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The common name for a number of marine flatfish, a flounder is a demersal fish found at the bottom of seas or lakes. All members of its order, Pleuronectiformes, contribute value to the ecosystem and humans, as they are integral in marine food chains and are a valuable food dish, prepared whole or in fillets.
See the fact file below for more information on the flounder or alternatively, you can download our 20-page Flounder worksheet pack to utilise within the classroom or home environment.
Key Facts & Information
- Flounders are a type of flatfish, a very unique group wherein adults are not bilaterally symmetrical, the only fish with this asymmetry and the only vertebrates that differ from the bilaterally symmetrical body structure. The young flatfish are bilaterally symmetrical and swim in a vertical manner just like other fish, but early in development, one of their eyes moves to the other side of the cranium, across the upper part of the skull, and sticks itself adjacent to the eye on the other side. Flatfish swims with both eyes on the upper side and the lower side is blind. The metamorphosis also turns the upper side vibrantly pigmented and the lower side light-colored, and changes in dentition and fin placement.
- Most species turn either their “left” face upward (both eyes on the left side and lie on the right side) or face their “right” side upward, but some species are oriented either way, such as the starry flounder (Platichthys stellatus).
- Its body is highly compressed, relatively flat on the blind side, and rounded on the eyed side.
- The other unique features of this order are having protrusible eyes, or those that can be extended or protruded, being able to live on the seabed, and extending their dorsal fin onto the head.
- Most of the time, adults lack a swimming bladder.
- They are considered carnivorous and benthic.
- Flatfish have a number of names, such as flounder, sole, plaice, halibut, dab, and turbot. There are about 570 living species in the Pleuronectiformes order, classified in 123 genera and 11 families. They are almost solely marine, but there are about four species that are found in freshwaters.
FLOUNDER CLASSIFICATION AND CHARACTERISTICS
- The term “flounder” is a common name, describing several geographically and taxonomically unique species.
- In general, flounders belong to these families: Achiropsettidae (southern flounders), Bothidae (left-eye flounders), Paralichthyidae (large-tooth flounders), Pleuronectidae (right-eye flounders), and Psettodidae (spiny flounders).
- Left-eye flounders inhabit the Atlantic, Indian, and Pacific Oceans. Their eyes are sinistral or are located on the left side, and their pelvic fin base on the eyed side is longer than on the blind side.
- Right-eye flounders live in the Arctic, Atlantic, Indian, and Pacific Oceans, and some are occasionally found in brackish water and rarely in freshwater. Their eyes are usually dextral or are positioned on the right side, and they do not have oil globules in the yolk of their eggs.
- Large-tooth flounders swim in the Atlantic, Indian, and Pacific Oceans. Their eyes are sinistral, with their pelvic fin bases short and almost symmetrical, and their pectoral fins branches.
- Southern flounders are spotted in the Southern Hemisphere, Antarctic, and sub-antarctic regions. Their eyes are also located on the left side, with their bodies extremely compact, and their pectoral fins rudimentary or absent.
- Spiny flounders inhabit western Africa and the Indo-West Pacific. They are known for their pelvic fins with a single spine and five soft rays.
- Flounder sizes range from five to 15 inches, although there are instances when they grow as large as three feet in length. Their width is about half their length. All flounder families, except spiny flounders, do not have spines in their fins; all of the fin rays are soft.
- Flounders are known to be ambush predators at the soft mud of the bottom of the sea, near bridge piles, and docks, and are sometimes seen on bass grounds. They feed on fish spawn, crustaceans, polychaetes, and small fish.
- Flounders are preyed by predators at all stages. Their eggs and larvae are consumed by jellyfishes, ctenophores, shrimps, and fish. Crabs, shimprs, and fish feed on young and newly-settled flounders while different predatory fish, even birds, seals, and sea lions, prey on juveniles and adult flounders.
- Some flounder species are able to camouflage, changing colors and patterns of their skins to match the backgrounds on which they lie.
DISTRIBUTION, USES, AND THREATS
- Flounders swim in all oceans worldwide, ranging from shallow waters to deep water habitats, with the majority in areas ranging from nearshore to depths of about 100 meters on the continental shelf.
- In some studies, among all sea creatures, flounders were spotted at the bottom of the Marianas trench, considered as the deepest location on the earth’s crust. Swiss scientist Jacques Piccard and U.S. Navy Lt. Don Walsh arrived at about 10,900 meters deep and discovered soles or flounders 30 centimeters long, together with shrimp.
- Flounders are widely caught for food, such as the medium-sized and large fish, and even smaller species of flounders are eaten. This has resulted in threats to their numbers that were estimated to be only about ten percent of pre-industrial levels in 2003, caused mainly by overfishing and commercial fishing.
This is a fantastic bundle which includes everything you need to know about the flounder across 20 in-depth pages. These are ready-to-use Flounder worksheets that are perfect for teaching students about the flounder which is a demersal fish found at the bottom of seas or lakes. All members of its order, Pleuronectiformes, contribute value to the ecosystem and humans, as they are integral in marine food chains and are a valuable food dish, prepared whole or in fillets.
Complete List Of Included Worksheets
- Flounder Facts
- Finding Flounder
- Tastiest Fish in the Sea
- Classify That Flatfish
- Finteresting Facts
- Facts in the Tank
- Fishy Questions
- Economic Importance
- Is Flounder a Flounder
- Flounder Life Cycle
- What’s Cooking?
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Link will appear as Flounder Facts & Worksheets: https://kidskonnect.com - KidsKonnect, February 17, 2021
Use With Any Curriculum
These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.