Insects, arachnids, centipedes and crustaceans are all arthropods. Arthropods have a wide variety of respiratory systems. The body of insects is divided into three regions: a head, a thorax, and a clearly segmented abdomen. Most insect species also have two pairs of wings, although these are absent in a few very primitive species and have been reduced in others, becoming nonfunctional or adapted for a different purpose. They include insects, crustaceans lobsters, crabs, shrimp, crayfish , millipedes, centipedes, horseshoe crabs, arachnids spiders, ticks, and mites and sea spiders. The spiders, mites, scorpions, and other arachnids are almost entirely land animals, as are the extremely diverse insects.
Most species of crustaceans live in water that is, are aquatic , although a few such as wood lice and land crabs occur in moist habitats on land. Super-Order 1 : Syncarida : It includes two orders. The class Diplopoda consists of the millipedes, a group that includes over 8,000 described species. The more primitive species tend to be filter feeders. A few species are transmitters of bacteria or viruses that cause diseases such as malaria, , encephalitis, and. Molting allows for rapid growth until the newly secreted exoskeleton hardens.
Arthropods have internal fertilization, and they lay eggs. Arthropod exoskeletons are made of , a non-cellular material secreted by the. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum. Some are ectoparasitic and vectors of disease. The arthropods constitute over 90% of the animal kingdom and are classified in the phylum Arthropoda. The first pair of trunk appendages or maxiilipedes form the large prehensile poison claws. However, some estimates predict large numbers of species of arthropods that have not yet been described and named by biologists.
Webs are used for a variety of purposes in different species. The sub-class is divided into 5 orders. The system plays a role in oxygen exchange and assists with molecular nutrient intake. There are more contrasts, but this should do for … now. Two pairs of legs are present on each segment. Some tagmatization occurs in the annelids, i. Class 3 : Insect a : These are terrestrial and aquatic arthropods.
Members of this order have highly sophisticated social structures. Well, some astonishingly tiny arthropods are parasitized by even more incredibly tiny arthropods! The body is composed of a head region bearing a pair of antennae, a pair of mandibles, and two pairs of maxillae, and a trunk region with one pair of legs on each segment. Respiration is by gills or tracheae. Once their hardened, old coverings crack and shed, they sport roomier, albeit soft, exoskeletons. In some species, lipids, proteins, and may also contribute to the exoskeleton. Some species have gills, while others employ tracheae, or book lungs. The majority are filter feeders.
And the diversity is astounding. Another echinoderm is the prickly sea urchin. Together, these ommatidia form a single working eye. The orange ball of eggs contains thousands of baby crabs just waiting to hatch. Contributors Phil Myers author , Museum of Zoology, University of Michigan-Ann Arbor.
Ex : Mysis b Order: Cumacea : They are smaU and minute. In spite of their vast differences, all insects have certain traits in common. The cuticle of crustaceans, unlike that of other arthropods, contains calcium deposits. Characteristics of Arthropods There are many different types of animals that are grouped together as arthropods. A is made up of many separate units for receiving light, each with its own lens.
However, bees are critical pollinators in the plant world and are therefore extremely important. You probably already know that insects have six legs, setting them apart from eight-legged arachnids. They are sometimes grouped with the hexapods. Excretion is by antennal glands. Now a days these 4 groups of moriapoda are regarded as separate classes.