All About Bugs Bugs come in many shapes and sizes The world is full of bugs Some crawl and some fly Some burrow and others build elaborate webs They live in all sorts of climates Some can survive the extreme cold in Antarctica Others live in tropical rain forests Every creature has a unique and important role in its ecosystem The western black widow spider is a venomous arachnid 4
Arthropoda is an animal group that includes insects arachnids centipedes and millipedes These animals are all called arthropods People may refer to them as bugs But insect scientists use the word bug to describe certain insects Not all insects are bugs and not all arthropods are insects Arthropods are split into different categories based on the number of their legs and body parts There are approximately 100,000 known arachnid species The arachnid group includes spiders scorpions and ticks An arachnid has eight legs and two body parts Its lower body is called an abdomen Some scorpions have abdomens that are long and end in tails The abdomens of other arachnids including some spider species are shaped like big round balls The upper part of an arachnid’s body is the cephalothorax An arachnid’s legs are attached to this part of the body The arthropods with the most legs are centipedes and millipedes They typically have between 20 and 800 legs Their bodies have many segments Though centipedes and millipedes look similar to one another there are key differences They belong to different animal The giant African millipede is the largest millipede species in the world 5
Bugs About All groups Centipedes are predators that eat other arthropods Some of them even have venomous bites Millipedes tend to eat plants The groups have different leg shapes Centipede feet are long and lie flat against the ground They have one pair of legs per body segment Millipede feet point downward They have two pairs of legs per body segment Scientists estimate that there are around 8,000 species of centipedes However they believe there are more than 80,000 species of millipedes Insects are the largest category of arthropods There are one million known species of insects The total number might be much higher up to 30 million Insects make up almost 90 percent of all animal life on Earth Insects include beetles butterflies ants and many more Though insects come in many shapes and sizes most of them have some basic anatomy in common They have three parts to their bodies They each have a head a thorax in the middle and an abdomen at the end They have six legs Many have antennae Luna moths and other moth species are all types of insects 6
on top of their heads and most of them have wings One thing all of these animals have in common is that they don’t have bones They are invertebrates Instead of a skeleton on the inside arthropods have exoskeletons An exoskeleton is made up of a hard material called chitin It works like armor But the exoskeleton cannot grow with the creature In order to grow larger an arthropod must molt or shed its exoskeleton Some juvenile insects look very different from their adult forms For instance the monarch caterpillar transforms into the monarch butterfly Insects arachnids centipedes and millipedes can be pests Some may spread diseases and destroy crops However arthropods also play crucial roles in producing food and pollinating flowers Some eat weeds Others eat all sorts of dead things which helps keep the environment clean These creatures are essential parts of the world Honeybees play important roles as pollinators 7
