swellfish

Swellfish is a common name used to refer to several species of fish that have the ability to inflate their bodies. This inflation is a defense mechanism, allowing the fish to appear larger and more difficult for predators to swallow. The most well-known examples of swellfish belong to the family Tetraodontidae, commonly known as pufferfish. These fish possess a specialized stomach that can rapidly fill with water or air, causing their bodies to distend significantly. The process of inflating can take a matter of minutes, and the fish will often remain in this inflated state until the threat has passed.

The ability to swell is not exclusive to pufferfish. Other families of fish, such as the porcupinefish (Diodontidae), also exhibit this characteristic. Porcupinefish, however, typically have spines that become erect when they inflate, adding an extra deterrent to potential predators. While the swelling mechanism is primarily for defense, it can also be triggered by stress or agitation. The rapid inflation can make the fish too large to fit into the mouths of many predators, offering a significant survival advantage.

Many species of swellfish are also known for their toxicity. The toxin, tetrodotoxin, is found in various organs and is particularly concentrated in the liver and ovaries. This toxin is highly potent and can be lethal to humans and other animals if ingested. Due to this toxicity, certain swellfish, like the fugu from Japan, are considered a delicacy but require highly skilled preparation by licensed chefs to remove the poisonous parts. Not all swellfish are toxic, however, and the level of toxicity varies greatly by species and geographic location.