flounder

flounder facts

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Flounder has a very thin body, and the flounder lives up to its name.

The flounder lies almost motionless in the sandy ocean or on the bottom of the ocean, patiently waiting for a tasty treat to arrive so it can feed. Its entire lifestyle and appearance revolve around the bottom habitat. It's an incredible display of evolutionary ingenuity. But some flounder species are in danger of being depleted due to their popularity as a delicacy.

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5 Unbelievable Flounder Facts!

  • The technical term for the type of benthic marine animal is demersal fish.
  • Certain species of flounder are known as marine chameleons because of their ability to change color to blend in with their environment.
  • Flounders are born similar to typical fish. A few weeks later, it underwent a profound metamorphosis and became a flounder.
  • Flatfish probably evolved 50 million years ago. A fossil from that period suggests that certain species of flounder had evolved an eye on the top of their head.
  • As a delicacy, halibut is usually grilled or broiled.

scientific name

The word flounder is not really the scientific name. This often causes quite a bit of confusion among people. Instead, it refers to the many different species of flounder that belong to four distinct families: Achiropsettidae, Pleuronectidae, Paralichthyidae, and Bothidae. All of these families are classified under the order Pleurophytes. However, not every member of this order is a flounder, as it also includes dabs, brills, sole, etc. Together these creatures belong to the group of ray-finned fishes known as Actinopterygii.

Flounder camouflaged on the bottom of the sea
There are hundreds of species of flounder – flounder are usually divided into right-eye and left-eye families.

© Moondigger/Creative Commons

species

Plaice are generally divided into right-eye and left-eye families. The right-eyed family of Pleuronectidae contains about 100 different species. The left eye family of Bothidae and Paralichthyidae contains about 240 species. A fourth family, Achiropsettidae, has only a few species. Here are a few examples of common flounder species:



  • European Flounder: This species occupies a large territory between the North African coast in the west, the Black Sea in the east, and the Baltic Sea in the north. The species is so popular as a food source that it has also been introduced to North American waters. The body is olive green or light brown, almost diamond-shaped when finned.
  • Summer Flounder: This fish is found along the Atlantic coast of the United States and Canada. It has dark gray or brown and rounded fins.
  • Dusky Flounder: Up to 12 inches long, this species has a very elongated appearance with tan or brown scales. It is located in a body of water between the Gulf of Mexico and the Yucatan Peninsula.
  • Winter flounder: Also known as blackback flounder, is a right-eyed flounder native to coastal waters along the western North Atlantic coast — from Labrador in Canada to Georgia in the United States.
  • Peacock flounder: Also known as flower flounder, this flounder is blue, pink, and yellow, like the sand in the shallow Indo-Pacific waters where it lives.
  • European Plaice: This right-eye flounder is known for its sweet and mild flavor and firm, juicy texture. It inhabits the muddy bottom of the European continental shelf from the Barents Sea to the Iberian Peninsula and around Iceland.
  • Arrowtooth flounder: This is the most common fish in the Gulf of Alaska and can be caught as far south as Santa Rosa, California. It is named for its menacing set of sharp, arrow-shaped teeth.
  • Olive flounder: This rare flounder is also known as Korean flounder, Korean flounder, or Japanese flounder. It is a large flounder native to the Pacific Northwest made popular by the game Animal Crossing.
  • Atlantic flounder: These flounder are now endangered due to overfishing. They live on sand, gravel, or clay bottoms at depths from 50 to 2,000 miles. They are found throughout the North Atlantic, including Greenland and Virginia in the west and Iceland and Europe in the east.
  • Gypsophila flounder: Also known as millstone, grinding wheel, and long-nosed flounder, this common fish is found around the North Pacific Ocean.
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A small flounder is alone around a coral
Just like flounder started life as common fish 65 million years ago before they evolved – they started life the same way today.

©Gaurav Ruke/Shutterstock.com

evolution

Flounders in the flounder family are some of the most asymmetrical animals on the planet — and believe it or not, they're not born that way. They start their lives as ordinary small fish with swim bladders and eyes on the sides of their heads, before turning into the exotic Picasso fish adult form. In an evolutionary snapshot, their eyes moved to the top, their swim bladders shrunk, and their fins became all but useless in a matter of weeks. They start life as lively little fish, and then sink to the bottom of the sea, "struggling" on the bottom of the sea.

