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Cephalopods are fascinating marine invertebrates, known for their remarkable intelligence, complex nervous systems, and ability to rapidly change their external appearance.
Among cephalopods, I'm especially interested in the paintpot cuttlefish (Ascarosepion tullbergi), which has a strongly benthic lifestyle. It prefers slow walking on the seafloor over swimming! 😍🦑 I study the morphology, ecology, and behaviour of this unique species to understand its distinct strategy and to explore cephalopod diversity.
[How do paintpot cuttlefish walk on the sea floor?]
Most decapodiform cephalopods swim in the ocean. However, paintpot cuttlefish walks on the sea bottom by the ventral arms and the ambulatory flaps, which are erected from the ventral mantle. In this study, we examined the walking mechanism by morphological and behavioural observations. (Omura, 2020; Omura et al.,2022)
[Why can paintpot cuttlefish stay on the sea floor without slipping?]
Paintpot cuttlefish walks along the sea floor using its ventral arms and ambulatory flaps. For effective walking, certain mechanisms are required to prevent slipping in the aquatic environment. We identified the 'anti-slipping' structures involved in walking by examining the morphology of the ambulatory flaps and ventral arms, as well as observing its walking behaviour (Omura et al., 2023).
[Paintpot cuttlefish development for benthic lifestyle]
Paintpot cuttelfish has a strongly benghic lifestyle through its life. Paintpot cuttelfish's development shows a notable early investment in benthic traits, particularly arm IV and lateral edges on the ventral mantle although its development broadly aligns with other nekto-benthic cuttlefish. This early adaptation can support its continuous benthic lifestyle, in contrast to other cuttelfish that transition to different life modes as they mature. The sustained focus on benthic traits would underscore paintpot cuttelfish’s unique ecological strategy, emphasizing the role of early adaptation in maintaining a lifelong benthic niche (Omura et al., 2024).
[Functional morphology of arms and tentacles of broadclub cuttlefish]
Cuttlefish feeds mainly by using its tentacles and arms: two long tentacles are extended to catch prey, and then eight arms hold it. In this study, we are investigating how the morphology of the tentacles and arms is suitable for catching prey. (Omura and Ikeda, 2021)
[The morphology of the hectocotylus on cuttlefish]
During mating behaviour, the male cephalopod grasps a batch of spermatophores (capsules containing sperm) with a specialized arm called 'hectocotylus' and passes it to the female. However, its morphology and detailed usage are still unclear. In this study, we investigate the structure of hectocotylus, and how it is suitable for grasping spermatophore". (Omura, 2024)
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