The term odd-shaped swimmers is used for denoting a large and diverse group of fish species, most of them belonging to different taxonomic ranks, but still being linked by a number of characteristics.
The category of odd-shaped swimmers being so large, the majority of the included species do not even inhabit the same waters, though most of them prefer shallow waters and the abundance of food provided by coral reef areas. Many of the oddest species live in the Atlantic Ocean and in the Indo-Pacific region, some of them live in Mediterranean, and there are some that migrate over long distances.
There are so many type of fish that simply look strange – some of them are round, others spear-shaped or even angular, but none of them looks like fish in the traditional sense of the word. Here are some of the strangest of them all:
Triggerfish – these relatively large fish (they can reach a maximum length of about 50 centimeters) have a compressed body, a disproportionately large head with strong jaws and tiny eyes on the top of the head. They received their name from a defense method that they use – they have two dorsal spines they can erect to scare away predators, but the first one locks into place only when the second, shorter spine comes up, too and during unlocking, it is the second spine that needs to be depressed first;
Pufferfish – these highly poisonous vertebrates are usually quite small and can be found in tropical and temperate waters. They were also named based on their preferred method of self-defense: when they feel threatened, they fill their elastic stomachs with water, increasing in size and becoming spherical;
Boxfishes – these fish are covered in hexagonal scales and have an angular shell that gives them a box-like appearance;
Trumpetfish and cornetfish – two distinct families, but looking almost identical, both having thin, elongated bodies and long snouts.
Almost all odd-shaped swimmers are clumsy, their strange body shape making them slow in the water. Not being good swimmers, they have all developed special defense mechanisms to protect themselves. Some of them are poisonous – most of them are not nearly as dangerous as the pufferfish, but boxfishes, for example, cover themselves in a toxic mucus when stressed, while others, such as the triggerfish, have very powerful teeth and they bite not only larger fish, but humans, too. Many species, such as the goatfish, are able to change color very quickly, allowing them to blend into the sand when they sense danger approaching, while others, such as the long, thin and almost transparent shrimpfish usually stay together and float in groups for more safety.
Most odd-shaped swimmers are carnivorous. They usually prefer shallow waters, so their diet consists mainly of the tiny invertebrates and small fish they find there.