All of these strange forms began about 65 million years ago—and within 3 million years, their evolution was largely complete. Three million years, in the time of evolution, is just the blink of an eye. The flounder species are so diverse that it's nearly impossible for scientists to trace the degree of integration between the different regions of the skull over the 65-million-year history of flounder and their relatives without creating complex mathematical models. They found that, in flatfish, the evolution of the asymmetry involved changes throughout the skull. As the eye migrates – other changes happen, it becomes additive.

Still can't explain why flatfish like flounder change so quickly and dramatically, almost violently — while fish like stingrays just flatten out gradually. Sometimes nature's weirdness is what's most magical about it.

The flounder has a flat body and two large eyes protruding from a small stalk on the same side of the head.

©Becky Gill/Shutterstock.com

appearance

Flounders have an unusually flat appearance, well suited to their bottom-dwelling lifestyle. To see everything above it, the flounder has two large round eyes that protrude from a small stalk on the same side of the head. These eyes can also move independently of each other.

Typical flounder specimens are between 5 and 25 inches long (the largest flounder specimen recorded was about 37 inches) and can weigh up to 22 pounds. However, this doesn't quite reflect its true size, as the flatfish's round or oval body gives it a lot of surface area.

The flounder's scales act as camouflage, making it difficult for both predators and prey to spot it on muddy or sandy bottoms. Some species can actively change color to blend in with the ocean floor. This serves a dual purpose and also indicates the emotional state of the fish. For example, a pale color may indicate that the creature feels threatened.

Flounder comes in a variety of different colors and patterns, depending on the composition of the sediment it's in. Orange, brown, green, white or tan slate is normal.

Flounder camouflaged on the bottom of the sea
Flounders can camouflage themselves perfectly on the ocean floor.

© Requiem for the Dark Jedi – Public Domain

Distribution, Population and Habitat

Flounder inhabit the bottom of the ocean near piers, bridges and coral reefs. Its main occupation areas include tropical and temperate seas off the coasts of Europe, North America, Africa and Asia. Some species also live further north near the Arctic.

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An estimated 30 million flounder remain in the world's oceans, but pollution, habitat change and overfishing in the 20th and 21st centuries have depleted some populations. For many flounder species, there are insufficient data to fully estimate their conservation status. But when the data were available, the vast majority of species appeared to be in good health.

Conservation trackers are considered least of concern by the IUCN Red List. However, continued depletion of fish stocks could threaten many species in the future.

In the United States, NOAA is the primary government agency responsible for carefully managing flounder populations. The administration uses scientific data to determine how much flounder populations can be caught the following year, and then allocates resources accordingly between commercial and recreational fishing to ensure there are enough stocks to repopulate the waters.

diet

Flounder eat shrimp, crustaceans, worms, plankton, etc.

predator and prey

Flounders are primarily nocturnal carnivores, feeding on shrimp, crab, and other fish. Smaller species may also eat worms and plankton. The exact composition of the diet varies by location and species. Flounders are ambush predators that lie motionless in the ocean or on the bottom of the ocean, blending in with their surroundings before quickly snapping down their razor-sharp teeth on unsuspecting prey.

Due to their large size, flounder have only a few predators such as sharks, eels and humans. Camouflage provides the best means of protection. However, when exposed, it is very vulnerable to larger predators due to its lack of other natural defenses.

Gulf Flounder
Flounder breed in the warmer months when food is plentiful.

©Porco_Rosso/Shutterstock.com

Reproduction and Lifespan

Breeding season for flounder typically occurs during the warmer months. Females release more than 100,000 (sometimes millions) of eggs from their bodies, and males release sperm to fertilize them. After a few weeks, the juveniles will hatch from the eggs. Spawning usually coincides with the most productive and plentiful time of year for food.

At birth, a flounder looks like a typical fish. It is born with a standard symmetrical appearance, with eyes on the sides of the head, and it also swims in the ocean like a fish.

After a few days, the flounder will undergo significant physical changes, the body begins to flatten, the swim bladder (which provides buoyancy) disappears, and one eye begins to move to the other side of the fish. Once fully developed, flounder can often live for 3 to 10 years in the wild.

european halibut
Flounder is caught, cooked and enjoyed in delicacies all over the world.

