RoundwormsBelongs to Phylum:

Nematoda

RoundwormsRoundworms areare

EVERYWHEREEVERYWHERE!!!!•Roundworms are all around Roundworms are all around us.us.

•They vary in size from They vary in size from microscopic to a meter longmicroscopic to a meter long

•A single rotting apple can A single rotting apple can have as many as 90,000 have as many as 90,000 roundworms and a small roundworms and a small bucket of soil or pond water bucket of soil or pond water can have as many as 1 millioncan have as many as 1 million

Main Characteristics of Roundworms

•Unsegmented- meaning they have no distinguished body parts

•Simplest animal to have a digestive system with two openings-both an anus and a mouth

•Have a pseudocoleom-meaning their colon is not completely covered in mesoderm

Anatomy of a Roundworm• Simplest animals with a digestive system with two

openings – a mouth and an anus• Have several ganglia-groups of nerves-but lack a brain• Muscles run in strips along the length of the body walls• Breath and excrete their metabolic wastes through their

body walls

Pseudocoelomates

• Roundworms have a pseudocolon meaning that they have a colon that is not completely covered by mesoderm.

mesoderm

Roundworm infectionHeartworm

Guinea Worms - Break out of skin when mature

Ascaris Life Cycle

1.Adult worms live the intestines. Eggs are passed with the feces

2. Fertile eggs become infective after several weeks

3.Infective eggs are swallowed

4.the larvae hatch

5 invade the intestinal wall, and are carried through circulation to the lungs.

6.The larvae mature further in the lungs (10 to 14 days), penetrate the alveolar walls, ascend to the throat, and are swallowed.

7.reaching the small intestine, they develop into adult worms

Roundworm Reproduction

• Roundworms reproduce sexually

• Most species have separate male and female, though some are hermaphrodites

• Fertilization takes place inside the female

• She later then lays eggs, which turn to larvae, then to adult worms

Roundworm Egg

Affects on Human Life

• Though they are very numerous around the world, roundworms do not exert a lot of positive influence in the everyday lives of humans so they are easy to ignore

• parasitic roundworms are responsible for some terrible diseases

Heartworm

• Found in the tropics• Nearly ¼ of the

population are infected with hookworm

• The eggs hatch and develop outside the body of the host

• Burrow into un-protected skin (often the feet) and enter the blood stream

• Travel from the lungs up to the pharynx and are swallowed

• They dig into the intestinal wall and suck the blood of the host

• cause weakness and poor growth

Hookworm

HOOKWORMSHOOKWORMS

Trichinosis

• The larvae then travel through the blood stream until they find a tissue to burrow into

• The larvae form cysts inside the muscle tissue of the host and become inactive.

•The adult worms live and mate in the intestines•The females burrow into the intestinal wall and lay up to 1500 eggs•This “burrowing” causes Great Pain towards its host

CystCyst

WormWorm

LarvaeLarvae

• complete their life cycle when the muscle tissue is eaten

(only carnivores can be infected)

• Most common animals infected are rats and pigs

• People get this disease from eating not completely cooked rat or pork

RATS

PIGS

Filarial Worms• Found in tropics• Thread-like worms• Live in blood/lymph

vessels of birds and mammals

• Transmitted by mosquitoes

• Can block the vessels – causing elephantiasis (now rare)

Elephantiasis

Eye Worms

• Related to filarial worms

• Found in Africa• Infect humans and

baboons• Live in sub-cutaneous

tissues• Sometimes travel

across the eye