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Title: Ecological, behavioural and biochemical studies of avoidance responses in sea-stars
Author: Mayo, Paul
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1975
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Chemoreceptive avoidance behaviour amongst sea-stars was studied. The aim was description of the active chemicals, the specificity and the ecological function of the behaviour. Extracts of the predatory sun-star, Crossaster papposus, which elicited like the live animal, the escape of the common sea-star Asterias rubens, were partly purified. The activity consisted of two, amphoteric, low-molecular weight (100 - 500 MW) substances which were fairly acid - and thermo-stable, unaffected by a proteolytic enzyme or alkali and soluble in ethanol, propan-l-ol and butan-l-ol but not in ether or chloroform. The two factors were associated with identified mixtures of amino-acids and nucleosides respectively, synthetic mixtures of which were inactive separately and together. The activity was located in the tube-feet of Crossaster and similar activity was found in the marginal spines of the closely-related Solaster endeca. The activity was measured with a semi-quantitative bioassay employing 10-20 live Asterias per sample. The response of Asterias to various live sea-stars and extracts were compared. Avoidance was elicited by Crossaster, S. endeca and Luidia ciliaris. Confirmation that these species are predators of Asterias in the field and laboratory in Europe but not in Pacific waters was provided by a questionnaire sent to marine scientists world-wide. A. survey of the distribution of A. rubens and C. papposus in the River Crouch estuary, Essex, produced only circumstantial evidence that avoidance behaviour may separate the species at a distance. The contact escape responses of Asterias to Crossaster and to Solaster and of Marthasterias to Crossaster were measured and showed a characteristic profile of velocity vs. time. Crossaster extract produced a different profile indicating a tactile element in the contact response. A new intra-specific avoidance was observed in Crossaster. Crossaster extract produced a response profile unlike the above escape reactions indicating a different function, probably in dispersal.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available