Fish without eyes
It is sometimes quite shocking what some people think the work of an animal biologist consists of. One day, when visitors to our house took a look at my aquarium and admired the fish in it, my ears had to hear the following comment: “Very interesting, but doesn’t it hurt them when you remove their eyes?” “What do you think?”, came my reply, “they are blind fish. They never have any eyes! They are Mexican cave fish, Astyanax mexicanus.” Stupid visitors (I did not say that), but they obviously did not know that some species of fish are naturally eyeless.
Life’s Secretive Pioneers in the Sandy Pits
Many animals love to explore or spend most of their lives in the gaps and spaces created by piles of stones or wood: some cats like confined spaces, mice certainly do, and ants just love them. But ants can, of course, make use of much, much smaller crevices than bigger animals can. However, what about the sand on the beach? It is fine and seems compact, but there is always a small volume of interstitial space between the sand grains: could anything possibly be living in there? I bet no beach-frolicking folk ever think about that, but sure, further down the beach towards the sub-littoral you can step on shells buried in the sand and may get bitten on the toe by a crab that has sheltered in the substrate while further up, along the zone of decaying algal debris, you may encounter beach-hoppers and sand flies. But in between these two horizontal layers, would there be any life at all in the sand? —>
And spiralling around as well
A look at the diminutive, fantastically diverse life forms and their activity in a single drop of water can be a truly amazing experience – provided of course you have not chosen tap or rainwater. A drop of water from the edge of a weedy pond (or a puddle near a penguin rookery, which was my source for a study) examined under a simple light microscope does, however, reveal a microcosm of hidden life. In amongst the jittering soup of miniature plants and animals, it is the group of ciliated protozoans that are the greatest attention getters. The smallest may not even reach 50 microns, while Paramaecium and Euplotes maximally attain 1 mm and the biggest like Spirostomum may reach a length of 3-4 mm.