The puffer's unique and distinctive natural defenses help compensate for its slow locomotion.
It moves by combining pectoral, dorsal, anal, and caudal fins.
This makes it highly maneuverable, but very slow, and therefore 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, tasty fish.
 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.
Takifugu oblongus, for example, is a fugu puffer that is not poisonous, and toxin level varies widely even in fish that are.
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, and make no attempt to hide from predators.
This is likely an example of honestly signaled aposematism.

Dolphins have been filmed expertly handling pufferfish amongst themselves in an apparent attempt to get high or enter a trance-like state.
The puffer's unique and distinctive natural defenses help compensate for its slow locomotion. It moves by combining pectoral, dorsal, anal, and caudal fins. This makes it highly maneuverable, but very slow, and therefore 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, tasty fish.  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. Takifugu oblongus, for example, is a fugu puffer that is not poisonous, and toxin level varies widely even in fish that are. 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, and make no attempt to hide from predators. This is likely an example of honestly signaled aposematism.
Dolphins have been filmed expertly handling pufferfish amongst themselves in an apparent attempt to get high or enter a trance-like state.
Tetraodontidae