A flatfish is one of the most remarkable—and, at times, confusing—fish in the ocean. Flatfish, with their two-dimensional shape and eccentric swimming patterns, can be found from the shallow waters of the world’s seas and oceans to the deep, murky depths.
Their strange form and behavior have been a source of fascination for millennia, as far back as ancient Greece, and numerous myths and legends have emerged as a result. But what exactly is a flatfish and how did it come to be?
Anatomy of a Flatfish
Flatfish, also known as pleuronectiforms, have the unique anatomy of being able to lie on the ocean floor. They possess both eyes on the same side of their heads and a flattened, asymmetric bodies. This means that one side of the fish is dark while the other is left colorless. Their particular shape enables them to not just lie on the seabed but also to travel across it.
Most flatfish have large mouths, in proportion to their bodies, that allow them to scoop up prey such as mollusks, crustaceans and fish. They also have an operculum, or hard cover, to protect their gills. The body usually comes equipped with two fins: one dorsal fin near the top, and one lower pectoral fin. With these fins, flatfish are able to swim in any direction, up to about 8 km/h.
Flatfish also possess a detachable jaw, which allows them to swallow their prey whole and keep from being detected by alert predators. Additionally, some flatfish have a getaway strategy when approached by predators, where they remove the fleshy skirt that covers their cheeks and scoot away using their fins.
The Evolution of the Flatfish
Flatfish have captured the attention of scientists since the 19th century, and recent advances in evolutionary biology have allowed us to piece together clues about their origins.
It’s thought that flatfish first evolved in the Early Cretaceous Era, right before the transition to the Late Cretaceous. During this time period, the continents of the world were shifting, with land bridges forming and migrating species passing through them.
We now know that the earliest flatfish to inhabit the seas were bony fish, and that from those bony fish, more advanced species eventually arose. It’s believed that the transition from swimming to crawling on the sea bed occurred in two steps. First, the shape of the bony fish developed so it could lie on the bottom. Then, one of the eyes migrated to the opposite side of the head.
Eventually, the first true flatfish came into existence, with an eye permanently located on the top side of their body. Flatfish have continued to evolve over time, leading to the various species of flatfish we see today.
Behavior of Flatfish
One of the most remarkable features of the flatfish is its unusual behavior. When first born, most flatfish are symmetrical, with both eyes on one side of the head. As they mature, however, one eye migrates to the other side. This shift allows the flatfish to remain hidden in the sand or mud of the ocean floor, with its back camouflaged.
Flatfish are adept at the art of camouflage, often laying perfectly still and blending into their environment. It’s also believed that their eyespots help to make them nearly invisible to predators. However, flatfish also engage in more active forms of defense such as changing their color to match the bottom of ocean.
Flatfish are some of the most fascinating creatures of the sea. With their unique body shape and behavior, they are an evolutionary marvel. From their asymmetrical bodies to their color changing tricks, flatfish demonstrate an impressive level of adaptation in order to survive in the deep ocean. It's no wonder they continue to capture the attention of scientists and spawn myths and legends.
Flatfish are a diverse family of fish with a unique and specialized anatomies and life history. Flatfish are among the most popular types of seafood and can be found in many cuisines around the world. But how does a flatfish ultimately make its way to your dinner plate? This blog will explore the life cycle of flatfish and the amazing journey they take from spawning to dinner plate.
Flatfish begin their lives as small, semi transparent eggs. These eggs are only slightly larger than grains of salt and in many species, the female flatfish will produce thousands of eggs at a single spawning event. After being expelled into the water, the eggs settle to the seafloor or estuarine environment, where they will remain in a state of suspended development until they are ready to hatch. Depending on the species, this process can take between 2-6 days.
Once hatched, the newly emerged larva are extremely vulnerable. The larva must swiftly develop from this small, weak, semi-transparent form into a juvenile flatfish suitable for survival in the wild. During this transformation, the larva are constantly at risk of predation from other fish, crabs and seabirds.
Settlement and Maturation
Once a larva has grown for a few weeks, it attempts to settle in the seabed. This is a critical and dangerous time for the flatfish, as it is the most vulnerable to predators. Eventually the larva finds a suitable location to settle, such as a crevice or sandy bottom. After settling, the juvenile flatfish begins to further develop and grow. This is accompanied by a physiological transformation, with the right eye migrating to the left side of the head. This process is known as “metamorphosis”, and is the defining characteristic of all flatfish species. At this point, the flatfish begins feeding on the invertebrates living in the sea floor, such as clams, worms and small fish.
