pseudocoelomates

THE PSEUDOCOELOMATES

THE PSEUDOCOELOMATES CONSIST OF NINE PHYLA OF ANIMALS WHICH HAVE A FALSE COELOM. THIS FALSE COELOM IS A SPACE WHICH DEVELOPS BETWEEN THE ENDODERM AND THE MESODERM. IT IS NOT LINED WITH THE MEMBRANE OF A TYPICAL COELOM, THE PERITONEUM, AND IS CONSIDERED TO BE A PSEUDOCOELOM, OR FALSE BODY CAVITY.

CHARACTERISTICS ü BILATERAL SYMMETRY, TRIPLOBLASTIC ü PSEUDOCOEL AS A BODY CAVITY ü MOST ARE VERY SMALL: SOME ARE MICROSCOPIC, A FEW A METER OR MORE IN LENGTH ü BODY IS VERMIFORM (WORMLIKE), AND CONTAINS MAINLY LONGITUDINAL MUSCLE FIBERS WITH A SYNCYTIAL CUTICLE ü DIGESTIVE SYSTEM IS COMPLETE (MOUTH, DIGESTIVE TUBE, ANUS) ü NO CIRCULATORY OR RESPIRATORY ORGANS ü EXCRETORY SYSTEM TYPICALLY PRESENT ü NERVOUS SYSTEM CONSISTING OF CEREBRAL GANGLIA OR A NERVE RING CONNECTING ANTERIOR AND POSTERIOR NERVES ü SENSE ORGANS CONSIST OF EYESPOTS IN SOME ORGANISMS, WITH OTHER SENSORY STRUCTURES SUCH AS BRISTLES IN OTHERS ü SEXES NEARLY ALWAYS SEPARATE (DIOECIOUS); THE MALE IS NORMALLY SMALLER THAN THE FEMALE

REPRESENTATIVE PSEUDOCOELOMATES

PHYLUM ROTIFERA PHYLUM NEMATODA—THE ROUNDWORMS v ABOUT 12,000 SPECIES HAVE BEEN NAMED, BUT IT HAS BEEN ESTIMATED THAT ABOUT 500,000 ACTUALLY EXIST v FREE-LIVING AND PARASITIC v LIVE ALL OVER THE WORLD—MARINE AND FRESHWATER, POLAR TO TROPICAL ENVIRONMENTS, ALSO ARE PLENTIFUL IN THE SOIL v MOST ARE LESS THAN 5 CM LONG; CAN BE AS LONG AS 1 METER v THE OUTER COVERING, OR CUTICLE, IS NONCELLULAR AND IS PRODUCED BY THE EPIDERMIS UNDERNEATH v THE CUTICLE HELPS TO RETAIN WATER AND CREATES HIGH HYDROSTATIC PRESSURE IN THE PSEUDOCOEL <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">v LONGITUDINAL MUSCLE FIBERS CAUSE THE WORMS TO MOVE IN A WHIPLIKE FASHION <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">v MOST ARE DIOECIOUS, WITH THE MALE SMALLER THAN THE FEMALE <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">v THE MALE POSSESSES A PAIR OF COPULATORY SPICULES WHICH HOLD OPEN THE FEMALE REPRODUCTIVE OPENING SO THAT SPERM CAN BE INSERTED
 * ABOUT 1800 SPECIES, MOSTLY FRESHWATER
 * MOST ARE LESS THAN ½ MM IN LENGTH
 * CHARACTERIZED BY A CILIATED CROWN, CALLED A CORONA, WHICH IS USED FOR LOCOMOTION AND FEEDING
 * THEIR MUSCULAR PHARYNX, OR MASTAX, IS CONSTANTLY IN MOTION GRINDING FOOD AND IS VERY DISTINCTIVE
 * SOME SPECIES CAN LAY EGGS THAT DEVELOP INTO ADULTS WITHOUT BEING FERTILIZED

EXAMPLES: 1. //Ascaris lumbricoides//, AN INTESTINAL ROUNDWORM <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">Ø ANTERIOR END HAS A HOOK <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">Ø //Necator americanus// IS THE MOST COMMON SPECIES <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">Ø HEAVY INFECTIONS CAUSE ANEMIA <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">Ø IN CHILDREN, MAY RESULT IN MENTAL RETARDATION AND STUNTED GROWTH, ALONG WITH A GENERAL LOSS OF ENERGY <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">Ø JUVENILES BURROW THROUGH THE SKIN OF THE HOST
 * ONE OF THE MOST COMMON PARASITES OF HUMANS; UP TO 64% INFESTATION OCCURS IN SOME AREAS OF THE SOUTHEASTERN UNITED STATES; UP TO A BILLION PEOPLE AFFECTED WORLDWIDE
 * FEMALES MAY LAY 200,000 EGGS A DAY
 * INFECTION USUALLY OCCURS WHEN EGGS ARE INGESTED WITH UNCOOKED VEGETABLES, OR WHEN CHILDREN PUT DIRTY FINGERS OR TOYS IN THEIR MOUTHS
 * 1) HOOKWORMS

<span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;"> //Trichinella spiralis// IS ONE OF MANY SPECIES WHICH CAUSE TRICHINOSIS, A POTENTIALLY LETHAL DISEASE IN HUMANS <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;"> ADULT WORMS PENETRATE THE INTESTINAL WALL TO REACH THE BLOOD VESSELS, WHERE THEY EVENTUALLY ARE CARRIED TO SKELETAL MUSCLE CELLS <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;"> HUMANS ARE TYPICALLY INFECTED BY EATING CONTAMINATED, UNDERCOOKED PORK <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;"> ABOUT 2.4% OF THE U.S. POPULATION IS INFECTED
 * 1) TRICHINA WORM

<span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">§ RELATIVELY HARMLESS, //Enterobius vermicularis// IS THE MOST COMMON PARASITE IN THE U.S., INFECTING ABOUT 30% OF CHILDREN AND 16% OF ADULTS <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">§ ADULT FEMALES LIVE IN THE LARGE INTESTINE AND MIGRATE TO THE ANUS AT NIGHT TO LAY THEIR EGGS <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">§ SCRATCHING CONTAMINATES HANDS AND BEDCLOTHES; SWALLOWING THE EGGS RESULTS IN RECONTAMINATION <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">ü AT LEAST 8 SPECIES INFECT HUMANS <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">ü //Wuchereria bancrofti// or //Brugia malayi// INFECT ABOUT 250 MILLION PEOPLE IN TROPICAL COUNTRIES <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">ü THE WORMS LIVE IN THE LYMPHATIC SYSTEM AND CAUSE INFLAMMATION AND SWELLING, KNOWN AS ELEPHANTIASIS, AFTER REPEATED EXPOSURE <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">ü MOSQUITOS TRANSMIT THE WORMS BY FEEDING ON INFECTED HUMANS <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">ü RIVER BLINDNESS IS TRANSMITTED BY THE BLACKFLY AND INFECTS MORE THAN 30 MILLION PEOPLE IN PARTS OF AFRICA, ARABIA, CENTRAL AMERICA, AND SOUTH AMERICA <span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; msolist: Ignore;">ü THE MOST COMMON FILARIAL WORM IS THE DOG HEARTWORM, //Dirofilaria immitis,// WHICH IS ALSO CARRIED BY MOSQUITOS
 * 1) PINWORMS
 * 1) FILARIAL WORMS

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