By: Sam Nowinski

 Unique fish adaptations are one of the most overlooked yet fascinating things to learn about. If you’ve ever wondered why there are so many different sizes, shapes, and colors of fish then you’ve come to the right place!

Adaptation is a crucial component to an organism’s survival and over time, different fish species have adapted to fit their distinctive environment.  For example, caudal fin (tail) shape and size is one distinguishing characteristic for these types of animals. Fish with a long and forked caudal fin are typically the faster swimmers; such as sharks, tuna, and swordfish. Fish with shorter and more rounded caudal fins are the fish we see hiding in crevices, dwelling on the bottom, or engaging in slow swimming motions; these include pufferfish, clownfish, and wrasse.  

Body shape is another distinguishing characteristic among fish species is body shape. Fish with a fusiform body shape, or a streamlined torpedo shaped body, are those found in the open water moving around with little effort. These fish typically include most species of sharks, bonito, and mackerel. Fish with a dorsoventrally depressed (flattened) body are the bottom dwellers with a wide and flat profile; this group of fish included skates, rays, and flounder. Fish with an anguilliform (eel-like) body shape are flexible and move with a series of waves from head to tail; these include the eel-like fish. Fish with a globiform body shape are the very slow swimming, round fish often with a special defense strategy to offset their slow speed, like the pufferfish and lump sucker.

Mouth positioning is also a defining characteristic of an animal in its habitat. Some animals have an inferior or sub-terminal mouth located on the underside of their head. This allows them to eat food below their bodies as they naturally swim through their environments. These fish include sharks, rays, and catfish. In contrast, animals that eat food above them have a superior mouth, allowing them to come from below their pray for easy capture. These are typically ambush predators and surface feeders, such as tarpon.  Fish that don’t fit either of these categories can also have a terminal mouth position located in the center of their head to capture prey from head on, or protrusible mouth position allowing the fish to protrude their jaw for easy food intake.

Besides mouth, tail, and body shape, fish may also possess behavioral adaptations too. Many fish have spines, barbs, or fangs for defense. There are even fish that display warning colors to warn predators of their toxicity. Some fish are known as sequential hermaphrodites, meaning they can swap genders. Other fish are masters of camouflage and can alter their color pigments to blend in with their surroundings.

The amount of fish adaptations are truly endless, so next time you catch a fish or spot a fish in the wild be sure to notice all of its physical characteristics and think about how it has evolved to be a perfect fit for the environment it is in!