Ooey Gooey was a worm, a wiggly worm was he He climbed upon the railroad tracks, the train he did not see. Ooey Gooey!”
Edwin Larson
Now we have come to the last of the kingdoms – the Kingdom of Animals – a kingdom filled with oceans and lakes, forests and mountains, every type of environment on Earth. It is the noisiest kingdom, too, being home to the only creatures that we can hear. Most of our favorite creatures call this kingdom home, from elephants to ants. There are so many surprising, wonderful creatures to talk about that we will visit this kingdom in several parts. The first group that we will see are the invertebrates – those animals without backbones (also called spines). If you reach behind your neck and feel lump there and the valley that runs down your back, you will be feeling your backbone. Most animals, however, do not have this set of bones. Its lack, though, allows for great variety, from wispy jellyfish to armored crabs to slimy worms.
Some of the smallest of these animals, those that are so small they can only be seen with a microscope, were first described by Antonie van Leeuwenhoek (lay-ven-hook), a Dutch hat maker. That’s right, one of the most important discoveries in biology was made by someone who was not even a trained scientist. He was just a shop owner in the town of Delft when he became interested in things too small to be seen with the naked eye. He managed to figure out how to make his own magnifying lenses (some of the best for his time period), and then the real work started.
He spent hours and days and weeks (in his spare time, as he said himself) looking at all manner of things to see what there was to see. He looked at rain water and melted snow and pond water. He looked at muscles and blood and insects. And he saw amazing things. He recognized that what we see every day is made of smaller things – what we now call cells. He saw blood cells, scales of butterfly wings (he thought they were feathers!), worms from sick sheep, and most amazingly that water often home to many, many, MANY tiny living things. He carefully studied samples of water from several different sources over the course of weeks, noting his observations each time. He wasn’t a scientist, but he thought and worked like a scientist, and his insatiable curiosity about seemingly everything changed the way that we think about the world. Just like van Leeuwenhoek, you can be a scientist if you closely observe the world around you and keep asking questions.
Among the first microscopic creatures described by van Leeuwenhoek were rotifers – a nearly clear tube-like animal with a crown of feather-like “fingers” to brush food into its mouth (do you think we should sweep food into our mouths at meals?). Microscopic creatures continue to be discovered today as we look deeply into more and more places, such as the miniscule cucumber-like creature (Limnognathia, if you care for the name) which is found only in pools of water in Greenland; it is considered to be so different from every other kind of animal that it is in its own region in the Kingdom.
Of course, not all invertebrates are so small. Sure, there are somewhat small creatures like shrimp, bumblebees, and amazing proboscis worms that shoot out a tongue-like proboscis to kill their prey with venom, but some invertebrates get simply massive. There are giant tube worms that are as tall as an elephant and live in the deep ocean, the lion’s mane jellyfish that is as long as three and a half school buses, and the king of invertebrates, the colossal squid (even bigger than the more famous giant squid) which are not as long as the lion’s mane jellyfish but can weigh as much as three gorillas.
By far the most common animal in the whole world are insects – busy bees, cheerful ladybugs, colorful beetles. With over 1 million species that we know of, insects make up half of all known creatures of any kind. We often think of these creatures – as well as their close relatives spiders – as bugs, nuisances that bother us when we go outside and creep us out inside. These little animals are amazingly important in helping our food to grow, removing dead plants, and providing us with honey and silk. Insects have thrived all over the world (even Antarctica!), and, beyond their beauty, they play important roles in their ecosystems such as controlling the numbers of other bugs and being food for larger animals like frogs and anteaters.
Another thing that is great about insects is that they are easy to identify just by looking at them. All insect have six legs (and no other animals do). You would find those legs on the thorax, or middle segment, of its body. Most insects have two sets of wings (four wings total); you will also find those on the insect’s thorax. In front of the thorax, you would find the insect’s head, which, like ours, has its eyes, mouth, and antennae (ok, we don’t have antennae…perhaps that is why there are so many more insects…) Behind the thorax, you will notice a third body segment called the abdomen, especially if that insect is a bee; the abdomen is where you will find an insect’s stinger (if it has one), as well as its stomach and most other organs. Insects have no bones; instead, they have a hard outer covering called an exoskeleton, which gives their bodies shape and protection. Insects live all around us, so try to find some and see its body parts!