What a Strange Idea that tumours could become mothers!
I have mentioned in a previous blog that it was possible to create mosaic specimens from the fusion of embryonic cells of different donors at an early stage of development. Such mosaic animals are often also called “chimaeras” (after the Greek mythological beast that combined features of lion, goat, and dragon) and they can be extremely useful “tools” for the genetic researcher. —>—>
The Turtle is a Gold medal diver
With a bit of exercise and healthy lungs, anybody can do what I could do even a few years ago: holding my breath and staying underwater for 2-3 minutes. The lazy South American sloth isn’t a good diver, but should the branch it clings on break off and the animal finds itself under-water, it can indeed hold its breath for 10-15 minutes; it’s simply quite a tough animal. But there is, of course, a limit to the duration anyone can stop breathing and ducks, for instance, can do much better than the average human. They, and other diving vertebrates as well, slow down their heart beats during the under-water period, which allows them to remain without oxygen longer in the submersed condition than in air with a normal heart beat. But while a duck’s dive would rarely exceed 10 minutes, that of the emperor penguin can last for 20 minutes and may take the bird to depths of around 200 m. —>—>
What can a frog’s egg teach us
Hardly anything in zoology could be more exciting than to observe how from an egg cell a whole new individual develops. Unfortunately for the curious person very often the developing egg is hidden from view as in mammals and sometimes it is so small that it is impossible to examine what precisely goes on. But there are some animals which allow even children without the aid of a microscope to observe the embryo and how it grows inside the egg. One example are freshwater pulmonate snails like Planorbarius corneus (the ramshorn snail) or Lymnaea stagnalis (the common pond snail). Their eggs, attached in clusters of up to 40 or so on the glass walls of an aquarium make observations easy. But other, and even bigger and therefore more suitable eggs allowing one to follow the changes that go on inside them are those of frogs, toads and newts. In the gelatinous eggs of these amphibians, rice grain sized in newts but up to the size of peas in frogs, one can see the entire developmental process through the transparent egg membranes virtually with the naked eye (although a hand lens would help, of course).