“Flatfish”的意思、由来-开放百科全书

A flatfish is a member of the order Pleuronectiformes of ray-finned demersal fishes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through or around the head during development. Some species face their left sides upward, some face their right sides upward, and others face either side upward.

Many important food fish are in this order, including the flounders, soles, turbot, plaice, and halibut. Some flatfish can camouflage themselves on the ocean floor.

Taxonomy

Over 700 species are in the 11 families. The largest families are Bothidae, Cynoglossidae, Paralichthyidae, Pleuronectidae, and Soleidae, with more than 100 species each (the remaining families have less than 50 species each). Some families are the results of relatively recent splits. For example, the Achiridae were classified as a subfamily of Soleidae in the past, and the Samaridae were considered a subfamily of the Pleuronectidae.^[3]^[4] The families Paralichthodidae, Poecilopsettidae, and Rhombosoleidae were also traditionally treated as subfamilies of Pleuronectidae, but are now recognised as families in their own right.^[4]^[1]^[2]

The taxonomy of some groups is in need of a review, as the last monograph covering the entire order was John Roxborough Norman's Monograph of the Flatfishes published in 1934. New species are described with some regularity and undescribed species likely remain.^[3]

Hybrids

Distribution

Flatfishes are found in oceans worldwide, ranging from the Arctic, through the tropics, to Antarctica. Most species are found in depths between 0 and {{convert|500|m|ft|abbr=on}}, but a few have been recorded from depths in excess of {{convert|1500|m|ft|abbr=on}}. None have been confirmed from the abyssal or hadal zones. An observation of a flatfish from the Bathyscaphe Trieste at the bottom of the Mariana Trench at a depth of almost {{convert|11|km|ft|abbr=on}} has been questioned by fish experts, and recent authorities do not recognize it as valid.^[7] Among the deepwater species, Symphurus thermophilus lives in congregating around "ponds" of sulphur at hydrothermal vents on the seafloor. No other flatfish is known from hydrothermal vents.^[8] Many species will enter brackish or fresh water, and a smaller number of soles (families Achiridae and Soleidae) and tonguefish (Cynoglossidae) are entirely restricted to fresh water.^[9]^[10]^[11]

Characteristics

The most obvious characteristic of the flatfish is its asymmetry, with both eyes lying on the same side of the head in the adult fish. In some families, the eyes are usually on the right side of the body (dextral or right-eyed flatfish), and in others, they are usually on the left (sinistral or left-eyed flatfish). The primitive spiny turbots include equal numbers of right- and left-sided individuals, and are generally less asymmetrical than the other families.^[1] Other distinguishing features of the order are the presence of protrusible eyes, another adaptation to living on the seabed (benthos), and the extension of the dorsal fin onto the head.

The surface of the fish facing away from the sea floor is pigmented, often serving to camouflage the fish, but sometimes with striking coloured patterns. Some flatfishes are also able to change their pigmentation to match the background, in a manner similar to some cephalopods. The side of the body without the eyes, facing the seabed, is usually colourless or very pale.^[12]

In general, flatfishes rely on their camouflage for avoiding predators, but some have conspicuous eyespots (e.g., Microchirus ocellatus) and several small tropical species (at least Aseraggodes, Pardachirus and Zebrias) are poisonous.^[3]^[13]^[14] Juveniles of Soleichthys maculosus mimic toxic flatworms of the genus Pseudobiceros in both colours and swimming mode.^[15]^[16] Conversely, a few octopus species have been reported to mimic flatfishes in colours, shape and swimming mode.^[17]

The flounders and spiny turbots eat smaller fish, and have well-developed teeth. They sometimes seek prey in the midwater, away from the bottom, and show fewer extreme adaptations than other families. The soles, by contrast, are almost exclusively bottom-dwellers, and feed on invertebrates. They show a more extreme asymmetry, and may lack teeth on one side of the jaw.^[12]

Flatfishes range in size from Tarphops oligolepis, measuring about {{convert|4.5|cm|in|abbr=on}} in length, and weighing {{convert|2|g|oz|abbr=on}}, to the Atlantic halibut, at {{convert|2.5|m|ft|abbr=on}} and {{convert|316|kg|lb|abbr=on}}.^[12]

Species and species groups

Reproduction

Flatfishes lay eggs that hatch into larvae resembling typical, symmetrical, fish. These are initially elongated, but quickly develop into a more rounded form. The larvae typically have protective spines on the head, over the gills, and in the pelvic and pectoral fins. They also possess a swim bladder, and do not dwell on the bottom, instead dispersing from their hatching grounds as plankton.^[12]

The length of the planktonic stage varies between different types of flatfishes, but eventually they begin to metamorphose into the adult form. One of the eyes migrates across the top of the head and onto the other side of the body, leaving the fish blind on one side. The larva also loses its swim bladder and spines, and sinks to the bottom, laying its blind side on the underlying surface.

