Fran Hernández Heras graduated in physics and mathematics at the University of Valladolid. He then completed a PhD in Zoology in the University of Cambridge, as a member of Trinity College. Currently, he does research on collective behaviour in the Champalimaud Centre for the Unknown, Lisbon.
The neuronal membrane, like membranes surrounding other cells, is mainly formed by a lipid surface impermeable to ions. It is only through ion channels, small protein pores embedded in the membrane, that ions can cross, allowing electrical current to charge or discharge the neuron. The inclusion of ion channels in a membrane, determines its electrical […]
In a previous article I wrote about the high speed attacks of the mantis shrimps. However, my favourite feature of these crustaceans is their unique eyes. They have two apposition compound eyes, typical of many diurnal insects and crustaceans but unusual in how freely they can move on their stalks. The eye forms an image […]
If we were to ask a bunch of science geeks about their favourite animals, I have no doubt that the mantis shrimps would top many rankings. The mantis shrimps (or stomatopods) are an order of marine crustaceans, typically inhabiting the colourful coral reefs in tropical or subtropical seas. They are neither shrimp nor mantis, although […]
As the Hungarian mathematician Alfréd Rényi famously put it (although usually misattributed to Paul Erdös), mathematicians are devices for turning coffee into theorems. Other people drink coffee for a variety of reasons, and considering that coffee is very far from being the only popular beverage containing caffeine, it is not difficult to believe that caffeine […]
When the nymph Calypso was finally convinced by Hermes to let Odysseus go back to Penelope and his island, she gave the Greek hero very precise instructions. After leaving Calypso’s island, Ogygia, Odysseus should “keep [the Great Bear that men call the Wain] to larboard as he crossed the waters”. In the northern hemisphere, all […]
Cajal famously described the fly visual system as “stupendous, indeed disconcerting, and with no precedent in other animals”. By comparison, the vertebrate retina seemed “gross and deplorably simple”. Now we know that this simplicity is only apparent, but we can use the more clearly structured fly retina to help us study basic problems in visual […]
It was commonly assumed that no new neurons are formed in the adult mammalian brain, even after the first results showing neurogenesis in rodents were published in the 1960s. Further work in mammals and birds during the 80s contributed to change the scientific consensus, but it was the discovery of adult neurogenesis in humans in […]
In our eyes, the cornea and crystalline lens project an image of the world onto the retina. There, this image is sampled by the rods and the cones —the light-sensitive cells of the vertebrate eye—, coded as a sequence of electrical signals and preprocessed by other neurons before being sent to the brain via the […]
Bees visit flowers to obtain nectar (a sugary liquid) and pollen (their source of fat and protein). During foraging trips, bees do not choose flowers at random. For example, as first pointed out by Aristotle, bees visit only one type of flower in each of their foraging trips. How do bees recognise flowers? Colour textures […]
About 95% of the photoreceptors in our retina are rods, which we use for nocturnal vision, since they can detect single photons. During the day, rods saturate, and we use the other 5% of photoreceptors, the cones, which mediate color vision and do not saturate even at the highest light levels. There is still a […]