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<br />37.5 ~ 0.5 Vim and in a descending floW 51.9 I 1.3 Vim. In the porgy it is
<br />35.2 t 0.9 and 49.4 t 0.5 Vim respectively. As With the threshold of the first
<br />reaction (Balayevand Fursa, 1980), the values of the tetanus threshold depend
<br />on the direction of the flow,but the nature of the manifestation of tetanus is
<br />the same and does not deoend on the orientation of the fish.
<br />
<br />RESEARCH RESULTS
<br />
<br />,
<br />,
<br />
<br />All previous researchers have studied the anode reaction. The history of the
<br />question, the different hypotheses and the attempt to explain its nature have been
<br />described in sufficient detail in many general works (Scheminskyet aL, 1941;
<br />Dentser, 1957; Nusenbaum and Faleyeva,196l; Sternin et aI., 1972; Danyulite,
<br />1974, etc.). However the .question as to what orientation reaction should be con-
<br />sidered the anode reaction', is to date differently interpreted by different authors.
<br />Frequently the entire gamut of the orientations of fish towards the anode is con-
<br />sidered part of the anode reaction: from the turning of the fish towards the
<br />anode at the moment of switching On the current to the headlong movement towards
<br />and remaining near it throughout the time of current action.
<br />
<br />Detailed investigation of this specific behavior of fish with the characteris-
<br />tics of the individual phases of its manifestation was carried out by Fokin and
<br />Petushko (1964). The authors distinguish 3 types of anode reaction: (1) with
<br />10 - 20 changes in current polarity the fish turn towards the anote: (2) with
<br />10 - 20 changes the . fish reach the anode but ~o not stay near it; (3) in all
<br />cases the fish reach the anode and st"y there.. We fully agree with the opinion
<br />of these authors that in m[:k;t cases.it is not the anode reaction as a directed ..
<br />movement towards the anode that is of interest, but the reaching of the anode by
<br />the nshand the fact that they stay there ,"since the directed movement towards
<br />the anode' (without reaching it) Occurs even at minimum voltage gradients 0.02
<br />VIes, while in order to reach the anode, a voltage gradient of 0.15 V/~m is re-
<br />quired, and in order to keep the fish near the anode a voltage gradient of 0.24
<br />V/= or more" (FoHn .,andPetushkci, 1964; pp~, 54-55). As we can see the differ-
<br />ence is very substantial and necessitates clear definition of the term.
<br />
<br />In all our investigations we have considered as the anode reactions the re-
<br />action of fish characterized by these authors as "anode reaction 3" (see Methods
<br />section). Following.other authors (Nusenbauin and Faleyeva,.l96l, etc.) ,we
<br />called aU the remaining approximate reactions the "anode flexure" and "anode
<br />turn." According to 'this, fish which did not stay riear the anode whatever the
<br />current values, are placed in the group of fish w,ith.no anode reaction.
<br />
<br />There are also indications of a cathode reaction witli or1.entatioll towards
<br />the cathode, and also to more complex behavior than the simple classical anode.
<br />reaction, when turning towards, the anode (Ewald, 1894; . Delov ,and. ToDlBshevskiy,
<br />1.933; Blancheteauet aI., 1961; Lamarque, 1963; Vibert,1963,' etc.).'. However,.
<br />in iovestigations.devotedspecially to verifying these data (Danyulite .and
<br />Kalyukina,:,196 7; :Petr~uskene,. 1-'76) ,;no.such'pattern .was obser"ed, ,
<br />
<br />Asa result of'anatoinic' investigation of thestructu.reot the nervous system
<br />of 2 species of fish, Grinberg (1967) c,onc1uded that the French investigators had
<br />approached the solution. of the question of the behavior of fish :l.nelectric fields
<br />100 schematically. Dentser (1957) had already' considered the case afthe cathode
<br />reaction as an exception, requiring scientific explanation. He pointed out that
<br />iD this case we may possibly be dealing not with a cathode reaction, but with a
<br />reaction connected with great current density. If the fish were oriented towards
<br />the cathode at the moment of -switching on the current Danyulite (1961) note.d -an
<br />initial sharp darttowardsit,and therta turn and a movement towards the anode.
<br />In SOlIe. cases the fish did not succeed.in turning towards the anode and 'were
<br />'narcotized in the original position or reached the anode on the side. Similar
<br />cases were not infrequently observed also in our experiments. At the moment the
<br />current was switched on,the fish made a dash in the directicm inwhich it was
<br />
<br />
<br />138
<br />
<br />
<br />
<br />time and afterwards it turned towards the anode. If the fiel~
<br />pointing at the ~lose to the tetanus threshold, the fish were sometimes un
<br />intencity was high, f tr g spasms of the body muscles and
<br />able to turn towards the anode b~ca~~: ~at~od~nbY means of uncoordinated body
<br />at times were able to move towar s i bilized frequently with an anode flexure.