Evolution

In 2008, a 50-million-year-old fossil, Amphistium, was identified as an early relative of the flatfish and transitional fossil.^[18] In a typical modern flatfish, the head is asymmetric, with both eyes on one side of the head. In Amphistium, the transition from the typical symmetric head of a vertebrate is incomplete, with one eye placed near the top of the head.^[19] The researchers concluded, "the change happened gradually, in a way consistent with evolution via natural selection—not suddenly, as researchers once had little choice but to believe."^[18]

Flatfishes have been cited as dramatic examples of evolutionary adaptation. Richard Dawkins, in The Blind Watchmaker, explains the flatfishes' evolutionary history thus:

As food

Flatfish is considered a Whitefish^[21] because of the high concentration of oils within its liver. Its lean flesh makes for a unique flavor that differs from species to species. Methods of cooking include grilling, pan-frying, baking and deep-frying.

Timeline of genera

See also

References

1. ^¹{{Cite book | edition = 4 | publisher = John Wiley & Sons | isbn = 978-0-471-25031-9 | last = Nelson | first = J. S. | title = Fishes of the World | location = Hoboken, NJ | date = 2006}}
2. ^¹{{cite book |title=Fishes of the World |edition=5th |author1=J. S. Nelson |author2=T. C. Grande |author3=M. V. H. Wilson |year=2016 |pages=752 |publisher=Wiley |ISBN= 978-1-118-34233-6 |url=https://sites.google.com/site/fotw5th/ }}
3. ^¹²Randall, J. E. (2007). Reef and Shore Fishes of the Hawaiian Islands. {{ISBN|1-929054-03-3}}
4. ^¹Cooper, J.A.; and Chapleau, F. (1998). Monophyly and intrarelationships of the family Pleuronectidae (Pleuronectiformes), with a revised classification. Fish. Bull. 96 (4): 686–726.
5. ^¹Garrett, D.L.; Pietsch, T.W.; Utter, F.M.; and Hauser, L. (2007). The Hybrid Sole Inopsetta ischyra (Teleostei: Pleuronectiformes: Pleuronectidae): Hybrid or Biological Species? American Fisheries Society 136: 460–468
6. ^Food and Agriculture Organization of the United Nations: Platichthys flesus (Linnaeus, 1758).. Retrieved 18 May 2014
7. ^Jamieson, A.J., and Yancey, P. H. (2012). On the Validity of the Trieste Flatfish: Dispelling the Myth. The Biological Bulletin 222(3): 171-175
8. ^Munroe, T.A.; and Hashimoto, J. (2008). A new Western Pacific Tonguefish (Pleuronectiformes: Cynoglossidae): The first Pleuronectiform discovered at active Hydrothermal Vents. Zootaxa 1839: 43–59.
9. ^Duplain, R.R.; Chapleau, F; and Munroe, T.A. (2012). A New Species of Trinectes (Pleuronectiformes: Achiridae) from the Upper Río San Juan and Río Condoto, Colombia. Copeia 2012 (3): 541-546.
10. ^Kottelat, M. (1998). Fishes of the Nam Theun and Xe Bangfai basins, Laos, with diagnoses of twenty-two new species (Teleostei: Cyprinidae, Balitoridae, Cobitidae, Coiidae and Odontobutidae). Ichthyol. Explor. Freshwat. 9(1):1-128.
11. ^Monks, N. (2007). Freshwater flatfish, order Pleuronectiformes. Retrieved 18 May 2014
12. ^¹²³⁴⁵{{cite book |editor=Paxton, J.R. |editor2=Eschmeyer, W.N.|author1=Chapleau, Francois |author2=Amaoka, Kunio|year=1998|title=Encyclopedia of Fishes|publisher= Academic Press|location=San Diego|pages= xxx|isbn= 0-12-547665-5 |nopp=true}}
13. ^Elst, R. van der (1997) A Guide to the Common Sea Fishes of South Africa. {{ISBN|978-1868253944}}
14. ^Debelius, H. (1997). Mediterranean and Atlantic Fish Guide. {{ISBN|978-3925919541}}
15. ^Practical Fishkeeping (22 May 2012) Video: Tiny sole mimics a flatworm. Retrieved 17 May 2014.
16. ^Australian Museum (5 November 2010). This week in Fish: Flatworm mimic and shark teeth. Retrieved 17 May 2014.
17. ^Hanlon, R.T.; Warson, A.C.; and Barbosa, A. (2010). A “Mimic Octopus” in the Atlantic: Flatfish Mimicry and Camouflage by Macrotritopus defilippi. The Biological Bulletin 218(1): 15-24
18. ^¹{{cite news | url=http://news.nationalgeographic.com/news/2008/07/080709-evolution-fish.html | title=Odd Fish Find Contradicts Intelligent-Design Argument | publisher=National Geographic |date= July 9, 2008 | accessdate =2008-07-17}}
19. ^{{cite journal|author=Matt Friedman|title=The evolutionary origin of flatfish asymmetry| url=http://www.lacertilia.com/creationist_critiques/PDFs/Friedman_2008.pdf | journal=Nature Letters | volume=454| year=2008| pages=209–212| doi= 10.1038/nature07108| pmid=18615083|issue=7201}}
20. ^{{cite book | last = Dawkins | first = Richard | authorlink = Richard Dawkins | title = The Blind Watchmaker | publisher = Penguin Books | year = 1991 | location = London |page=92 | isbn = 0-14-014481-1}}
21. ^{{cite web|title=Flatfish BBC|url=http://www.bbc.co.uk/food/flatfish}}