Arthropods-Insects And Their Relatives

would you think that this marine animal a lobster living in the ocean is related to the grasshopper an animal that lives only on land or that both grasshopper and lobster are related to this spider and also to this millipede yes animal groups the group called arthopods the name arthropod comes through Greek words so arthropods are animals having jointed legs these diagrams show us the legs of a millipede a grasshopper a spider and a lobster all are jointed in several places arthopods share other characteristics besides jointed legs these characteristics are an exos skon or skeletons pigmented body with organs and appendages attached let's look at the ex the frame that forms its body unlike animals with backbones the lobster skeleton is outside its body rather than inside it is an exoskeleton perhaps you've seen an empty exoskeleton of a young grasshopper that outgrew its covering the spider's exoskeleton is harder to see because of the hairs growing on the animal's body but the shiny exoskeleton of the milipede can be clearly seen so our examples have shown that all arthropods have an EXO or outside skeleton what about the third characteristic a segmented body with organs and depend es attached let's examine the millipede first attached to most body segments are pairs of jointed legs legs are among the body parts called appendages on the millipedes head can be found several other appendages these mouth appendages help tear plants into pieces small enough for the milp to eat so the milliped chose another characteristic of arthropods specialized appendages attached to a segmented body the spider's body too is divided into segments attached to the body are such appendages as jointed legs on the spider's head are other appendages such as specialized grasping surfaces which the spider uses to hold its food specialized chewing appendages can be found in the grasshopper the grasshopper's other appendages include the jointed legs attached to a body made up of segments by looking at the underside of a lobster we can see that its body too is divided into segments again there are the jointed legs common to arthropods and other appendages such as this pincer like claw which is used to catch food the lobster then and all other animals called arthopods Share three common characteristics jointed legs outside or exoskeletons and a segmented body with organs and appendages attached though they share these three characteristics all arthropods are not alike they have been grouped into four main classifications the millipede we saw is an example of the classification called myriapods the grasshopper is an example of the classification insects the spider is an example of the classification ARA nids the lobster is an example example of the classification Crustaceans this chart shows the names of the four main classifications and the examples we've seen of each myriapods such as the millipede are sometimes called thousand leggers they are usually found in dark moist places insects are the most common of the arthropods numbering many thousands of species among the various species of insects there is a wide range of color and size this fairly large and beautiful insect the dragonfly lives most of its life alone while other insects such as ants live together in groups or colonies ants and other insects such as moths and butterflies go through several stages of development and growth similar to insects in some ways are the arachnids the arachnids include all the many species of spiders among the spiders are tarantulas which are often found in dry desert areas however arachnids as well as insects are widespread in many parts of the world also widespread are the arthropods called Crustaceans most Crustaceans live in or near the water water some Crustaceans like this fiddler crab are quite large but these almost transparent Crustaceans called daphnia are extremely tiny and can hardly be seen by the naked eye the picture of this dnia for example has been magnified hundreds of times alt together the many species of animals that make up the four classifications of arthropods myriapods insects arachnids and Crustaceans number over 600,000 known species many are helpful to man many are harmful insects like the honeybee are very helpful to man honeybees pollinate certain plants and in their hives honey bees produce honey and wax both products useful to man also helpful to man are these insect young or larvey they are the larve of the silkworm moth the cocoons spun by these moth larv are processed into silk threads and used in cloth making by man other insect larv are quite harmful these are the larv of the common seen here feeding on a piece of Woolen clothing another common insect pest is the housefly this insect is well known known as a carrier of dirt and disease in controlling such insect pests as the housefly many of the arachnids including spiders are helpful to man spiders such as this one spin webs in which houseflies and other insects are trapped and then eaten thus spiders help to control insect pests however several species of arachnids among them the Scorpion are harmful to man such arachnids have a specialized organ in the tail commonly called a stinger this organ can inflict painful and sometimes fatal stings the group of arthropods called Crustaceans includes many species that are useful to man this crayfish is a freshwater crustacean crayfish help keep water clean by acting as scavengers eating decayed plant and animal matter crayfish are sometimes eaten by man these shrimp like most edible Crustaceans inhabit saltwater edible crustations are an important part of the foods from the sea that are eaten by man we have seen then that the many species of arthropods are important to the lives of men whether these arthropods are helpful or harmful how do we determine that a certain animal is an arthropod what three characteristics should we look for first we must look for several pairs of jointed legs second inside the animal's body third we must look for a segmented body with organs and appendages attached animals that share these three character istics belong to the group of animals called arthopods the largest and most numerous group