They are mostly carnivorous many mites are herbivores. Most secrete powerful digestive enzymes which are injected into the prey to liquify it. Once dissolved in its own epidermis, the prey is sipped like a root beer float. Order Scorpiones 2, sp.
Scorpions date back to the Silurian, about mya, and may be the first terrestrial arthropods. Order Araneae 32, sp. Not all spiders spin webs. Wolf spiders are the tigers of the leaf litter, and the common jumping spider leaps several times its body length to catch its prey. Spiders use pedipalps as copulatory organs. Spiders breathe by book lungs. Order Acari - 30, sp. Most are very tiny, less than 1 mm long. The thorax and head are fused into a single unit cephalothorax. Order Opiliones 5, sp.
It has an oval body with extremely long legs, which they frequently lose in various accidents and brushes with predators. They are predators, herbivores, and scavengers. Look at them closely next time you see one.
They carry their eyes atop a little tower on their back weird! Crustaceans are mostly marine, and dominate the ocean to the same degree that insects dominate the land and air. Despite their aquatic diversity, there are very few terrestrial crustaceans, just as there are very few truly aquatic insects. Crustaceans have biramous appendages. Each leg has an additional process, like a little miniature leg branching off from the main leg.
Many groups of crustaceans have lost this extra appendage during subsequent evolution. The Order Decapoda have five pair of walking legs, and include the familiar crabs, lobsters, and crayfish. The first pair of appendages are usually modified as antennae. Crustaceans have two pair of antennae. Another set of anterior appendages are modified as mandibles, which function in grasping, biting, and chewing food.
Male crayfish also use one pair of legs as a copulatory organ. All crustaceans share a common type of larva called a nauplius larva. They are one of the few successful terrestrial crustaceans. They feed on decaying vegetation in the leaf litter. Uniramians have a single pair of antennae, and uniramous appendages. They probably evolved from oligochaete worms. Class Chilopoda - 2, sp. Centipedes dwell in damp places under old logs and stones.
They are carnivorous, eating mostly insects. They are highly segmented, and have one pair of legs per segment. The first trunk segment bears poison fangs. Centipedes are very dangerous, and their bite is extremely painful. Class Diplopoda - 10, sp. Millipedes share the same habitat as centipedes, but they are mostly herbivorous, feeding on decaying vegetation in the leaf litter. Animals that feed on detritus are called detritivores. Each segment of the millipede is actually two segments fused together hence the double set of legs.
They can secrete a defensive fluid that smells bad, and a few species actually secrete tiny amounts of cyanide gas to protect themselves! Class Insecta - , sp. If we knew all the different insects on Earth, there could be as many as 30 million species. Insects evolved about mya, with cockroaches and dragonflies among the first to appear. Insects have a head, thorax, and abdomen, with three pair of legs 6 legs on the thorax.
Crustaceans have legs on the abdomen as well as on the thorax. Most insects have one or two pairs of wings. They are the only invertebrates that fly. Most have compound eyes , and can communicate by sound and scent, using powerful chemical hormones called pheromones. Insects have extremely elaborate mouthparts, consisting of pairs of appendages fused into a lower lip labium , and an upper lip labrum , with other appendages called maxillae aiding in chewing. These mouthparts are highly modified in various groups for chewing, sucking, and piercing.
Insects undergo metamorphosis as they develop, changing from one form to another as they mature. The juvenile stages look like tiny versions of the adults. Their larvae are often radically different from the mature adult like the butterfly and the caterpillar.
They not only look different, they live in different places and eat different food. Observe the preserved arthropods on display. How do the various groups use their legs to walk, swim, feed or mate? Watch the way the millipede moves. Look at the legs. See how the waves of muscle contraction pass down through the segments? Typically insects have:. While insects typically have two pairs of wings, some only have one pair, such as flies.
A few insects have no wings, like ants, fleas and lice. Insects are the only invertebrates that can fly. Since there are three-quarters of a million insect species, it is best to just look at some of the common ones. They include:. Arachnids are eight-legged arthropods with no wings or antennae. Most arachnids live on land; but, a few species can be found in fresh and saltwater habitats. The three main orders of arachnids are:. All crustaceans have ten legs or more and most of them are found living in water.
The majority of aquatic crustaceans live in saltwater, but a few live in lakes and rivers. Woodlice are one of the small numbers of crustaceans who live on land. The number of species of crustaceans is over 40, Some of the common ones include:. Myriapods are the most specific group of arthropods, but there are still over ten thousand species out there. Their characteristics include:. While most myriapods are classified as centipedes or millipedes, there are thousands of species to discover.
Crustaceans usually have two body segments, the cephalothorax orange and the abdomen green. The number of appendages on crustaceans can vary, and many of them have large claws, used for capturing prey. Color the claws on the lobster brown and the large legs attached to the thorax blue.
Notice the little legs attached to the abdomen on the lobster which the animal uses for swimming. These appendages are called swimmerets - color dark blue. Crustaceans also have antennae - color grey. This animal belongs to an entirely different class from the others. Centipedes have long flat bodies and many legs. In fact, the word "centipede" means "hundred legs", though centipedes can actually have more or less than a hundred. Color the legs of the centipede blue and each of its body segments red and the antennae grey.
Centipedes are often poisonous and are related to the non-poisonous millipede. Insects Insects have three body segments, the head, thorax middle region and the abdomen.
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