1. WORMS

2. WORMS Over 20,000 wormlike organisms Over 20,000 wormlike organisms Classified into 6-8 different phylum Classified into 6-8 different phylum All have bilateral symmetry All have bilateral symmetry Bodies have true tissues, organs and organ systems Bodies have true tissues, organs and organ systems Tissues derived from 3 germ layers: ecto, meso, and endoderm Tissues derived from 3 germ layers: ecto, meso, and endoderm We will be looking at the 3 most important worm phyla: flatworms, round worms, and segmented worms. (largest # of species and greatest impact on humans) We will be looking at the 3 most important worm phyla: flatworms, round worms, and segmented worms. (largest # of species and greatest impact on humans)

3. Phylum Platyhelminthes (Flatworms) Characteristics: Divided into 3 classes: turbellaria (free living flatworms; trematoda (flukes); and cestoda (tapeworms) Divided into 3 classes: turbellaria (free living flatworms; trematoda (flukes); and cestoda (tapeworms) Within the 3 classes approx. 10,000 species Within the 3 classes approx. 10,000 species Very flat, thin body Very flat, thin body Have a head Have a head Bilateral Symmetry Bilateral Symmetry Sensory organs in the anterior region (light/smell): they can detect food and move toward it. Sensory organs in the anterior region (light/smell): they can detect food and move toward it.

4. Flatworm characteristics cont… Have a brain, nerve cells (control center) Have a brain, nerve cells (control center) Most primitive organisms to show cephalization Most primitive organisms to show cephalization

6. Classes of Flatworms #1: Class Turbelaria – (Free living flatworms) Free living – those that are NOT parasites Free living – those that are NOT parasites Most common are planarians (fresh or salt water organisms) about 1 or 2 cm Most common are planarians (fresh or salt water organisms) about 1 or 2 cm Have a “blind” digestive system: mouth is the only entrance or exit. Have a “blind” digestive system: mouth is the only entrance or exit. Have a nervous system Have a nervous system Has two light-sensitive spots that resemble eyes on it’s head (they sense light and dark) Has two light-sensitive spots that resemble eyes on it’s head (they sense light and dark) Take in excess water by osmosis; and remove excess water by ciliated flame cells Take in excess water by osmosis; and remove excess water by ciliated flame cells Hermaphrodites – each individual produces male and female gametes (sperm from one worm fertilizes eggs of another worm) Hermaphrodites – each individual produces male and female gametes (sperm from one worm fertilizes eggs of another worm)

7. Planarians cont… Most are carnivorous (eat protists/small animals) which they trap in secretions from their mucous glands. Most are carnivorous (eat protists/small animals) which they trap in secretions from their mucous glands. They grasp its prey with its mouth and wrap their body around the prey They grasp its prey with its mouth and wrap their body around the prey The pharynx breaks food organisms into small pieces and pushes them into the gut. Food molecules are diffused from gut cells to the other body cells. The pharynx breaks food organisms into small pieces and pushes them into the gut. Food molecules are diffused from gut cells to the other body cells. Undigested food is expelled through the pharynx and the mouth. Undigested food is expelled through the pharynx and the mouth. Ability to regenerate Ability to regenerate

9. Class Trematoda: Flukes Parasitic flatworms Parasitic flatworms Organs and organ systems similar to planarians Organs and organ systems similar to planarians Outer layer has a tough, nonliving material called a cuticle that protects it from digestive enzymes of its host. Outer layer has a tough, nonliving material called a cuticle that protects it from digestive enzymes of its host. Have two suckerlike disks; one on the ventral surface & one around mouth Have two suckerlike disks; one on the ventral surface & one around mouth Suckers attach the worm to the host (host’s digestive tract) and it absorbs digested food from the host’s intestine Suckers attach the worm to the host (host’s digestive tract) and it absorbs digested food from the host’s intestine

10. Class Cestoda: Tapeworms All cestodes (tapeworms) are parasitic flatworms All cestodes (tapeworms) are parasitic flatworms Tapeworms are more specialized than flukes Tapeworms are more specialized than flukes Body is divided into many sections or proglottids (and it will continue to make more of these sections just behind its head) Body is divided into many sections or proglottids (and it will continue to make more of these sections just behind its head) Species vary in length and number of proglottids – some have thousands Species vary in length and number of proglottids – some have thousands No digestive system (they live in the intestine of a host No digestive system (they live in the intestine of a host Several human tapeworms are transmitted by infected pork, beef, or wild game that hasn’t been cooked Several human tapeworms are transmitted by infected pork, beef, or wild game that hasn’t been cooked http://www.youtube.com/watch?v=txSiApFzaZE

11. Tapeworm

12. Phylum Nematoda: Roundworms Round tubelike shape Round tubelike shape Extremely common (10,000 species) Extremely common (10,000 species) Small (less than a few mm in length) Small (less than a few mm in length) Soil and water Soil and water Most are harmless (except parasitic forms) Most are harmless (except parasitic forms) One way digestive tract (two openings); food enters the mouth and waste is expelled from an anus One way digestive tract (two openings); food enters the mouth and waste is expelled from an anus Have a body cavity that fills with fluid giving a round shape. – much like air in a tire; fluid also circulates material through the body Have a body cavity that fills with fluid giving a round shape. – much like air in a tire; fluid also circulates material through the body

13. Parasitic Nematodes Hookworm is a common roundworm parasite of humans Hookworm is a common roundworm parasite of humans Occurs where sanitation is poor and where human wastes are used as fertilizer, or where people are commonly barefoot Occurs where sanitation is poor and where human wastes are used as fertilizer, or where people are commonly barefoot Human waste from an infected person contain hookworm eggs. Eggs get in soil and develop into larval worms. Larval worms contact skin and pierce through and burrow in the body. Larvae is carried by the blood to different body parts. Adult worms attach to the intestine wall and feed on blood and tissue.(ex: sheep liver fluke) Human waste from an infected person contain hookworm eggs. Eggs get in soil and develop into larval worms. Larval worms contact skin and pierce through and burrow in the body. Larvae is carried by the blood to different body parts. Adult worms attach to the intestine wall and feed on blood and tissue.(ex: sheep liver fluke) http http://www.youtube.com/watch?v=GiHtUFuGgSA&feature=related

14. Hookworm

15. Hookworm Info. Affects 1 billion people worldwide Affects 1 billion people worldwide Commonly causes death in children because it increases their susceptibility to other diseases that could normally be tolerated Commonly causes death in children because it increases their susceptibility to other diseases that could normally be tolerated Very little chance of contracting it in the US or Canada due to our advances in sanitation and waste control Very little chance of contracting it in the US or Canada due to our advances in sanitation and waste control