Round Worms Flat Worms and Annelids Andrew Sahr

Round Worms, Flat Worms and Annelids Andrew Sahr

Characteristics § Roundworms: § Nemathelminths phylum § Range from microscopic to as long as 3. 3 feet (1 meter). § Have a hard, sharp spear on their head, and some have bristles on the head § Protected by a flexible but strong, grooved body covering § A layer beneath this covering releases fluids that harden to form the covering § Bilaterally symmetrical

Cont. § The body has 3 tissue layers and a fluid-filled false body cavity, meaning the cavity is between the inner and middle layers rather than the middle layer and the outer layer, as it is in complex animals § Roundworms live in salt water, fresh water and the soil. § Many of them are harmful to man as they are parasites.

Roundworm Life Cycle § Starts as an egg in a feces of an animal § Another animal either eats that animal or the feces of that animal § Transfers into the animals own intestines § Molts into the lava § Larva migrates through the intestinal wall and into the lungs where its coughed up and swallowed once more § Once it returns to the larva it begins to mature as an adult.

Reproduction § Sexually § Most species have a separate male and female but some are hermaphroditic § Males are typically smaller § Females have ovaries for holding the egg § During the copulation, male protrudes one or more spicules out of the cloaca and insert them into genital pore of the female.

Reproduction Cont. § Amoeboid sperm cells are passed along the spicules into the female worm § Eggs can be either embryonated or unembryonated when passed by the female, which means that their fertilized eggs are not yet developed

Roundworms in our Area § Baylisascaris § Intestinal Raccoon roundworm § Effects animals, including humans § Mature in Raccoon intestine § Released eggs take 2 -3 weeks to become infective § When we ingest them from soil or water they hatch into larvae inside us § Travel through the body § Affect our organs and muscles

Characteristics cont. § Flatworms: also known as flukes § Bilaterally symmetrical § Body has 3 layers of tissues with organs and organelles § Body contains no internal cavity § Possesses a blind gut (i. e. it has a mouth but no anus) § Has Protonephridial excretory organs instead of an anus

Cont. § Reproduction is mostly sexual as hermaphrodites § Mostly feed on animals and other smaller life forms § Some occur in all major habitats, including many as parasites of other animals § Bilaterally symmetrical

Life Cycle of Flatworms § Start as an egg § Passed out in the feces of a bird § Eaten by Whelks § Inside the larvae hatches the eggs and multiplies by budding § Leave and invade cockles § Infected cockles are eaten by the birds in which the flukes mature and lay there eggs

Reproduction § A flat worm is reproduced when it splits In two § It will immediately form a new flatworm § Hermaphroditic § Each individual produces sperm and egg § When two flatworms mate, they exchange sperm so both become fertilized. § can also reproduce asexually by transverse fission

Reproduction Cont. § The body constricts at the midsection, and the posterior end grips a substrate § body rips apart § Each half grows replacements of the missing pieces to form two whole flatworms § if one of these flatworms is cut in half, each half will regenerate into two separate fullyfunctioning flatworms

Flatworms in Our Area § Heterobilharzia americanum § Waterborne flatworm § Parasite § Affects mostly dogs and raccoons § Sexually reproduces in the intestines § Eggs are laid in there so they can be carried out through feces

Characteristics cont. § Annelids: § § § § § Bilaterally symmetrical Body has more than two cell layers which are tissues and organs Body possesses a through gut with mouth and anus Has true closed circulatory system Has no true respiratory organs Lives in most environments Feed a wide range of material Reproduction normally sexual and gonochoristic or hermaphoditic Includes earthworms and leeches

Life Cycle of Annelids, The Earthworm § Hermaphrodites. § When two earthworms mate § § § They lie together and cover themselves in sticky mucus Pass sperm into each others bodies Sperm makes the egg in each body grow § A thick ring of slime forms around each worm's body and as the earthworm wriggles forward § the ring with eggs inside it slips off and is left on the ground § The ring closes at both ends and becomes a hard cocoon that protects the eggs.

Cont. § The eggs hatch after two weeks if the weather is warm § They can take up to three months to hatch when it is cold § Usually one or two earthworms hatch out of each egg § The young worms are about 12 millimeters long and light pink in color § Earthworms are able to mate when they are twelve months old.

Reproduction § Asexual § by dividing into two or more pieces or by budding off a new individual while the parent remains a complete organism § Some reproduce all asexually, while some reproduce sexually as well § Leeches have never been seen reproducing sexually

Annelids in Minnesota § Earthworms § All terrestrial earthworms are not native to Minnesota § 15 species have been identified so far § Glaciers would have killed any worms before the European settlements § First Earthworms probably arrived through soil and plants from Europe

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