Doctor fish

Those Doctor fish (Acanthuridae), also Segelbader or Surgeon fish called, form one in that that Doctor-fish-well-behaved, the three and 72 covers. Among the next the related doctor fish probably rank those Diana fish and Rabbit fish.

The designation of doctor fish is derived from the "skalpellen" or horn-like blade, which can carry these fish before the tail root and use them as defensive weapon. The scientific name goes on the 1787 for the first time described type kind Acanthurus ( ??????????, "the Dornenschwaenzige") back, their designation for its part from the Greek one ??????, ácantha, "the prick" and ????, ourá, "the tail" is compound. The family became 1810 by the French Naturalisten Constantine Rafinesque established.

Spreading

Doctor fish exclusively live in and have one zirkumtropische Spreading, are thus world-wide in waters. Five kinds live in Atlantic, the remaining in and . The representatives of the family are in and in , , , and .

Appearance

Appearance

Most doctor fish types reach a body length of 30 to 40 centimeters. Among the dwarves in this family rank that Japanese doctor fish (Acanthurus japonicus) and Edge universe doctor fish (Acanthurus randalli), which reach only in each case one body length of up to 18 centimeters, as well as smallest kind that Tomini Borstenzahndoktorfisch (Ctenochaetus tominiensis), which becomes only 12 centimeters long.

The giants in this family are kinds that . That Long nose doctor fish (Naso annulatus) a body length of up to 1 meter, that reaches Horse head nose doctor fish (Naso fangeni) becomes centimeters long up to 80. For nose doctor fish the horn-like Auswuelstungen on the forehead is typical and also named-giving - they can become in such a manner large with some kinds that attained full growth fish are not any more able, of being able to abzupfen with their muzzle algae of korallen or of the underground. It comes therefore to a food conversion of algae to plankton.

For doctor fish the hochrueckigen and very narrow bodies are typical. With the Unterfamilie of the nose doctor fish the body is generally somewhat longer and works thereby more spindelfoermiger. A difference between the sexes concerning the body colouring does not exist with doctor fish usually - however males can become larger than female, and their colouring can be somewhat more intensive during the Laichphase. With the males of the nose doctor fish the nasenfoermige Ausstuelpung on the forehead becomes frequently stronger and longer. With older males that Genuine doctor fish a front dent in such a way specified in addition can occur.

The deeply lying and very small muzzle is too own to all doctor fish, with which the Oberkiefer is somewhat longer than the lower jaw. It finalconstantly sits at the head, which constitutes a portion of approximately 15 per cent of the body length. Due to food specialization some kinds trained specific dentures forms. Like that is with that Sail fin doctor fish from the Unterfamilie that the lip somewhat extends, so that they can reach also algae in less accessible places. With that Bristle tooth doctor fish from the same Unterfamilie against it the muzzle is rather broad, and they have mobile Raspelzaehne, in order to know veralgte places abraspeln.

Some kinds change their body colouring during growing up. That Blue doctor fish (Acanthurus cerulus) is colored during his juvenilen lifetime yellow, resembles signaled thereby a fish type living in reef columns and by these its Fressfeinden that it represents only a little which is worth booty. While this phase defend the animals their district decided opposite Fresskonkurrenten, even if these kind comrades are. If their small district offers no longer sufficiently food to them, they accept the colouring of the adults of animals and form then together with kind comrade Fressschwaerme. The blue doctor fish a comparable mimicry show also that Circle thorn doctor fish (Acanthurus tennenti) and that Chocolate doctor fish (Acanthurus pyroferus). They resemble as young fish that Dwarf emperor fish, which are likewise only very heavy to erjagende reef column inhabitants.

Moving and anal fin can during of the Impressing behavior flag-like by the body to be spread. With exception of the nose doctor fish doctor fish types have long, narrow brustflossen. With the nose doctor fish the brustflossen are briefly and broadly rounded off against it.

