20 science pictures to catch your eye

This bacterial spore is found, together with many of its conspecifics, in wheat straw cells in cow manure. When stored dry, it no longer forms a life-friendly environment, and some bacteria resist by going dormant and becoming spores, while waiting for more favourable conditions. Then, once the manure is rehydrated, the bacteria start breaking down organic matter again, thus helping to increase the fertility of the soil on which it is spread. Understanding the dynamics of microorganisms in soil improvers like manure is vital, and although microorganisms may be nothing like as big as a Cyclops, they nonetheless play a giant role in ecosystems.

Hyperbolic geometry, introduced in the nineteenth century, is a mathematical field that has profoundly transformed the way geometry has been taught since antiquity. In this space with unusual properties, light does not travel in a straight line but along geodesics, the shortest curves between two points, thus altering our visual perception of the world. Scientists have developed an application that simulates in real time what the “inhabitants” of such a universe would see. The image features a three-dimensional, finite volume, hyperbolic manifold, lit by a luminous globe. The ultimate goal of this project is to decipher the properties of such spaces. And to open a window onto an imaginary world sketching out the outlines of a science that can sometimes seem abstract.

A scientific diver collects a tentacle from anemones bleached by rising ocean temperatures in Moorea, French Polynesia. Warming of just a few tenths of a degree leads to the bleaching of tropical corals and sea anemones: they lose the colourful symbiotic algae that are essential for their survival. As symbionts of these marine invertebrates, clownfish are also impacted: living in a bleached anemone is stressful, and has negative impacts on fertility and physical condition. The purpose of the sampling is to identify the bacteria associated with the anemones and with the mucus of the clownfish, as well as the defence and resilience mechanisms activated in the microbiome to adapt to these changes.

This Cape fur seal has just given birth: the pink umbilical cord of her pup is still visible. She moves her baby by throwing it in the air in order to keep it away from other females in the colony, which might become very aggressive towards this little stranger if he came near them. A rather harsh, but necessary, start to life! The species forms huge, dense colonies in Namibia, where females give birth to a single pup that they nurse for 10 to 11 months. Throughout the lactation period, the young seal is exposed to long, repeated absences of its mother, who heads out to sea to feed. To be sure that their pups recognise them when they return to the noisy colony, the females wait until their offspring has fully learned to identify their voice before setting off for the first time.

Looking at the living world, its shapes, materials and structures, can inspire the materials of tomorrow. Take this cuttlefish bone, whose unique features are revealed under the microscope. Its microstructure, arranged in layers, columns and undulations, gives it remarkable properties, such as a high degree of rigidity despite very low density–with porosity of around 93%. Rather than suddenly breaking when struck, cuttlefish bone, which is made up of the calcium carbonate mineral aragonite, is instead able to absorb a large amount of mechanical energy. This damage tolerance could prove very useful in the design of future bio-inspired materials, such as ceramic foams, for the protection of people and property.

Glioblastoma is a brain tumour whose aggressive nature can be attributed to tumour stem cells. These cells, which are responsible for resistance to treatment, have the ability to form neurospheres and can enter neural differentiation pathways under certain culture conditions. Stem cells derived from human glioblastoma, clustered together in a neurosphere, can be seen in the image due to the labelling of the cell nuclei in blue. Through the action of growth factors, they adhere, migrate and differentiate, forming a ring around the initial sphere. As the cells move further away, they develop a phenotype similar to that of astrocytes, in green, or neurons, in red. The aim of such cell models is to optimise treatments and test new therapeutic approaches.

Artificial intelligence can now be used to detect milk contamination quickly and easily. Certain bacteria such as Pseudomonas fluorescens can contaminate milk during the bottling process. As a result, the milk has to be incubated for several weeks to ensure that it is sterile before being sold. With Red One technology, microorganisms can be detected after only 48 hours of enrichment in the bottle. The sample is deposited and filtered automatically on a membrane. An algorithm is then used to identify any microorganisms present and to monitor them over time. This process is also used to determine the potability of water and the sterility of pharmaceutical products such as vaccines and drugs.

In both flies and humans, mortality increases with age. This is one of the possible definitions of “ageing”. However, the nature of this phenomenon, as well as its molecular or evolutionary origins, are still the subject of much debate. Both these female Drosophila melanogaster have the same chronological age and genotype. However, the life expectancy of the fly on the right is around three days, as compared to over twenty days for the one on the left. The former has reached the Smurf state, a transition identifiable in vivo by means of a blue dye that crosses the intestinal barrier only in individuals that will soon die. These predictive biomarkers for the occurrence of natural death can be used to study the effects of time and of physiological age separately. Will this type of approach enable us one day to predict our own death?

