Time for a second instalment of my ‘weird animal’ series! This time, something a little more cuddly: the pink fairy armadillo.
Category Archives: Biology
Humankind has undergone a dramatic shift over the past few centuries. A combination of industrialised farming and modern medicine has allowed us to completely overcome our biology. We exist in record populations, live for longer than ever, and, most crucially are able to survive a wide range of situations that would have previously killed us. We are a social species. We naturally collaborate and help each other, and don’t stand by while others suffer. As a result of this, we no longer live under the law of ‘survival of the fittest’ – we exist as ‘survival of everyone’.
Evolution needs two things in order to work: genetic variation and selective pressure. Genetic variation is inevitable. It will always exist amongst living populations. Even if you had a theoretical population of exact clones, variation would arise over generations due to DNA copying errors, recombination and genetic drift.
There are differing definitions of death, but it is clear that if a person is unconscious, their heart has stopped and their brain ceased to function, that person has died. They are beyond resuscitation, and their body, now just an object that resembles a person, meets none of the criteria for life. The body is no longer a series of self-sustaining chemical reactions; through the same miraculous processes that allowed it to live, it will begin an inexorable return to the ecosystem from whence it came.
Following death, pallor mortis is the first stage in the process of post-mortem disembodiment. As the heart has stopped, blood no longer circulates, and the red blood cells (being denser than the plasma) drift downwards, away from the upper surface of the body. This is the cause of the paleness of dead skin, and happens within the first half-hour of death.
This is the first in a series of articles about the weird and wonderful of the animal kingdom. You may or may not know about the animals; some will be common, other rare, but all with be noteworthy for possessing an unusual trait or two. The first is about a deep-sea beastie, one that is familiar is shape but not at all in size: the giant isopod.
The giant isopod is a close relative of the common household woodlouse, only massive: the biggest yet found weighed 17 kg and was 76 cm long. They live a solitary life deep at the bottom of the sea, where they scavenge for dead fish and whales in the muddy gloom.
Tens of millions of species inhabit the Earth. From the massive Californian redwood, to the tiny crescent-cup liverwort; the rare blue whale and its prey, the common krill; and from the primitive E. coli to its complex human host, the variation of the natural world is astounding. Surely, on our pale blue dot, there’s only limited room for species to live, so how is it that organisms have evolved to be so diverse?
Speciation is the process by which new species arise. There are several recognised modes, although in reality it works under more of a sliding scale. At one end is allopatric speciation, when members of the same species are geographically separated (through continental drift, etc.). At the other is sympatric speciation, where the organisms are isolated not geographically, but genetically, through processes such as genetic polymorphism. Polymorphism involves relatively small variations in DNA that have such a profound effect on the phenotype that two organisms with slight differences in their genotype are prevented from reproducing, and a single species is effectively split into two daughter species, which evolve separately.