©Michele Ursi/Shutterstock.com

fishing and cooking

Caught for both recreational and commercial purposes, flounder are one of the most popular deep-sea fishes in the world. It's usually fried, grilled, or broiled, but it can be cooked in so many ways and with so many foods that the variety is astounding. The mild flavor goes well with a variety of sauces, herbs, spices, vegetables and cheeses.

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about the author

Lisa Pace


After a career providing opportunities for local communities to experience and create art, I enjoy having time to write about two of my favorite things – nature and animals. I spend half my life outside, usually with my husband and adorable 14 year old puppy. We enjoyed walking around the lake and taking photos of the animals we encountered including: otters, osprey, Canada geese, ducks and nesting bald eagles. I also enjoy reading, discovering books to add to my library, collecting and playing vinyl records, and listening to my son's music.

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Flounder FAQs (Frequently Asked Questions)

What do flounder eat?

Flounder are very common prey for sharks, eels and humans.

Where do flounder live?

Flatfish tend to live at the bottom of the seabed in coastal areas, near man-made structures such as piers and bridges, as well as natural structures such as coral reefs.

Is halibut a good fish to eat?

Flounder is known to contain high-quality lean meat, low in fat (except healthy omega-3 fats) and high in protein. Studies show that it may help reduce the risk of heart disease.

What does halibut taste like?

Halibut has a sweet and subtle flavor that goes well with its flaky and crumbly texture. It is usually roasted or broiled.

What is the difference between Halibut and Flounder?

The difference between flounder and halibut confuses many people. Simply put, halibut is a member of the flatfish family. This actually makes it a type of flounder. But the halibut is larger than the common flounder and lives further north in Alaska.

Are flounder herbivores, carnivores, or omnivores?

Flounders are carnivores, which means they eat other animals.

To which kingdom do flounder belong?

Flounder belongs to the animal kingdom.

What class do flounder belong to?

Flounder belongs to the class Actinopterygii.

What phylum do flounder belong to?

Flounders belong to the phylum Chordate.

What family do flounder belong to?

Flounders belong to the flounder family.

What order do flounder belong to?

Flounders belong to the order Pleuronectiformes.

What genus do flounder belong to?

Flounders belong to the flounder genus.

What type of mulch do flounder have?

Flounders are covered with scales.

What are some interesting facts about flounder?

Flounder is a flat fish that lives in the Atlantic and Pacific Oceans!

What is the scientific name of flounder?

The scientific name for flounder is Paralichthys.

What are the distinguishing features of flounder?

Flatfish have a flattened body.

What is the lifespan of flounder?

Flounder live on average from 3 to 10 years.

What is the biggest threat to flounder?

The biggest threat to flounder is overfishing.

What is the optimal pH for Flounder?

The optimum pH for flounder is between 6.5 and 8.0.

What is another name for flounder?

Flounder is also known as flounder.

How many halibuts are left in the world?

There are approximately 30 million flounder in the world.

How do flounder give birth?

Flounder spawn.

What is the difference between halibut and cod?

The main differences between cod and flounder are their size, appearance, hunting methods and breeding strategies.

What is the difference between tilapia and flounder?

The key differences between flounder and tilapia are their classification, habitat, appearance, diet, and their uses in aquaculture and cooking. These fish belong to different orders and families. They live in unique habitats and have personality traits and diets that are well suited to them.

What is the difference between haddock and halibut?

The difference between haddock and flounder is appearance, size, diet, distribution, predators, reproduction and lifespan.

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source
  1. David Burnie, Dorling Kindersley (2011) Animals, The Definitive Visual Guide to the World's Wildlife
  2. Tom Jackson, Lorenz Books (2007) Encyclopedia of World Animals
  3. David Burney, Kingfisher (2011) The Animal Encyclopedia of Kingfishers
  4. Richard Mackay, University of California Press (2009) Atlas of Threatened Species
  5. David Burnie, Dorling Kindersley (2008) Illustrated Animal Encyclopedia
  6. Dorling Kindersley (2006) Dorling Kindersley Animal Encyclopedia
  7. Encyclopedia Britannica, available here: https://www.britannica.com/animal/flounder
  8. Soft Schools, available here: https://www.softschools.com/facts/animals/flounder_facts/1400/
  9. Fishing Booker, available here: https://fishingbooker.com/blog/halibut-vs-flounder-all-you-need-to-know/