. Traditionally, their diet consists mostly of algae and small invertebrates. They can survive on a completely vegetarian diet if their environment is lacking resources, but prefer an omnivorous food selection. Larger species of pufferfish are able to use their beak-like front teeth to break open clams, mussels, and other shellfish. Some species of pufferfish have also been known to enact various hunting techniques ranging from ambush to open-water hunting. File:Arothron hispidus Prague 2011 1.jpg|
White-spotted puffer File:Arothron manilensis.jpg|
Striped puffer File:Giant Puffer fish skin pattern.JPG|Elaborate
skin pattern of the
giant or mbu puffer == Evolution ==