Object Transportation System Mimicking the Cilia of Paramecium aurelia Making Use of the Light-Controllable Crystal Bending Behavior of a Photochromic Diarylethene

The design of an object transportation system exploiting the bending behavior of surface-assembled diarylethene crystals is reported. A photoactuated smart surface based on this system can transport polystyrene beads to a desired area depending on the direction of the incident light. Two main challenges were addressed to accomplish directional motion along a surface: first, the preparation of crystals whose bending behavior depends on the direction of incident light; second, the preparation of a film on which these photochromic crystal plates are aligned. Nuclei generation and nuclear growth engineering were achieved by using a roughness-controlled dotted microstructured substrate. This system demonstrates how to achieve a mechanical function as shown by remote-controlled motion along a surface

World squid fisheries

Peer reviewedPublisher PD

Is commercial harvesting of spawning aggregations sustainable?—The reproductive status of the squid Loligo bleekeri

As marine species that are harvested during spawning aggregation tend to be overfished, sufficient “reproductive escapement” is required to manage such overexploited populations. Because the reproductive value of short-lived organisms changes towards the end of their life span, information is required not only on the total amount harvested but also on the characteristics of the individuals caught. As spawning aggregations of the squid Loligo bleekeri are targeted by the commercial fishing industry, we analysed biological data of harvested squid to identify indicators of reproductive status. Females of this species had several sperm resources associated with alternative mating behaviours: in seminal receptacle near the mouth, around the seminal receptacle, and inside the opening of the oviduct, associated with alternative mating behaviours. However, only the mass of sperm on the oviduct was significantly related to oviduct weight (including ovulated eggs): oviduct weight was less when sperm mass was attached to the oviduct than when it was not, indicating that the female had paired with a consort male and had spawned before she was caught. Using this indicator to confirm a recent spawning event, we determined that only 22.9% of females spawned before they were harvested. Our results show that the commercial fishing industry mainly harvests squid that have not spawned and have high reproductive values. Further information on the movement and reproductive behaviour of squid is required to develop a management strategy for the coastal fishing industry that ensure sufficient reproductive escapement