Growth and Maturity
Flatfish reach their maximum size at quite a young age; most species reach maturity after at most 1 – 3 years. From this point, the flatfish will continue to grow for the remainder of their lives. Depending on species, flatfish can reach up to 9 meters in length, with ages up to 100 years old. Flatfish have a relatively long lifespan, meaning that once mature, they may spend decades living in the same area and contributing to the local reef ecosystem.
After a flatfish has matured and reached a suitable size, it is often captured by fishermen. Flatfish are a popular and sought after target for fishermen for their meat, oil and roe. Flatfish are often taken by trawlers, or netting vessels that drag large nets along the seafloor, as well as hook-and-line vessels which use baited hooks to catch individual fish. The vast majority of flatfish caught in these fisheries are semi-mature juveniles.
Processing and Preparation
Once caught, flatfish are brought to shore for processing. In some cases, the flatfish are sold live and brought to restaurants or markets directly, where they may be eaten as is or further prepared for consumption. More often, however, the flatfish are processed and frozen for later sale. This begins with gutting the fish, and cleaning and weighing the fillets. Next, the fillets are placed in a brine, which helps to preserve the flesh and preserve its texture. Finally, the fillets are skinned, portioned, packaged and frozen.
Once processed and prepared, the flatfish is shipped to its final destination. This may be a local grocery store or restaurant, or even another country. Flatfish are shipped in convoy with other types of seafood, or even with fruits and vegetables, depending on the route. Flatfish may be shipped on a plane or a ship, both of which require strict temperature and humidity control.
Preparation and Cooking
Once the flatfish reaches the final destination, it is ready for purchase and consumption. The most popular preparation method for flatfish is to filet the fish, which involves removing the head, tail and any sharp bones from the fillet using a sharp knife. The fillet is then seasoned with spices, oils and herbs, if desired. Finally, the fillet is cooked - usually by baking, grilling, steaming, pan-searing or frying.
Flatfish can journey from spawning grounds to final destination with remarkable speed and efficiency. The journey of flatfish, beginning as an egg and lasting up to one hundred years, is a testament to the wondrous biodiversity of the ocean. While the life cycle and journey of the flatfish may differ depending on the species and region, the process ultimately culminates in the same outcome - a delicious seafood meal.
|Vitamin A||0.012 mg|
|Vitamin D||0.0035 mg|
|Vitamin D3||0.0035 mg|
|Vitamin E||0.77 mg|
|Vitamin K||0.1 ug|
|Vitamin B1||0.03 mg|
|Vitamin B2||0.03 mg|
|Vitamin B3||0.00128 grams|
|Vitamin B4||0.0799 grams|
|Vitamin B5||0.23 mg|
|Vitamin B6||0.12 mg|
|Vitamin B9||0.006 mg|
|Vitamin B12||0.00131 mg|
Daily Value 1.3 g
Daily Value 0.018 g
Daily Value 0.4 g
Daily Value 1.25 g
Daily Value 4.7 g
Daily Value 2.3 g
Daily Value 0.011 g
Daily Value 0.9 mg
Daily Value 0.0023 g
Daily Value 0.055 mg
|Aspartic Acid||1.698 grams|
|Glutamic Acid||2.614 grams|
|Total Sugars||0 ug||
|Lauric acid (12:0)||0.01 grams||
|Myristic acid (14:0)||0.11 grams||
|Palmitic acid (16:0)||0.35 grams||
|Stearic acid (18:0)||0.07 grams||
|Total Saturated fatty acids:||0.54 g|
|Oleic acid (18:1)||0.44 grams||
|Palmitoleic acid (16:1)||0.11 grams||
|Gadoleic acid (20:1)||0.07 grams||
|Total Monounsaturated fatty acids:||0.62 g|
|Omega-3 Timnodonic acid (20:5)||0.17 grams||
|Omega-3 Clupanodonic acid (22:5)||0.03 grams||
|Omega-6 Eicosadienoic acid (20:2)||0.01 grams||
|Linolenic acid (18:3)||0.02 grams||
|Linoleic acid (18:2)||0.06 grams||
|Total Polyunsaturated fatty acids:||0.29 g|
|Total Sterols:||0.06 g|