<br />flextures, as long as they wereh~ot i:m~ommon with a directed position-finding re-
<br />Naturally such movement had not 1ng t'me a distinctly expressed cathode re-
<br />
<br />action in anf eledcitnrimCanfiye~~~er~:b~:~e:a7~hi~lauSkayte and Danyulite, 1972; Shid-
<br />action was oun
<br />lauskayte, 1973).
<br />
<br />. .we ex lain the behavior of the fish observed by
<br />
<br />us? B~:r~~g k~:~ ;~ar;r~~ff:~:n~a:::~i;~:~~c:::~r:r:n:h:::;:s:;:i:::":;:: (':::::;,
<br />
<br />ical reaction stereotypes as reg b ki divided the fish into 2 large groups ac-
<br />1959; Rekubratskiy, 1967~. ~e~ ~at~ ~l) those actively fleeing from danger
<br />cording to typ~ of defens1ve w: ~fo~ife) and (2) those with clearly expressed
<br />(mainly fish w1th a school~d y mainl fish living in the coastal zone and
<br />concealment in dangerous s1tuati:~:e~n the~e 2 extreme types, there are transitional
<br />with a solitary way of life). B d 1 ic 1 features of behavior corresponds
<br />forms. Such a description as regar s.ec~h~;e :ith or without anode reaction and
<br />to our division of fish into ~ g~~~i~~ fish, mainly pelagic species, belong to the
<br />an int.ermediate group. Activ, d d . s 1 fish belong to the second. Let
<br />F irl~ immobile bottom an emer a .
<br />first group. a J . f f their response reactions to the act10n
<br />us consider the distinguish1ng eatures 0
<br />of an electric current.
<br />
<br />stimulus provoking a defence reaction
<br />An electric current serves a~ a strong . 'i the form of flight. Since
<br />in fish. Inactive, mobile fish this react10n o~~~:s t~e flight of active fish
<br />all fish prefer the desce~ding to the adscend~nga rul~ it is violent, and sometimes
<br />also occurs in the direct10n of the ano e. s
<br />the fish jump out of the aquarium.
<br />
<br />'e attempt at any sign of danger, to find a
<br />Fairly inactive, stationary spec1 S i to'a current is similar. Consequently
<br />d hid Their response react on h
<br />refuge an to e. . he bream and the reef-fish.move about t e
<br />even such freely~sw1mmingfishes ~sdt t remain near the anode, although they
<br />aquarium in search of a refuge an 0 no ed in the more peaceful swimming
<br />distinguish the polarity of the cur~ent, ~~~::s~onvince us that this is in fact
<br />towards the anode. The fOllOW~ng o.~e~va ) investigated by us, the response
<br />so. In 3 specimens of wrasse cr~n~ a rus tSP'as defense behavior typical of them:
<br />reaction to the switching on of t e curr~n 'I: on the bottom on their side. This
<br />after the current had been switched on t eYtiOY a higher voltage was required. The
<br />was not tetanus, because for 8 tetanus reac .n field tension by an anode reac-
<br />shore rocklin~; which usually resioln~~ t~cas~~::~ra bush or bits of debris matter)
<br />tion would, when a refuge was ava a e y
<br />
<br />hide in it.
<br />
<br />. b h . r of fish of different spe-
<br />Dentser (1957) gives facts on the varY1ng e a~10ing the action ofa current,
<br />cies.during electric fishing.' Thus f~r inst~nce~ndu~urrows into the silt, leaving
<br />
<br />the tench, Tinaatinca, Plu~~es;iAt~hr::i w~s~~re and agressiveness is not infre-
<br />only part of the trunk outs.. e.. i fi 1/ Bream attack each other. Thethreat
<br />quently noted .in fish in an el~ctr c ie flsh stargazer and greater weever.
<br />posture. is. characteristic of t e scorp on '.
<br />
<br />d d It scorpionfish can be explained
<br />The different behavior of the young an aUt t e is not yet consolidated
<br />by the fact that the characteristic a~~h~~;~:a~s s n~~~~n~P to prevent ,the manifesta-
<br />'in the young, they are more ,mobile ar difference in development of an electro-
<br />tion of an ,anode reaction. A simil i d adult specimens of the scorpion-
<br />defensive conditioned reflex reaction n young an
<br />fish is described by Aronov (1959).
<br />
<br />( d oby) Black Sea blenny,
<br />I'. .. . fish. which have no anode reaction roun g b b d'
<br />n some ,. . . scul in) an anode flexure may e 0 serve .
<br />scorpionfish, stargazer, shorthornhe fi~h turns in the direction of the anode
<br />after the current is switched on t 1 this is observed when the current is a
<br />with the head and tail. Most frequent y
<br />
<br />139
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