The sheds of the doctor fish types are very small. Due to the relative sterility of the sea water have doctor fish types compared with suesswasserfischen in addition a thin skin and a thin Schleimschicht.

The skalpelle

Doctor fish have to twenty sharp "skalpelle" or thorn extensions at the tail root, with which they can defend themselves. The "skalpelle" developed from the transformation of a segment and have razor-sharp planes of section. With nose and sawing doctor fish there is thorn-like horn plates, by which at least two per body side are trained.

They are frequently coloured emphasized and therefore easily to recognize. With the actual doctor fish (Acanthurinae) the skalpell is mobile and in a state of rest to the body put on. Since the "skalpelle" do not stand with muscles in connection, but only with chords at that , can the genuine doctor fish them are embodied for defense set up not actively. Instead they are put up in each case passively by tail impacts at (concave) the side of the tail handle in an angle of approximately 80 degrees, bent outward.

With the nose doctor fish the skalpelle are being certain, i.e. their blade are always operational. In each case two blade on each side of the tail root have the predominant number of nose doctor fish. Those against it three to ten knoecherne extensions both sides their tail roots possess.

The skalpelle become the defense approximately against Fressfeinde how , Zackenbar and Barracudas, in addition, with innerartlichen arguments assigned. In former times it was accepted that doctor fish with the skalpell slit the bellies of other fish types, in order to eat their entrails. That is not applicable - the skalpelle are a pure defensive weapon of the fish.

With injuries by these skalpelle it comes to symptoms of intoxication. The technical book author André Luty points thereupon that with test series also Prionorus scalpus the fish all hurt by the skalpellen died, although the skalpelle neither still glands exhibit. This is to be attributed probably to the fact that on the fischhaut protein connections present penetrate poison effect into the wounds, there to infections lead or possess as proteins.

Other kinds as for example that Pallet doctor fish (Paracantharus hepatus) or some kinds that also giftdruesen possess. With humans injuries can accompany by the pricks of the fins or by the skalpelle with the strong and painful swelling of the member masses concerned. The pain can continue thereby over weeks.

Nutrition

That Gold spot doctor fish needed in the winter as food, in order to be reproductionable

Doctor fish are food specialists, whereby itself the predominant number of the kinds after their larva phase, in that it above all animal , to a vegetable food change over. The vegetable food exists either out Algae or out ). In addition many kinds that predominantly of algae of living doctor fish take up Korallensand, in order to be able to process the cell walls of their vegetable food better. With doctor fish types, to , one in addition specific micro organisms live found, as in the digestive tract and with kinds of other fish families do not occur.

Most kinds use exclusively few certain sources of food. The Japanese doctor fish for example eats only the thread alga buildup occurring as fine Algenflaum on natural reef rock. Edge universe doctor fish needs against it a high portion of lime algae in its nutrition. With Gold spot doctor fish (Acanthurus nigrofuscus) the preferential source of food is subject to seasonal influences. In the summer it eats and . If the gruenalgen are not to it in the winter at the disposal, this effect has on its Laichfaehigkeit. Due to the consumption of gruenalgen it comes to the change that Fatty acid composition the doctor fish fats. This uses the gold spot doctor fish during the training of its gonads (gonad).

Some few kinds remain after its larva phase Planktonfresser - in addition count for example that Pallet doctor fish (Acantharus hepatus) and that Monk doctor fish (Acanthurus gahm). From the nose doctor fish types change themselves over some during their life from the Abfressen from algae again to plan acct food, because they can abfressen with attained full growth horn no more algae from the substrate. Thus they become with increasing age Planktonfressern, which satisfy their need of algae from between the plankton swimming the algae and by the food of food organisms such as Quallen, the micro algae in the form of Zooxanthellen to accommodate can.

