Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Smoothhound sharks Mustelus mustelus (Chondrichthyes: Triakidae) were
conditioned to associate a compound auditory and electrical conditioned stimulus (CS)
using the presentation of food as the unconditioned stimulus (US). This was done to
investigate the general conditioning process of sharks, specifically the use of conditioned
stimuli, the time frame required for conditioning, the retention of conditioned responses
and the individual learning capabilities of sharks in classical conditioning experiments.
Conditioning was done in two CS experiment replicates, in which the CS and the US
were paired to elicit a conditioned response (CR: entering of a feeding area). Shark
behaviour in these replicates was compared with those of sharks in a CS control. In the
CS control, the CS and US were not paired; consequently no CS-US association was
formed. In contrast, half of the sharks in the 1st and 2nd CS replicates formed the
conditioned CS-US association after five and six days of conditioning training,
respectively. This conditioned association was also retained over a two-month rest
period. However the rate of conditioning of sharks varied, which was thought to be due
to differences in motivational drives, particularly hunger. These experiments
demonstrated that classical conditioning could provide a mechanism whereby
smooth hound sharks can adapt to utilise new food sources.
However these experiments could not demonstrate whether auditory or electrical
cues are more biological relevant signallers of the presence of food for smooth hound
sharks. According to the "belonging ness" phenomenon, for conditioning to be
successful, the CS should be biologically relevant to the US. Therefore by comparisons
of the conditioning success with different conditioned stimuli, the biological relevance of each CS can be determined. To determine the biological relevance of each component
of the compound CS, an auditory or electrical CS was paired with the presentation of
food (US), in separate experiments. The conditioned CS-US association formed in the
majority of the sharks after 60 and 57 conditioning trials in the auditory CS and electrical
CS experiment, respectively. This suggests that both auditory and electrical cues are
biologically relevant signallers of food, facilitating the oppurtunistic feeding behaviour of
smoothhound sharks. However, after five days of conditioning, conditioning with the
electrical CS had proceeded further and the electrical CS-US association was stronger
than the auditory CS-US association. This indicates that electrical cues are more
biologically relevant due to past feeding experiences. Thus, classical conditioning during
past feeding experiences can influence the feeding behaviour of smooth hound sharks. / AFRIKAANSE OPSOMMING: Gladde-hondhaaie Muste/us muste/us (Chondrichthyes: Triakidae) is gekonditioneer
om "n gekombineerde klank en elektriese konditionerings stimulus (CS) met voedsel, die
ongekonditioneerde stimulus (US) te assosieer. Dit is gedoen om die konditionerings
proses, spesifiek die gebruik van konditionerings stimuli, tyd benodig vir konditionering,
behoud van die gekonditioneerde gedrag en individuele leer-vermoëens van haaie in
klassieke konditionerings eksperimente te ondersoek. Konditionering is gedoen in twee
CS eksperiment replikate, waarin die CS en die US saam aangebied is, om "n
konditionerings reaksie (CR: om in 'n voedings area in te beweeg) teweeg te bring. Die
gedrag van haaie in die CS replikate is vergelyk met die van haaie in "n CS kontrole. In
die CS kontrole is die CS en die US nie saam aangebied nie en gevolglik is geen
gekonditioneerde CS-US assosiasie gevorm nie. Daarenteen is die CS-US assosiasie
by die helfte van die haaie in die 1st en 2de CS replikate gevorm, na vyf en ses dae,
onderskeidelik. Hierdie gekonditioneerde CS-US assosiasie het selfs behoue gebly na 'n
twee maande rus periode. Die tempo van konditionering het egter verskil, moontlik
a. g. v. motiverings verskille, veral hongerte. Hierdie eksperimente het gedemonstreer
dat klassieke konditionering kan dien as 'n meganisme waarmee gladde-hondhaaie kan
aanpas om nuwe voedsel bronne te benut.
Hierdie eksperimente kon egter nie demonstreer óf klank stimuli óf elektriese stimuli
meer biologiese relevante seine van die teenwoordighied van voesel is vir gladdehondhaaie
nie. Volgens die "belonging ness" verskynsel, moet die CS biologies relevant
to die US wees, vir konditionering om suksesvol te wees. Dus kan die biologiese relevansie van verskillende konditionerings stimuli bepaal word deur die konditionerings
sukses van elke CS te vegelyk. Om die meer biologiese relevante komponent van die
gekombineerde CS te bepaal, is 'n klank of elektriese CS saam met voedsel aangebied
in aparte eksperimente. Die gekonditioneerse CS-US assosiasie is gevorm by die
meeste van die haaie na 60 en 57 konditionerings proeflopies in die klank en elektriese
CS eksperimente, onderskeidelik. Hierdie resultate dui daarop dat beide klank en
elektriese stimuli biologies relevante siene van voedsel is, wat die oppurtunistiese
voedings wyse van gladde-hondhaaie fasiliteer. Konditionering met die elektriese CS het
egter verder gevorder en die elektriese CS-US assosiasie was sterker as die klank CSUS
assosiasie na vyf dae van konditionering. Dus, mag elektriese stimuli meer biologies
relevant wees weens vorige voedings ervaringe. Dit illustreer dat klasseke konditionering
tydens vorige voedings ervaringe die voedings gedrag van gladde-hondhaaie kan
beinvloed.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52273 |
| Date | 04 1900 |
| Creators | Louw, Erika |
| Contributors | Cherry, M. I., Compagno, L. J. V., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 95 p. : ill. |
| Rights | Stellenbosch University |
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