Energy efficiency is inherent for autonomous robotic device. Snakes are well known for their ability to low energy consumption when swimming. However, the swimming know-how is poorly understood. Designing a snake robot inspired by snakes as a tool to find out the swimming energy efficiency crucial point will lead to the development of hyper efficient undulating locomotors. In this article, we introduce a four tendons driven continuum robot made of bio-inspired compliant vertebrae to assess the energy consumption of a planar and a spatial snake motion. The tendon-driven continuum robot constitutes the head–neck part of a locomotor snake robot. A static modeling coupled with an optimization method was implemented to generate bio-inspired motions recorded on snake swimming head. A friction model describing the friction between cables and the disks is investigated and compared to a frictionless model. The proposed prototype is equipped with exteroceptive sensors to record motion and proprioceptive sensors to measure cable forces applied at the tip of the robot. Hence, the work of the forces, thus the energy required to execute a trajectory are computed and analyzed. The energy is introduced as a key criterion to assess the swimming motion of a locomotor snake robot.

The long-term prospective multi-centre nationwide (French) observational study FRANCISCO will provide new information on perimembranous ventricular septal defect with left ventricular overload but no pulmonary hypertension in children older than 1 year. Outcomes will be compared according to treatment strategy (watchful waiting, surgical closure, or percutaneous closure) and anatomic features of the defect. The results are expected to provide additional guidance about the optimal treatment of this specific population, which is unclear at present.

The shorelines of coral islets are subject to strong anthropogenic pressure, being highly coveted for tourism. These landforms contain unique biotic assemblages but unfortunately are limited in size making them extremely vulnerable to perturbation. Robust information linking habitat structure and species requirements is urgently needed to promote and guide the conservation of these fragile areas. New Caledonia contains critical shore habitats for two species of amphibious sea snakes. One species (Laticauda laticaudata) shelters almost exclusively under mobile beach rocks, which are both easily accessible from the sea and regularly submerged at high tide. The scarcity of such specific and spatially limited habitat restricts the distribution of this species to highly localized areas. The other species (L. saintgironsi) uses a greater variety of terrestrial refuges, but has a preference for shores with abundant beach rocks. These findings offer a robust basis to promote the conservation of these crucial habitats and to justify their inclusion in marine protected areas (MPA), which in turn should benefit a wide array of other organisms also dependent on beach rocks.

It has been previously shown that two guilds of predators, the sea kraits and their prey, the anguilliform fish (predator themselves), are far more abundant and diverse than previously suspected in coral reefs of the Indo-Pacific area. Based on diet, foraging range, feeding rate, and population size of two sea krait species, we estimated the annual uptake of anguilliform fish around Signal Island, New Caledonia. We found that more than 4000 snakes live on this 15 ha islet and that they can take up to 45 000 fish (>1.3 t) per year, essentially from 10 fish species previously considered as rare. One third of these fish are captured on the reef flat, the two other thirds within a 17 km radius surrounding Signal Island. We suggest that the foraging areas of the different snake populations belonging to numerous islets (and the surrounding reef flats) overlap greatly.

Persistent patency of the arterial duct is one of the most common congenital cardiac malformations. We recently showed that mutations in the MYH11 gene result in a disease combining familial thoracic aortic aneurysm and dissection, along with patency of the arterial duct. It is also known that the smooth muscle myosin heavy chain is involved in the physiological closure of the arterial duct. With this in mind, we investigated whether the MYH11 gene was a susceptibility gene for sporadic occurrence of isolated persistent patency of the arterial duct. We sequenced the entire coding sequence of the MYH11 gene in 60 Caucasian children with persistent patency born after 36 weeks of gestation. The frequencies of rare genetic variants, and single nucleotide polymorphisms, were compared with 192 normal controls. Two possible functional missense mutations were found in two affected individuals. Another rare variant, specifically p.Arg1535Gln, and two coding polymorphisms, namely p.Ala1234Thr and p.Val1289Ala, had allele frequencies similar to those in controls. Haplotype analysis after estimating linkage disequilibrium was carried out using six polymorphisms. Individual genotypes were distributed similarly among cases and controls. Only one of the seven major haplotypes was significantly less frequent among cases, at 0.07, than among controls, when the figure was 0.22 (OR 0.23 [0.08–0.27]). Our findings suggest that the MYH11 gene is involved in only rare instances when persistent patency of the arterial duct occurs in sporadic fashion.

Amphibious animals may be subject to strong but conflicting selective pressures to enhance locomotor performance both on land and in the water. Biomechanical models suggest that in snakes, adaptations to swimming (e.g. reduction of ventral plates, flattening of tail) will reduce their ability to move on land. The locomotor speeds of six taxa of amphibious (laticaudid) sea-snakes, plus one entirely marine (hydrophiid) species were measured. Because the relative dependence on aquatic vs terrestrial habitats varies with a laticaudid's species, sex and body size, a previous study predicted that these factors should generate significant variation in locomotor speeds within laticaudids. Measurements of swimming and crawling speeds supported this prediction. Some species were faster than others and, within each species, males were faster than conspecific females. The degree of locomotor superiority of males was greater for terrestrial (>40%) than for aquatic (20%) locomotion. Smaller snakes were faster than larger animals in relative speed (body lengths/s) but slower in absolute terms (m/s). The hydrophiid Emydocephalus annulatus was slow in water as well as on land, perhaps because it eats immobile prey and thus, does not depend on speed for foraging. The diversity of locomotor abilities within laticaudid sea-snakes provides a remarkable opportunity to identify factors that influence evolutionary trade-offs between conflicting evolutionary optima.

Some organisms rely on stored energy to fuel reproductive expenditure (capital breeders) whereas others use energy gained during the reproductive bout itself (income breeders). Most species occupy intermediate positions on this continuum, but few experimental data are available on the timescale over which food intake can affect fecundity. Mark–recapture studies of free-ranging female aspic vipers Vipera aspis have suggested that reproductive output relies not only on the energy in fat bodies accumulated in previous years, but also on food intake immediately before ovulation. A simple experiment was conducted to test this hypothesis, maintaining female snakes in captivity throughout the vitellogenic period and controlling their food intake. The energy input of a female strongly influenced the amount of mass that she gained and the number of ova that she ovulated. Multiple regression showed that litter size in these snakes was affected both by maternal body condition in early spring (an indicator of foraging success over previous years) and by food intake in the spring before ovulation. Our experimental data thus reinforce the results of descriptive studies on free-ranging snakes, and emphasize the flexibility of energy allocation patterns among vipers. Reproducing female vipers may combine energy from ‘capital’ and ‘income’ to maximize their litter sizes in the face of fluctuating levels of prey abundance.

Repeated measurements of captive-born Gaboon vipers Bitis gabonica from an inbred stock examined the degree to which an animal's size and shape are affected by food intake. We also used the level of asymmetry in dorsal coloration as an index for possible genetic (inbreeding?) effects. Both of these factors, and the interaction between them, affected phenotypes of the young snakes. Snakes raised with abundant food differed from their less well-fed siblings not only in size, but also in body mass relative to snout–vent length, head length relative to snout–vent length, head width relative to head length, and fang length relative to jaw length. Hence, our data show that body proportions (including the feeding apparatus) can be influenced by the environment after birth.