Behavior

The 72 kinds of the doctor fish exhibit a very large spectrum at different behavior patterns, which arise partly also within a kind and are dependent on the respective environmental condition with it on the age, on the reproduction phase and. With some doctor fish types it was observed that they behave strictly territorially, if the area remains below a certain individual density. If the frequency of the kind increases against it, they train Fressschwaerme. Most frequently doctor fish are to be observed however as a single animal or as pair and behave predominantly territorially.

Swarms

In the swarm doctor fish are to be observed either during the Laichzeit or them belong to the kinds, which form Fressschwaerme.

Favourably the training of Fressschwaermen, if the fish can make themselves food reasons accessible in this way, from those is it as an individual fish of food competitors as for instance Riffbar were driven out. This applies for example to that Blue doctor fish (Acanthurus coeruleus) or that Weisskehl Doktorfisch (Acanthurus leucosternon). Against it sufficiently if food is to the fish at the disposal, the fish do not form Fressschwaerme. Thus was omitted for example with Convict doctor fish (Acanthurus triostegus), its Fressschwaerme with that up to 1.000 fish to cover know, during the Korallensterbens at these coasts in the year 1998 the clustering, because due to strong alga growth accompanying with the Korallensterben food was sufficiently present.

Also with the scientifically well examined gold spot doctor fish one stated that its behavior repertoire is strongly affected by its environmental condition. Thus became in Gulf of Eilat for individual regions stated that this doctor fish type divides its habitat into Fress and quiescent zones. At the beginning of the daily the entire population moves from up to 400 individuals of a reef section into the Fresszone, eats there common and returns in the evening to the quiescent zone, where they visit their individual sleep places. In other zones of this sea area the gold spot doctor fish forms against it only small troops of 10 to 20 fish, which eat in districts with a diameter of 10 to 20 meters and rest. Only during the Laichphase the populations in these regions form larger swarms.

Territorial behavior

Many doctor fish types behave already during their young fish time territorially and form during this time of mini districts, which defend them against Fresskonkurrenten decided. This behavior is necessary, since the young fish cannot dare themselves due to the endangerment by Fressfeinde yet in the open reef and so that them the available the algae are limited. The fish defend therefore also opposite kind comrades a district approximately around their Unterschlupf, which offers sufficiently food basis to them.

Haremsreviere

Arab doctor fish and Blue strip doctor fish (Acanthurus lineatus) one has the training of observes. The female fish controlled and defend own small districts, an individual male several of these districts. It through-swum its territory hunted on always same courses and thereby both competitive kind comrades and other plants corrosive fish.

Reproduction

Laichphase

All doctor fish types visit the free water to the Ablaichen. They are particularly endangered thereby by Fressfeinde. If the individual density is high according to within an area, they train therefore swarms, in which the individual fish is protected from these better. If the individual density is small against it, the fish laichen off also as pair. The synchronisation of the Laichverhaltens takes place thereby over mondphasen. Many kinds laichen with full moon off, with the highest accompanies. The larvae are removed by these tides far from the reef. Also this is a behavior adjustment opposite Fressfeinden, since many other reef inhabitants would eat the larvae.

Under the doctor fish types there is some, with those the female monthly is, while with other kinds seasonal Laichzyklen is to be observed. These differences can occur even within a kind as adjustment to the respective habitat. So are for example the females of the Convict doctor fish (Acanthurus triostegus) in warm waters in all year round laichbereit, while they laichen before the coasts of Hawaii only between Decembers and July.

The actual Laichakt usually begins with a Imponiergehabe, with which moving and anal fins are set up. Males and females swim thereby parallel. As usually is the case for many fish types, which ablaichen in the free water, also the doctor fish types for the actual Laichakt swim depending upon kind two to three meters upward and encounter the highest point at the same time eggs and off. Occasionally they break through thereby even the water surface. If the Laichakt happens within a larger swarm, there is thereby always individual groups, which at the same time do this and afterwards to the relative security of the swarm return.

