Kingdom Rnimalia

Phylum Rrthropoda

Phylum Chordata

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S K I N is moist and glandular and has no external scales.

rays.

NOSTRILS 2, connected to mouth cavity and with valves to exclude water. The eyes often have movable lids, the eardrums are external on toads and frogs, and the mouth is usually with fine teeth. The tongue is protrusible.

The tropical tree toad ingests its food through the mouth, and digestion occurs in the stomach and small intestines. The toad (an animal) needs food to supply materials for growth and maintenance, for replacement or repair of parts, for energy to move, and for producing sex cells. Animals require complex organic substances as food to obtain these by eating plants or other animals. Their food must be subjected to the physical and chemical changes of digestion, before it can be absorbed and used in the body. The system serving this function consists of the digestiae tract and the digestiae glands. This tract is essentially a tube that extends from the mouth to the anus, being of different diameter and structure in its several parts.

enzymes in the toad's and intestine include pepsin, trypsin, and erypsin, all of which act on proteins; lipase, which acts on fats; and amylopsin and maltase, which act on starches. The muscular movement that moves the food along the digestive tract is peristalsis. Some absorption may occur in the stomach, but most of the mixed and finely divided contents is passed through the pyloric ualue at the posterior end and enters the small intestine. This is where most of the absorption and digestion occurs. Undigested residues are slowly moved by peristalsis into the large intestine, are formed into feces, and ffnally passed out through the cloaca and anus. Absorbed materials travel by way of blood and Iymph to

various parts of the parts of the body for immediate use in growth or activities for storage. Much reserve food is stored in the liver as glycogen (animal starch), a carbohydrate that can be converted into glucose for use in the body as needed. Fat is stored mainly in the fat body.

C I RCULRTI ON

The transport of materials within the body is performed by the circulatory system. Its principal functions are to carry (1) oxygen and carbon dioxide between the respiratory organs and body tissues; (2) digested foods from the digestive tract and water from the skin to other organs; (3) stored foods from place to place as needed; (4) organic wastes and excess minerals in solution, together with water, to the excretory organs; and (5) hormones from the endocrine glands where they are produced to the places where they are used.

The circulatory system consists of the heart, arteries, capilbries, veins, and Iymph vessels, together with fluid blood and Iymph.

BLOOD is the clear fluid pbsma containing free cells, or blood corpuscles.

HERRT is a connected series of chambers enclosed by muscular walls. It consists of (1) a conical thickwalled uentacle posteriorly; (2) the left and right auricles anteriorly, with thin muscubr walls: (3) a thin triangula sinus uenosus dorsally; and (4) a stout tubular truncus arteriosus that leads forward from the anterior base of the ventricle. Ualues between the chambers backward flow of blood.

RRTE R I E S are blood vessels that carry blood away from the heart.

CRP ILLRR IES have walls only of endothelium and are scattered densely among tissue cells of the body. Here food and oxygen ar~s distributed through the capilbry walls, some plasma and Iymph cells escape, and both carbon dioxide and other wastes are taken into the blood.

UE I NS The capilbrles join to form small veins, and these in turn combine into brger veins that cary blood toward or to the heart.

LYMPHATIC UESSELS are a part of the Lymphatic System and are delicate in structure. The vessels are of varied diameter and shape that penetrate the organs and tissues that are difficuH to see. Frogs and toads unlike other vertebrates, have also several large Lymph Sacs or spaces between the skin and body. The watery Iymph in these structures contains leucocytes but lacks red blood cells and some proteins of

blood plasma

The respiratory organs of the toad are the lungs, skin, and the lining of the mouth caulty. They all have moist surfaces (epithelium) close over blood vessels. Oxygen from the air dissolves in the surface moisture and diffuses inward to the blood, whereas carbon dioxide passes in the opposite direction.. The hemoglobin in red blood cells combines with oxygen where plentiful and releases it as the blood passes through body tissues where oxygen is scarcer and needed. The hemoglobin enables the blood to transport much more oxygen than if the btter were dissolved in the plasma. Carbon dioxWe, however, is carried mainly by the pbsma.

