Arthropods

=  = =  Arthropods  =



__** What is it? **__  • Arth ropods are animals known to be insects, crabs, centipedes, and spiders.  • Each of those mentioned has an __ exoskeleton __, which is anoutside layer that protects the animal. It is made up of chitin, a carbohydrate. The body is divided into different __ segments __ and __ appendages __ such as antennas or legs are attached to the main body.   __** Way Back Then... **__  • Arthropods are said to have appeared 600 million years ago.  • As they evolved they began losing appendages such as less legs. Though they became stronger, adapting as the time went by.  • Now arthropods can be found in freshwater, land and air. __** Form and Function **__  • They have a difficult organ system that helps them complete different functions.  • To breathe, they use tracheal tubes located throughout the inner body. They also release waste through saclike tubes, meaning they have an open circulatory system. __** Feeding and Excretion **__  • Arthropods can be herbivores, carnivores, and omnivores.  • They can be bloodsuckers, filter feeders, detritivores, who use waste as food,or parasites. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Since an arthropod can range from a caterpillar to a spider, their mouth can vary. Whether they have pincers or fangs. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Overtime the arthropods mouth have evolved so that they are able to feed on more than one thing. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • The saclike tube is called a malpighian tubule. It is an organ that takes out waste from the blood and include them to their waste. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Since some arthropods live in the water, they use diffusion to extract waste to the water. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;">__** Respiration and Circulation **__ <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Most arthropods living on land use tracheal tubes to breathe. However, they breathe in and out through spiracles, tiny holes around the body. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Book lungs can be found in spiders. They are organs that have respiratory tissues piled like books. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • For those that live in water, like crabs, they breathe through gills that can be considered featherlike. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • An open circulatory system is one without veins, it is not restrained from certain parts. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • The heart pumps blood that enters tissues. Then it leaves the vessels and goes through small openings. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Around the heart is a small hollow area where the blood comes together and enters the heart once again. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;">__** Response, Movement and Reproduction **__ <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • An arthropods brain works similar to ours. It send and receives signals from the body. Around their esophagus are two nerves that attach to the brain and a lower nerve cord. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Around this nerve cord are groups of nerve cells called ganglia's which take part in directing the movement of an appendage. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • An arthropods movement is controlled by the nervous system. The muscles pull and contract the exoskeleton. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • those who live on land have internal fertilization. Those who live in water can have either internal or external fertilization. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Some arthropods may have a that inserts sperm into the female, others leave it for the female to pick up. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • If fertilization is external, it is occurring outside of the female where the eggs that she has released are and the male places sperm on the eggs. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;">__** Crustaceans **__ <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • These are aquatic animals like crabs, lobsters, and shrimps. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • They usually have four antennas and either two or three sections of the body. Their mouth opening is called a mandible. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Crayfish: the head and the thorax, behind the head, make up the cephalothorax. This contains most of the organs inside. Behind the cephalothorax is the abdomen, the back part of the body. Coating around the cephalothorax is the carapace which is part of the exoskeleton. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • The antennas in crayfish are just for sensory although in some crustaceans they can be used for filter feeding or even swimming. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;">__** cont.... **__ <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Decapods is the largest group of crustaceans. It includes crayfish, lobsters, and crabs. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • They contain five pairs of legs, the claws are the first two called chelipeds. Then 4 pairs of walking legs and the rest are swimmerets, small appendages used for swimming. The last segment is the tail. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Another group are barnacles. Overtime they lost their abdomen and mandibles. They attach to rocks or many on whales. They use appendages to grab food and bring it to themselves <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;">__** Spiders and friends **__ <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Chelicerates is the group consisting of crabs, spiders, ticks, and scorpions. They have two sections of the body, and most have four pairs of legs. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Unlike the other arthropods, these d no have antennas. Though just like them they have a cephalothorax containing the head and walking legs, also the abdomen with all other organs. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • The have two mouth parts, the chelicerae that are small fangs to stab and paralyze pray and the other are pedipalps which are longer and used for grabbing. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • They are divided into two groups : horseshoe crabs and arachnids, containing spiders,mites, ticks and scorpions. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;">__** cont... **__ <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • The horseshoe crab is not a crab but rather more related to the spider. However they have a hard shell like a crab and are about the size of a small turtle. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • The spider paralyzes their pray and must form it into liquid to eat it. The stomach pumps and extracts tissues then passes them through the rest of the digestive system. All spiders contain spinneretes which are organs that produce silk. All spiders produce silk and it is harder than steel! <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Mites and ticks are considered parasites. They feed off of another host usually sucking its blood or fluids. Their mouth is usually needlelike and it is so strong that by trying to pull one off might just leave the cephalothorax attached! <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Scorpions contain oversized claws to grab their pray and a venomous stinger attached to their abdomen to kill prey. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;">__** Insects and Friends... **__ <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • Today, the group that contains more than any other are insects, or uniramians. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • They have jaws, only one pair of antennas, and three segments of the body. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • For the centipede each body segment has two legs. They are carnivorous and use venom to kill prey with claws. They can only live in moist areas because their bodies lose water easily and their spiracles do not clothes so they are not waterproof. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;"> • The millipede although, has four legs per segment. They eat dead plant material and are very shy. Because the bottom is soft, when they are touched they roll up into a ball or sometimes excreting chemicals. <span style="direction: ltr; display: block; margin-bottom: 0pt; margin-left: 0.38in; margin-top: 6pt; text-align: left; text-indent: -0.38in; unicode-bidi: embed; word-break: normal;">