For a number of the doctor fish types color changes of the body colouring were described during the reproduction time. Dies reicht vom heller werdenden Gesichtsfleck beim Weißkehl-Doktorfisch (Acanthurus leucosternon) und beim Japanischen Doktorfisch bis zu deutlichen Farbveränderungen beim Indischen Segelflossendoktor (Zebrasoma desjardinii), with which the contrasts of the bright and dark head restraint tire and with the schwanzflossen a blue colouring become stronger to then show. One of the most remarkable color changes shows that Mask nose doctor fish: While the grundfaerbung is to olive brown usually centralbrown, the dark-blue design on the body can change to a spectacularly shining and irisierenden blue with the balzenden male.

Development of the larvae

The females of the doctor fish types put a very high number of eggs. With a convict doctor fish female with a body length of only somewhat more than 12 centimeters the number of abgelaichten eggs was 40.000. These eggs have an oil ball, due to which they can float freely in the water.

The period, which passes between Ablaichen and larva slip, is not only kind -, but also water temperature-dependently. With the convict doctor fish larvae slip with a water temperature of 24 °C already 26 hours after the Laichakt. These larvae live first on their Dottersack and eat for the first time after five to six days. They nourish themselves thereby of in the plankton along-floating small cancers and young fish:

The larvae turn after approx.. 2 - 2.5 months to the reef lagoons and Mangrovenwaeldern the coasts back, where they find sufficiently food and hiding places. Those Acronurus [ larvae ] are disk-shaped, transparency and shedless, have however a shining abdomen and long time than own fish type were described.... The transformation of Acronurus to the small Acanthurus carries out itself within 5 days. If the larvae in darkness are held, they are not converted. Only after that Metamorphosis form buildup and thread algae the main food. (Luty, S. 36)

Master history

The phylogenetische classification of the doctor fish is not yet completely clarified. After the up-to-date knowledge conditions they form only for a kind together with from existing family that Halfterfi (Zanclidae) that the Acanthuroidea. This again places the group of sisters of the Luvaroidea with that Diana fish (Luvaridae) and the Kushlukiidae? . Close relatives further are those Rabbit fish (Siganidae), those Argusfi (Scatophagidae) and those Bat fish (Ephippidae). A hypothesis to the exact verwandtschaftsverhaeltnissen is represented in the following diagram:

Acanthuroidei sensu lato
???Squamipinnata
? ???Bat fish (Ephippidae)
? ???Argusfi (Scatophagidae)
?
???Acanthuroidei sensu stricto
   ???Rabbit fish (Siganidae)
   ???N. N.
      ???Luvaroidea
      ? ??? ?Kushlukiidae
      ? ???Diana fish (Luvaridae)
      ?
      ???Acanthuroidea
         ???Halfterfi (Zanclidae)
         ???Doktorfische (Acanthuridae)

Fossil findings

The doctor fish are at the latest from the earth-history period of the admits, which began approximately 55 million years ago. The most important find place is the northItalian developed. It made the description possible more numerously fossil doctor fish from this time, among them about Acanthuroides, Gazolaichthys, Mataspisurus, Metacanthus, Pesciarichthys, Protozebransoma, Tauichthys or Tylerichthys.

Kinds admitted out the the same formation Proacanthurus and Sorbinithurus, latter about 52 million years old, can the modern Unterfamilien be probably already assigned Proacanthurus that (Acanthurinae) and Sorbinithurus that (Nasinae).

Into latter group probably also the kind falls Arambourgthurus, temporally from the early approximately 34 million years ago originates and from the Iranian Ishtebanat formation admits is, which is likewise a Relikt of the Tethyssee. From that is the kind Marosichthys admits; it became from the Indonesian island Celebes described and the occurrence of the family in the western Pacific proves. Together with Sorbinithurus and Arambourgthurus she probably imagines Taxon, its group of sisters of the modern nose doctor fish and the fossil kind Eonaso one forms. The latter became from that described; their age is indefinite, the first occurrence falls however probably at the earliest in the oligozaen and points the existence out of an westAtlantic line of development.

