Benthic cnidarian species often dominate the community from the intertidal zone to the deep seafloor. They feed through ingestion of suspended particles and small planktonic organisms. Furthermore, they can ingest animals many times larger than their size, in a solitary action referred to as protocooperation with many polyps simultaneously engaged in the capture. The aim of this PhD thesis was to evaluate to what extent these organisms benefit from aggregations large prey exploitation and, when the capture is shared among many polyps, what are the costs and advantages of cooperation over intra-specific competition. The field observations and literature review highlighted that large prey are most represented by large gelatinous plankton, generally considered as trophic endpoints. Their capture requires a particular feeding behaviour, that fits the term “macro-predation”, opposite to “micro-predation”. This neglected trophic relationship could play an important role in bentho-pelagic coupling and in the nutrient cycle of benthic systems. Laboratory experiments on Aurelia coerulea polyps showed an improvement of the fitness and a trend to decrease the interindividual distances to perform protocooperative predation. Polyps can detect the prey-produced molecules and to behave accordingly, mimicking the necessary behaviour to capture the large prey. This observation indicated the involvement of learning processes and memory acquisition. Cnidaria represents an intriguing phylum that is often considered the precursor of many biological and physiological processes that later evolved in Bilateria. The protocooperative interactions among individuals, even though not mediated by cognition, and the derived benefits of large prey feeding, could represent the baseline from which sociality evolved in metazoans, leading to highly coordinated societies that characterize many vertebrate and invertebrate taxa.
Le comunità bentoniche sono abitate da polipi bentonici appartenenti al phylum Cnidaria, che si nutrono di particelle in sospensione e piccoli organismi planctonici. Sono inoltre voraci predatori di organismi di notevoli dimensioni, catturati tramite un’azione protocooperativa: molti polipi agiscono contemporaneamente, condividendo lo sforzo predatorio ed i benefici che ne derivano. L’obiettivo di questa tesi è valutare in che misura i polipi approfittano dalla loro vicinanza per catturare una preda di grandi dimensioni, e quali sono i costi e i vantaggi della cooperazione rispetto alla competizione intraspecifica. Le osservazioni in ambiente marino e la revisione della letteratura hanno evidenziato che gli organismi maggiormente predati appartengono al plancton gelatinoso, generalmente considerato “endpoint” della rete trofica. La loro predazione richiede un particolare comportamento alimentare, meglio descritto con il termine “macro-predazione”. Questa relazione trofica, ad oggi trascurata, può svolgere un ruolo importante nel “coupling” bento-pelagico e nel ciclo dei nutrienti dei sistemi bentonici. Gli esperimenti di laboratorio hanno dimostrato un miglioramento della fitness dei polipi di Aurelia coerulea, ed una tendenza a diminuire le distanze interindividuali in seguito a protocooperazione. Quest’ultima può essere innescata dal rilevamento di molecole prodotte dalla preda (segnali chimici), inducendo i polipi ad ad imitare il comportamento precedentemente attuato per la sua cattura. Questa osservazione indica il coinvolgimento di processi di apprendimento in seguito a precisa stimolazione. Il phylum Cnidaria è considerato precursore di molti processi fisiologici e biologici successivamente evoluti nei Bilateria. Le interazioni protocooperative tra individui e i benefici da esse derivanti potrebbero rappresentare il punto d’avvio da cui si è sviluppata la socialità nei metazoi, portando alle società altamente organizzate che caratterizzano molti taxa animali.
The Value of Neighbourhood: Collective predation upon large prey by benthic Cnidaria and its influence on individual predator behaviour, group fitness and population dynamics / Gregorin, Chiara. - (2024 Jun 05).
The Value of Neighbourhood: Collective predation upon large prey by benthic Cnidaria and its influence on individual predator behaviour, group fitness and population dynamics
GREGORIN, CHIARA
2024-06-05
Abstract
Benthic cnidarian species often dominate the community from the intertidal zone to the deep seafloor. They feed through ingestion of suspended particles and small planktonic organisms. Furthermore, they can ingest animals many times larger than their size, in a solitary action referred to as protocooperation with many polyps simultaneously engaged in the capture. The aim of this PhD thesis was to evaluate to what extent these organisms benefit from aggregations large prey exploitation and, when the capture is shared among many polyps, what are the costs and advantages of cooperation over intra-specific competition. The field observations and literature review highlighted that large prey are most represented by large gelatinous plankton, generally considered as trophic endpoints. Their capture requires a particular feeding behaviour, that fits the term “macro-predation”, opposite to “micro-predation”. This neglected trophic relationship could play an important role in bentho-pelagic coupling and in the nutrient cycle of benthic systems. Laboratory experiments on Aurelia coerulea polyps showed an improvement of the fitness and a trend to decrease the interindividual distances to perform protocooperative predation. Polyps can detect the prey-produced molecules and to behave accordingly, mimicking the necessary behaviour to capture the large prey. This observation indicated the involvement of learning processes and memory acquisition. Cnidaria represents an intriguing phylum that is often considered the precursor of many biological and physiological processes that later evolved in Bilateria. The protocooperative interactions among individuals, even though not mediated by cognition, and the derived benefits of large prey feeding, could represent the baseline from which sociality evolved in metazoans, leading to highly coordinated societies that characterize many vertebrate and invertebrate taxa.File | Dimensione | Formato | |
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