WORMS

KINGDOM - ...............

Worms range in size from microscopic parasites to the giant earthworm of Africa that may reach ........... Some live in soil, water, or inside living organisms. They are divided into 3 large groups:



PHYLUM - ...........................

Characteristics:

1. .......................................(Ectoderm, Mesoderm, Endoderm)

2. .........................................

3. Digestive systems with only one opening or less

Flatworms are divided into 3 classes:

CLASS ...........: Example (Planaria)

Planaria are small ( usually less than 1/2 inch), have a spade-shaped head, a body covered in cilia, and two eyespots that give the planarian its nickname, .................... They have no circulatory system or respiratory system. They absorb oxygen through their skin.

Nervous System: Planaria have a crude nervous system that consists of the two eyespots (only useful for detecting light), a small mass of nerve tissue that is called a ..................... instead of a brain, and 2 ........................ that are crossed by shorter transverse nerve cords.

Digestive System: The mouth is located on its ventral side, about halfway down the body. A slender ...................., a muscular feeding tube, sucks up food off the bottom of the pond or lake. Anterior and posterior digestive cavities inside the body digest and distribute food. Undigested food passes back out through the mouth.

................... located in the skin remove water and cell wastes.

Reproduction:

Asexual - .....................................

Sexual - Planaria are ...................................











CLASS .........................

Flukes are ................... Some are endoparasites (internal), some ectoparasites (external). Flukes usually have hooks or suckers which are used to attach to their host. Most endoparasites live inside the digestive system where they are protected from digestion by a thick coating called the ......................

Life Cycle of the ...............................

Adult flukes lay thousands of eggs in the intestines of sheep. The eggs pass out of the body with the .............. (solid waste) of the sheep. The eggs hatch out into tiny microscopic ............. that enter the bodies of a certain species of snail. After developing in the snail, they form .......... on the grass. After the cysts are eaten by sheep, they grow into adult flukes in the sheep's intestine.

Schistosomiasis

Blood fluke, genus schistosoma, infest more than .................. in the world. Tiny adults live in the blood where they may block blood vessels and cause internal bleeding.



CLASS - ..................

............... may grow up to 30 feet in length, live in the intestines of their host, and absorb digested food from the host. The head of the tapeworm is called a ................ It usually contains hooks or suckers. A tapeworm's body sections are called ................... They contain the reproductive system. Each proglottid is ................... and may self-fertilize or cross-fertilize. Each proglottid may contain 100,000 eggs. New proglottids form at the ................, behind the head, forcing the older sections to the posterior. Mature proglottids break off and pass out with the feces. The eggs may be eaten by cows where the larvae travel through the blood to the muscles and form cysts which are sometimes called ............. People may get tapeworms by ............................. that contains the cysts or by ingesting the eggs.



PHYLUM - .....................

................ usually have separate male and female sexes. They have longitudinal muscles that make them wiggle side to side. Most nematodes are ................. They may be plant or animal parasites. Nematodes may infect over ................ of the world's population. There are about 50 species of human parasites.

Well-known Nematodes:

.............................. lives in the intestines of humans, pigs, or horses. The female may reach 12 inches long and may lay 200,000 eggs a day. Their eggs may enter the body through infected food or water. The microscopic larvae hatch in the intestines where they bore into the walls and enter the bloodstream. From the blood they pass into the lungs where they are coughed up and swallowed back into the digestive system where they develop into mature adults and reproduce. Ascaris eggs can survive for as long as 5 years.



...................... get their name from a hook that they use to attach to their host's intestines. The microscopic larvae hatch in the soil and cling to the feet where they bore into the skin and blood vessels. Once in the blood they travel to the lungs, are coughed up and swallowed into the digestive system. Hookworms were once common in the south because of people going barefoot in the warmer climate and poor sewage disposal.

............................. causes a serious disease called trichinosis that is contracted by eating improperly cooked infected pork.

....................... are microscopic worms that are transmitted to dogs by mosquitoes. The adult worm burrows into the dog's heart where it can cause death.

..............................is found in Central Africa, India, and Pakistan. Its eggs and larvae are spread through the water. Larvae travel through the body and develop under the skin in moist areas of the body. Some may reach three feet long.

................- Filiarial worms live in the blood where they may block blood or lymph vessels causing a severe swelling called Elephantiasis. These are usually transmitted by mosquitoes.



PHYLUM -............ Annelid = ..............

Annelids have round, segmented bodies, with a true body cavity and advanced organ systems.



CLASS - Oligochaeta (..........)

.......... eat their way through the soil where they break up the clumps, aerate the soil, and add nutrients by breaking down the dead organic matter in the soil.

External View:

Covered in segments (100-150)

.......... - "upper lip" (flap that covers the mouth opening)

..........- the swollen area between segments 32-37. (Used for reproduction)

................ - small bristles found on each segment. Earthworms use .............. to anchor themselves in the dirt while they contract circular muscles and then longitudinal muscles.

Digestion:

The alimentary canal (the passageway through which the food passes) consists of :

Circulation:

Earthworms have a closed circulatory system (blood stays inside blood vessels at all times)

A ................... carries blood from tail to head. The ventral blood vessel carries blood from the head to the tail. Five pairs of tubes called ............. (sometimes called "hearts") connect the dorsal and ventral vessels and help pump the blood.

Click Here for diagram



Respiration & Excretion:

Earthworms absorb oxygen through their .......... and can suffocate if they dry out.

................. are tubes that carry liquid wastes from the cells to the skin. (have a similar function to ............).

Nervous System:

........................ - primitive brain

.................. - like our spinal cord except it goes down the belly

................. - swollen nerve centers on the nerve cord, one in each segment.

............... - special cells in the skin sensitive to light, sound, and chemicals

Reproduction:

Earthworms are hermaphroditic. ................... occurs when two worms exchange sperm Mucus from the ................ holds the two worms together during mating. ................ which store the worm's own sperm release their sperm which travel to the .................. of the other worm to be stored. Several days later the clitellum secretes a mucus capsule into which both eggs and sperm are deposited. The ............. seals and protects the eggs until hatching.

CLASS - ................. (Leeches)

Leeches are ectoparasites that feed on the blood of other animals. The anterior sucker of the leech has teeth that make the incision. The leech secretes an ............. called Hirudin to keep the blood from ............ This chemical can be used as a medicine.