Close-up view of a surface representing hyperbolic space and its boundary at infinity. The existence of such a surface was predicted by the mathematician John Nash in the 1950s. It has now actually been constructed, with the help of computers, by a team of scientists, who are attempting to visualise paradoxical mathematical objects. This surface, resulting from an infinite entanglement of corrugations (or folds), has an astonishing property: the shortest path between a point on its sinuous edge and any other point on this surface is infinitely long. Visualisations of this kind make it possible to explore a new geometry, half-way between that of fractals and that of ordinary surfaces: the geometry of smooth fractals.

Sea foam on the sand, a spoon in a chocolate mousse, a cosmetic cream applied to the skin: although foams are found everywhere, they are still poorly understood. Using air, some soapy water and a recipient with a rugged inner lining, this experiment aims to understand the mechanisms at work when a foam comes into contact with a rough surface. The separation between two bubbles is marked by a soap film; when three of them join up they form a Plateau border (in grey); and when the latter meet in fours they create a vertex (the bright spots). By dipping a glass slide into this dry liquid foam, the scientists are attempting to measure the force exerted on the plate and capture the movement of bubbles in contact with the recipient.

Rotors are used in many applications to exchange energy between a mechanical system (vehicle, turbine) and the surrounding fluid (such as air or water). This image shows the extreme deformations of a small rotor fitted with two flexible polyethylene blades when operating in water. Depending on the frequency of rotation, the speed of the incident flow and the inclination of the blades, large- amplitude deformations may appear in either direction, affecting its performance. In a liquid, this phenomenon can be very pronounced since the forces are proportional to the density of the fluid. Studying these surprising behaviours could lead to possible improvements for tidal turbines and underwater drones.

Ostracods are microscopic crustaceans, most of them no larger than a grain of sand. This specimen of Havanardia societatis comes from a lagoon in French Polynesia and has valves with impressive lateral extensions that are specific to this species. It belongs to a major family that has lived for some 500 million years in marine environments ranging from coastal areas to the ocean depths. Fragile yet resilient, ostracods have survived the five mass extinctions that have punctuated the history of life. Using 3D reconstructions, anatomical comparison between present-day and fossil forms helps to characterise and understand them better, making these crustaceans an important tool for studying changes in biodiversity and environments.

Although you’re more likely to come across Podospora anserina on herbivore dung, this version coloured in the Andy Warhol style could well end up in a museum. Forced here to grow in two dimensions, this microscopic filamentous fungus exhibits a network of hyphae (the filaments) extending over several tens of millimetres. Such a configuration, typical of this type of organism, is thought to enable it to optimise the transmission of information as well as the management of nearby reserves, which are vital to its growth in a frequently hostile environment. In order to elucidate the formation of this network and its growth process, the scientists subject it to external constraints – thermal, nutritional, and mechanical stress – for the purpose of predictive modelling.

In humans, Bethlem myopathy results from mutations in the gene encoding collagen VI, a component of the skeletal muscle extracellular matrix. This rare disease is characterised by muscle retractions and weakness, and a progressive worsening of symptoms, ranging from motor impairment to respiratory failure. The zebrafish is the only animal model that specifically reproduces one of the most common mutations found in patients. It is used to understand the functions of this collagen in the genesis and progression of the disease. This adult zebrafish head has been rendered transparent and labelled for collagen VI, in yellow. The combination of this labelling with the autofluorescence of the structures, in blue, reveals its gills, conjuring up the majestic plumage of the blue-and-yellow macaw.

How is it that small rocky planets such as Mercury or Ganymede, one of Jupiter’s moons, have a magnetic field? It could be due to to “snow” made up of flakes of iron. In the interior of these planets, the flakes, falling from the outer reaches of the liquid core to its centre, could cause turbulence that might potentially generate a magnetic field. To investigate this process, the researchers modelled iron snow in a tank of fresh water using glass beads – as fine as flour – to which they added an orange dye. Initially, a few large flakes fall out of the cloud at high speed. But, as time goes by, billions of small ones slowly fall in continuous streams. The sinking of the dye reflects the impact of snow flakes on their environment.