Intersexual Trophic Niche Partitioning in an Ant-Eating Spider (Araneae: Zodariidae)

ants that are polymorphic in body size and hence comprise potential trophic niches for the spider, making this system well-suited to study intersexual trophic niche partitioning.Comparative analysis of trophic morphology (the chelicerae) and body size of males, females and juveniles demonstrated highly female biased SSD (Sexual Size Dimorphism) in body size, body weight, and in the size of chelicerae, the latter arising from sex-specific growth patterns in trophic morphology. In the field, female spiders actively selected ant sub-castes that were larger than the average prey size, and larger than ants captured by juveniles and males. Female fecundity was highly positively correlated with female body mass, which reflects foraging success during the adult stage. Females in laboratory experiments preferred the large ant sub-castes and displayed higher capture efficiency. In contrast, males occupied a different trophic niche and showed reduced foraging effort and reduced prey capture and feeding efficiency compared with females and juveniles.Our data indicate that female-biased dimorphism in trophic morphology and body size correlate with sex-specific reproductive strategies. We propose that intersexual trophic niche partitioning is shaped primarily by fecundity selection in females, and results from sex-differences in the route to successful reproduction where females are selected to maximize energy intake and fecundity, while males switch from foraging to invest in mating effort

HYDRA: multipurpose ship designs in engineering and education

The cornerstone of post-graduate naval architecture and marine engineering education at UCL is the Ship Design Exercise. This three-month full-time project sees students placed in small, multi-disciplinary teams and challenged with the concept design of a new vessel based on broad outline require-ments provided by the academic staff. This exercise exemplifies the use of design as an integrative teaching method, allowing engineering students to place their academic understanding of technical subjects in a whole-ship concept. This paper describes an innovative design – HYDRA – featuring a single core vessel capable of adaption during build to take on several military or civilian roles. This paper not only describes the technical aspects of the design solution itself, but also discusses the educational implications of setting students the challenge of designing ships to meet multiple, sometimes contradictory requirements. In addition to aligning well with some modern trends in ship design and construction, this type of problem is seen to offer potential benefits in engineering education. These benefits are discussed, in addition to the potential complications they bring to various aspects of the design exercise