Habitat preference and behavioural ecology of bobtail squids (Sepiolidae)

• Autor(a) principal: Drerup, Christian
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/14909
• topic: Behavioural ecology; Bobtail squid; Burying behaviour; Cephalopod; Sepiola; Domínio/Área Científica::Ciências Naturais::Outras Ciências Naturais

Bobtail squids (Sepiolidae, Cephalopoda) have recently become popular in scientific studies as model organisms due to their symbiotic relationship with light producing bacteria. However, the overall knowledge on the behaviour of sepiolids is based on observations on just a few of the roughly 70 extant species and must still be considered as sparsely. As understanding their behavioural ecology is vital for establishing a good welfare when holding sepiolids in captivity, the present thesis aimed at improving the knowledge on the ecology of these cephalopods. In a first study, several behavioural aspects of the so far less-investigated bobtail squid species Sepiola parva were analysed, showing that the behavioural ecology of this sepiolid greatly resembled the observations reported for other bobtail squids. Furthermore, this study did not only present the first detailed information for sepiolids about activity and time budgets as well as the positioning towards the prey and the tentacle speed during hunting events; it also provided the first evidence for the ability to adhere a ‘sand coat’ in the genus Sepiola and the use of ‘ink ropes’ for sepiolids in general. In a subsequent study, the burying behaviour of Sepiola sp. was analysed with regards to the effect of different sediment types. It was shown that the mean grain size played a major role in both the duration and the number of body movements (funnel jets/ arm sweeps) in different burying characteristics. While the latency until the start of burying, the duration and number of funnel jets of phase 1 and the total burying duration was the shortest/lowest on medium grained sediment samples and correspondingly extended on finer and coarser sediment samples, the duration of phase 2 and the number of arm sweeps within phase 2 was the longest/highest on coarser sediment and decreased the finer the sediment was.