Sociable weavers construct permanent nests on trees and other tall objects. These nests are the largest built by any bird, and are large enough to house over a hundred pairs of birds, containing several generations at a time. The nests consist of separate chambers, each of which is occupied by a pair (sometimes with offspring) roost and breed.
Picture: Dillon Marsh / Rex Features (via Tiny weaver birds make huge nests on telegraph poles in the Kalahari desert - Telegraph)
This incredible invertebrate is Scolopendra gigantea, though it also goes by the names Amazonian giant centipede, Peruvian giant yellow-leg centipede and the bat-eating centipede. Bats are but one of many vertebrates Scolopendra gigantea preys on - it has been known to devour frogs, toad, small lizards, snakes (up to around 24 cm long), mice and birds the size of a sparrow. Though it has a potent venom, it possibly is the least remarkable part of how it preys on bats.
In their paper on the subject, Molinari et al identified 3 ways Scolopendra gigantea hunts bats. The first two suggest that it crawled up the bat cave wall to the ceiling and either found a perching bat or waited for a bat to perch near it. The third is the most incredible, describing how the centipede could hang from the cave ceiling and grab a bat in midflight, quickly immobilizing it with venom delivered via its forcibles (or poison claws).
Whichever option it is (and Molinari et al appear to lean towards the third), when it attacks the bat it injects its venom near the brain. The centipede then sets to work devouring its meal, holding the bat with its first eight pairs of legs and holding on to the ceiling with its last five to eight pairs. This feat is even more incredible when you consider the difference in mass between predator and prey - while the centipede may weigh around 9.0-9.5g (before eating) it has been observed in this position eating bats weighing around 16.5g.
In 2011, the Postal Service celebrates the achievements of chemist Melvin Calvin, botanist Asa Gray, physicist Maria Goeppert Mayer, and biochemist Severo Ochoa.
Melvin Calvin (1911-1997) advanced our understanding of photosynthesis and conducted pioneering research on using plants as an alternative energy source. He won the Nobel Prize in chemistry in 1961. The stamp art includes a photograph of him taken by Yousuf Karsh. The background shows excerpts from the carbon cycle, and chemical symbols and structures he used to represent the process of photosynthesis.
Asa Gray (1810-1888), one of the nation’s first professional botanists, advanced the specialized field of plant geography and became the principal American advocate of evolutionary theory in the mid-nineteenth century. The stamp art features illustrations of plants studied by Gray and the words “Shortia galacifolia” in Gray’s handwriting.
Maria Goeppert Mayer (1906-1972) developed a theoretical model that helped explain the structure of the atomic nucleus; for this work she became the only woman other than Marie Curie to win a Nobel Prize in physics. The stamp art combines photographs of Mayer with a chart and a diagram she used to illustrate aspects of the atomic nucleus.
Severo Ochoa (1905-1993), a biochemist, was the first scientist to synthesize ribonucleic acid (RNA) and competed in the race to decipher the genetic code. He won the Nobel Prize in physiology or medicine in 1959. The stamp shows Ochoa in his laboratory in 1959, along with figures representing some of his work on protein synthesis.
La Edad Mesozoica es conocida comúnmente como “la Edad de los Dinosaurios”, y la razón es que estas criaturas dominaban los ambientes terrestres. Sin embargo, los océanos Mesozoicos también tenían su buena cantidad de criaturas, como los Ictiosaurios, poderosos nadadores con grandes mandíbulas y colas con forma de media luna que llegaban a tener tamaños que ningún delfín moderno podría llegar a tener, llegando a los 15 metros de largo.
Los Ictiosaurios aparecieron por primera vez en el Triásico, aproximadamente al mismo tiempo que los primeros dinosaurios y sobrevivieron hasta la mitad del Cretácico, hace unos 110 millones de años. El primer Ictiosaurio fue descubierto en 1811 por una niña en los acantilados alrededor de Lyme Regis, en Inglaterra.
En esta época también se encontraban los Plesiosaurios, que han sido descriptos como “serpientes unidas con cuerpos de tortugas”. Estos animales tenían cuerpos con forma de tortugas con cuatro largas aletas, colas cortas y puntiagudas y cuellos largos similares a los de las serpientes. Sus cabezas relativamente pequeñas estaban armadas con afiladísimos dientes. Aunque nada se sabe a ciencia cierta sobre sus hábitos de apareamiento, podrían haber tenido las mismas prácticas que las tortugas modernas. El Plesiosaurio más grande llegaba a tener una longitud de 14 metros, de los cuales más de la mitad pertenecían a sus cuellos.
Otros animales marinos gigantes eran los Pliosaurios, de los cuales se creía que estaban relacionados con los Plesiosaurios, pero estos tenían cuellos más cortos, y cabezas y mandíbulas más grandes. El Pliosaurio más grande era el Kronosaurus, que medía 12.8 metros de largo.
Los Ictiosaurios, Plesiosaurios y Pliosaurios estaban tan perfectamente adaptados a su ambiente que sus esqueletos casi no demuestran similitudes con otros reptiles. Su posición y relación taxonómica con los reptiles terrestres permanece incierta.
Falls of fire por Nikhil Shahi
“Every year for a few days in the month of February, the sun’s angle is such, that it lights up Horsetail Falls in Yosemite, as if it were on fire. It truly is an amazing experience”
