The starry flounder (''Platichthys stellatus''), also known as the grindstone, emery wheel and long-nosed flounder, is a common
flatfish
A flatfish is a member of the Ray-finned fish, ray-finned demersal fish order (biology), order Pleuronectiformes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the ...
found around the margins of the
North Pacific
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
.
The distinctive features of the starry flounder include the combination of black and white-to-orange bar on the
dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal co ...
and
anal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
s, as well as the skin covered with
scales
Scale or scales may refer to:
Mathematics
* Scale (descriptive set theory), an object defined on a set of points
* Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original
* Scale factor, a number w ...
modified into tiny star-shaped plates or
tubercle
In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal.
In plants
A tubercle is generally a wart-like projection ...
s (thus both the common name and species epithet), resulting in a rough feel. The eyed side is black to dark brown, while the lower side is white or cream-colored. Although classed as "righteye flounders," individuals may have their
eyes on either the right or left side. They have been recorded at up to 91 cm and 9 kg.
Starry flounders are inshore fish, ranging up
estuaries
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...
well into the
freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
zone, to the first
riffle
A riffle is a shallow landform in a flowing channel. Colloquially, it is a shallow place in a river where water flows quickly past rocks. However, in geology a riffle has specific characteristics.
Topographic, sedimentary and hydraulic indica ...
s, with young found as much as 120 km inland. In marine environments, they occur as deep as 375 m. They glide over the bottom by rippling their dorsal and anal fins, feeding on a variety of
benthic
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...
invertebrates. Larvae start out consuming
plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
ic
alga
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mi ...
e and
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
s, then as they metamorphose they shift to larger prey.
Like all flounders, when they are young, starry flounders swim around like normal fish in a vertical position, but soon they begin to tilt to one side as they swim and eventually live lying on the sandy floor. As well as many other changes in body structure, the migration of one of the eyes to the other side of the head is one of the most crucial changes. Other changes include the loss of dark color on the under side.
On the western side of the Pacific they occur as far south as
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
and
Korea
Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
, ranging through the
Aleutian Islands
The Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi language, Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a cha ...
, the coast of
Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...
,
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
, and down the
West Coast West Coast or west coast may refer to:
Geography Australia
* Western Australia
*Regions of South Australia#Weather forecasting, West Coast of South Australia
* West Coast, Tasmania
**West Coast Range, mountain range in the region
Canada
* Britis ...
of the U.S. as far as the mouth of the
Santa Ynez River
The Santa Ynez River is one of the largest rivers on the Central Coast of California. It is long, ArcExplorer GIS data viewer. flowing from east to west through the Santa Ynez Valley, reaching the Pacific Ocean at Surf, near Vandenberg Space Fo ...
in
Santa Barbara County, California
Santa Barbara County, California, officially the County of Santa Barbara, is located in Southern California. As of the 2020 census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa Maria.
Santa Barba ...
. They are an important game and
food fish
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingest ...
across their range.
Morphology
The starry flounder has an oval shaped body with a slender, pointed head. Its eyed side is an olive to dark brown or almost black in some cases and the blind side is a white or creamy white color. This species has unpaired fins ranging from a white to yellow-orange complexion, with black bands running perpendicular to the fish. The posterior fin or caudal fin is slightly rounded. Lateral lines with a slight curve run over the
pectoral fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...
and a complete lack of an accessory dorsal branch is found within this species. This species relies heavily on its strong anal spine for swimming.
This anal spine is used as the primary driver of locomotion while the fish is swimming through the open ocean. Through an up and down motion the fish achieves a propelling effect.
Behavior and life history
Behavior
The starry flounder has a multitude of well studied behaviors that are exhibited on a daily basis. At a normal resting position the dorsal and anal fins are angled so to prevent the body from resting upon the substrate, support being given by the fins, so as to create a cushion of water between the fish and the substrate. This is also for water to escape through an opening on the blind side, gill slit, of the fish and lessens the amount of effort needed to move.
Movement of this fish has been described to look much like crawling, with the first few rays of the
dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal co ...
and anal fins moving in a rowing motion that progresses caudally along the fish creating a waving movement of the fins, propelling the fish forward.
Flounder
Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuaries.
Taxonomy
The name "flounder" is used for several only distantly related species, thou ...
s are also capable of backwards locomotion, which is achieved with the same waving movement of the fins but the rowing motion progresses anteriorly. This movement is used as a method of escape or if it encounters an obstacle.
When quick movements are needed from this fish, such as when feeding or frightened, the pectoral fin is extended at a right angle from the body, and used as an additional paddle.
Another key behavioral ability displayed by the ''P. stellatus'' is its ability to change its body coloration depending upon the substrate or environment that it is in. This process is done by changing pigment granule concentration in
chromatophore
Chromatophores are cells that produce color, of which many types are Biological pigment, pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and ...
s, which will the result in the shade variations seen within this species.
Ecology
The primary habitat for this species is within mud, sand, or gravel bottoms from 0–375 m (1230 ft), but most commonly above 146 m (479 ft). They are usually found near shore and often enter brackish or even fresh water on occasion.
Highly salinated water is something this fish stays away from because of its inability to keep its cells from becoming hypersalinated.
Diet
The starry flounder before metamorphosis is dependent upon
plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
ic organisms as a food source during its younger stage of life. Feeding is usually done by waiting for the prey to settle to the floor or around eye level of the flounder and then make a quick lunge at the food drawing a mouthful of water also to help pull the prey in. As the fish develops more, they are able to feed upon small
clams
Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shel ...
, some larger fish,
invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s and also worms. When the starry flounder reaches adulthood the primary stomach contents that has been found are clams.
Clam
Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two she ...
s that are too large for ingestion often have their
siphons eaten.
Distribution
The starry flounder has a relatively large home range, going from the
North Pacific Ocean
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography.
Etymology
The word ''north'' is ...
all the way to Southern California. Within the Pacific Ocean they are located in Korea and Southern Japan through Bering Strait and Arctic Alaska to the
Coronation Gulf
Coronation Gulf lies between Victoria Island and mainland Nunavut in Canada. To the northwest it connects with Dolphin and Union Strait and thence the Beaufort Sea and Arctic Ocean; to the northeast it connects with Dease Strait and thence Queen M ...
. They have also been prominently found in
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
,
Santa Barbara and Southern California.
Interactions with humans
Commercial Fishing
In California the ''P. stellatus'' is of relatively minor importance within fisheries, only entering commercial catch at major fishing ports north of Point Conception. Usually filleted and often sold under the name of "sole." Not considered a very flavorful or texturely decent fish. The young and smaller individuals are more sought after than the larger and heavier fish. Within the
Bering Sea
The Bering Sea (, ; rus, Бе́рингово мо́ре, r=Béringovo móre) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasses on Earth: Eurasia and The Ameri ...
it's caught and mainly canned as a high class export item.
References
{{Taxonbar, from=Q166833
Platichthys
Fish of Japan
Fish of East Asia
Fish of North America
Fish of the Western United States
Fish described in 1787