Amphibians have more means of respiration than any other animal group, reflecting the transition from aquatic to tend habitats. In different species the gills, lungs, skin and buccopharynx serve separately or in combination. Amphibians are the lowest vertebrates with lungs (except for the dipnoan fishes).

Some waste is disposed of by the skin and lungs, others are discharged from the liver in the bile, and some are excreted from the intestines with the feces. The principal efrcretory organs of the frog are the two long brown kidneys dorsal to the coelom and peritoneum. The kidneys are selective filters that remove soluble organic wastes (especially urea), excess mineral salts, and water gathered from the body cells and fluids by the blood. The liquid waste collected in the kWneys is the urine. It passes down the ureters to the cloaca and may be \,voided at once through the anus or may be stored temporarily in the thin-walled bbdder connected to the ventral side of the cloaca. The daily output of urine in summer amounts to about 1/3 of the toad's weight.

THE HEAD, THORAK AND ABDOMEN ARE DISTINCT

The short winged, or lubber, grasshopper ingests and its food through its mouth, and digestion occurs in the stomach. The mouth parts surrounds:the mouth cavity, which opens into a slender muscubr pharynu that widens in a short esophagus joining to the large thin-walled crop. Below the crop is a small proventriculus or gizzard, lined by plates. The preceding parts comprise the fore-gut. Next is the midgut, or stomach (ventriculus), joined by a series of six double finger-shaped glandular gastrit caeca The hind-gut, or Intestine consists of a tapered anterior part, slender middle portion, and enlarged rectum that opens at the anus. Food is held by the forelegs, Icbrum, and bblum, lubricated by the salivary excretion (which contains some enzymes). and chewed by the mandibles and maxillae; the palps bear organs of taste. Chewed food is stored in the crop, further reduced in the gizzard, and strained into the stomach. There it is digested by enzymes, secreted by the gastric caeca and absorbed. In the rectum,

excess water is withdrawn from the undigested material which is formed into slender fecal pellets and

passed out the anus.

The slender tububr heat lies against the dorsal wall of the abdomen in a shallow pericardial cavity formed by the delicate transverse diaphragm. Blood enters the heart through pairs of minute lateral openings a oatia, with valves, and is pumped forward by contractions of the heart into a dorsal aorta extending to the head. There it emerges into the body spaces or hemocoel, between the internal organs, and moves slowly backwad around these organs, finally returning to the pericardbl sinus. Some blood circulates in the appendages and wing veins. (The hind wings are broad and membranous, with many veins, and fold under the forewings at rest. Each wing develops as a sac-like projection of the body covering and flattens to the thin membrane that encloses tracheae, nerves, and blood sinuses. The cuticle thickens along the sinuses to form strengthening nervures, or veins. When of full size, the wings become hard and dry but blood flow continues in some veins. The wing veins are of such constant pattern in species and higher group of insects as to be useful in classification) The system is an open, or lucunar, circulatory system and there are no capillaries or veins. The clear plasma contains colorless blood cells that act as phagocytes to remove foreign organisms. The blood serves mainly to transport food and wastes, as there is a separate respiratory system.

The paired spiracles connect to a system of ebstic ectodermal air tubes, or tracheae, that branches to all parts of the body. The finest branches, or tracheoles, carry oxygen (02) to remove carbon dioxide (C02) from the tissue cells. The grasshopper, unlike some insects, has several brge thin-walled air sacs in the aWomen, where alternate contraction and relaxation of the body wall serve to pump air in and out of the tracheal system.

To the anterior end of the hind-gut are joined a number of thread-like Malpighian tubules; these lie in the hemocoel and have their free ends closed. The tubule wall is composed of a single layer of large cells that remove urea, urates, and saHs from the blood and discharge into the intestines.

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WORKS CITED

BIOLOGY (Fourth Edition), Neil A. Campbell University Of California, Riverside General Zoology (Fourth Edition), Storer and Usinger McGraw-Hill Book Company http://biodiversity.uno.edu (BiodiversHy Collection) http://www.oit.itd. umich.edu/Biol 08 (Animal Diversity Web)