The above masterhistorical classification of the fossils can be inferred to the following diagram:

Doctor fish (Acanthuridae)
???diverse fossil Taxa (?Acanthuroides, ...,†Tylerichthys, classification unclearly)
???Nasendoktorfische (Nasinae)
? ???N. N.
? ? ????Marosichthys
? ? ???N. N.  
? ? ????Sorbinithurus
? ? ????Arambourgthurus
? ?
? ???N. N.
? ????Eonaso
? ???Moderne nose doctor fish (Naso)
?
???Skalpelldoktorfische (Acanthurinae)
   ???Saegedoktorfische (Prionurus)
   ???N. N.
      ????Proacanthurus
      ???Moderne Skalpelldoktorfi (Zebrasomini+Acanthurini)

Systematics

In internal systematics skalpell generally becomes -, nose and sawing doctor fish as Unterfamilien treats. The latters represent a kind, which within Skalpelldoktorfi is to be settled.

Doctor fish (Acanthuridae)
??? (Nasinae)
??? (Acanthurinae)
   ??? (Prionurus)
   ???N.N.
      ???Zebrasomini
      ? ???Pallet doctor fish (Paracanthurus)
      ? ???Sail fin doctor fish (Zebrastoma)
      ???Acanthurini
         ???Genuine doctor fish (Acanthurus)
         ???Bristle tooth doctor fish (Ctenochaetus)

Humans and doctor fish

Attitude in aquariums

Doctor fish are very fastidious as aquarium fish. Their kind-fair attitude employs high requirements . As well as this is appropriate for its pronounced on the one hand at an aggressive behavior in relation to kind comrades and other fish types, swim-rubbed the high requirements to the water quality in the aquarium. In addition a specific food need comes with many kinds.

With all copies offered in the trade it concerns beyond that game catches. The way catch of individuals from their natural districts is to be regarded generally as problematic. In addition it comes that in particular older game catches get accustomed only very heavily to a life in the aquarium, since the number of micro organisms is very much higher here than in the sea. These fish do not have a very high chance of survival in the aquarium and to get sick due to the load by the micro organisms fast.

Doctor fish are susceptible in the aquarium opposite intestine parasites. This Parasite spread in the aquarium rapidly under the cognate fish, as previously mentioned to the Kotfressern ( 13 doctor fish types and forwards 6 kinds befischt. In addition doctor fish contain a large quantity of several times insatiated n-3. They are thereby potenzielle suppliers from raw materials to the production of heart cycle preparations.

As alga-corrosive fish they take by consumption of however occasionally also the fat-soluble and heat-stable poison Ciguatoxin up and show this also to their Fressfeinde. This poison does not harm the fish - humans react to it however sensitively and can on Ciguatera die.

Literature

• André Luty: Doctor fish - way of life - care - kinds, Daehne publishing house Ettlingen, 1999, ISBN 3-921684-61-7
• Andreas Vilcinskas: Sea animals of the Tropics, Franckh cosmos publishing house Stuttgart, 2.000, ISBN 3-440-07943-0
• Helmut Debelius + Rudie H. Kuiter: Doctor fish and their relatives, Ulmer publishing house Stuttgart, 2002, ISBN 3-8001-3669-4
• Helmut Goethel: Color Atlas sea fauna - Red Sea, Indian ocean (Maldives), Ulmer publishing house Stuttgart, 1993, ISBN 3-8001-7266-6
• Stanislav franc: Sea fish, publishing house Werner Dausien, Hanau 1998, ISBN 3-7684-2940-7

Web on the left of

• HTTP://www.fishbase.org/Summary/FamilySummary.cfm?ID=412
• HTTP://www.sea water encyclopedia.de/de/5/0/0/liste_Doktorfische.htm
• HTTP://www.sea water encyclopedia.de/uebersichtdoktorfische.htm

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