Chapter 12 Chapter 12 Part 2Part 2

The WormsThe WormsPlatyhelminthes, Nematoda Platyhelminthes, Nematoda

& Annelida & Annelida

Phylum: PlatyhelminthesPhylum: Platyhelminthes Examples: Examples: FlatwormsFlatworms, , Planaria Planaria spsp., tapeworms and ., tapeworms and

blood flukesblood flukes AcoelomateAcoelomate, Invertebrate, Simplest critter w/ bilateral , Invertebrate, Simplest critter w/ bilateral

symmetrysymmetry Simplest critter w/ “cephalazation” (distinct head region) Simplest critter w/ “cephalazation” (distinct head region)

((anterior) anterior) and tail (and tail (posterior) posterior) regionsregions Most are aquaticMost are aquatic Free living & parasitic lifestyles Free living & parasitic lifestyles

28 foot long tapeworm!

FlatwormsFlatworms Free Living Example - PlanariansFree Living Example - Planarians

DorsoventrallyDorsoventrally flattened flattened Able to regenerateAble to regenerate Circulatory & Respiratory Circulatory & Respiratory – – diffusion w/ environment w/ environment Digestive system Digestive system - - Incomplete w/ mouth pharynx & w/ mouth pharynx &

Gastrovascular cavity (GVC) which consists of branching Gastrovascular cavity (GVC) which consists of branching intestineintestine

Excretory System Excretory System – – flame cells & excretory pores& excretory pores Nervous System Nervous System - - Includes: anterior Includes: anterior cerebral ganglia “brain”, “brain”,

longitudinal nerve cords, and some lateral nerves, light sensitive eye longitudinal nerve cords, and some lateral nerves, light sensitive eye spotsspots

Muscular System Muscular System – under epidermis,– under epidermis,

layer of layer of circular & longitudinal circular & longitudinal musclesmuscles ReproductionReproduction – –

Asexual – fission & regenerationAsexual – fission & regeneration Sexual – Sexual – hermaphroditichermaphroditic produce both eggs produce both eggs

& sperm& sperm

AKA : GVC

FlatwormsFlatworms Parasitic Examples – Tapeworms & Flukes Complex multi-host life cycles Can be over 30 feet long! Eggs/larvae found in uncooked fish & meats No digestive system – absorb nutrients directly

from host intestines Structure

Scolex - anterior head region w/ hooks & suckers used to attach to the host intestinal wall

Proglottids - Extending from the neck is a series of proglottids; contain the sex organs; each mature proglottid release thousands of fertilized eggs into the host’s digestive tract for elimination.

Phylum Nematoda:Phylum Nematoda: RoundwormsRoundworms – – AscarisAscaris sp sp., hookworms, pinworms., hookworms, pinworms PseudocoelomatesPseudocoelomates, , Bilateral symmetryBilateral symmetry Free living and parasitic: Aquatic- marine and Free living and parasitic: Aquatic- marine and

freshwater and terrestrialfreshwater and terrestrial May be the May be the most abundant animalsmost abundant animals on earth. on earth. A bucket of soil can contain > 1 million roundworms!!A bucket of soil can contain > 1 million roundworms!! Simplest invertebrate with complete digestive system Simplest invertebrate with complete digestive system

( 2 openings): ( 2 openings): mouthmouth and and anusanus present present Lack circulatory & respiratory systemsLack circulatory & respiratory systems Primitive excretory Primitive excretory cells excrete through porescells excrete through pores Muscular system w/ only Muscular system w/ only longitudinal muscleslongitudinal muscles & no & no

circular muscles cause worm to thrash back & forth. circular muscles cause worm to thrash back & forth. Require something to push against to move forward. Require something to push against to move forward.

Nervous system has main ventral nerve cordNervous system has main ventral nerve cord Reproduce sexually, first animals we have studied Reproduce sexually, first animals we have studied

w/ w/ separate male & female separate male & female animals.animals.

Phylum Phylum Annelida:Annelida: Segmented wormsSegmented worms- earthworms, - earthworms,

leeches, bloodworms, sandworms, leeches, bloodworms, sandworms, polycheate wormspolycheate worms

Bilateral symmetryBilateral symmetry CoelomateCoelomate – first animal we’ve – first animal we’ve

studied w/ a true coelumstudied w/ a true coelum Invertbrate, aquatic (freshwater & Invertbrate, aquatic (freshwater &

marine) & terrestrialmarine) & terrestrial From < 1mm to over 10 feet longFrom < 1mm to over 10 feet long Free living & parisitic Free living & parisitic Medical use of leeches – Medical use of leeches –

anticoagulant secreted after sucker anticoagulant secreted after sucker attaches stops blood from clotting. attaches stops blood from clotting.

Annelids – Annelids – Segmented Segmented WormsWorms DigestionDigestion: : CompleteComplete system: Mouth, pharynx, esophagus, crop, gizzard, system: Mouth, pharynx, esophagus, crop, gizzard,

stomach, intestine, anus (ding-a-ling!)stomach, intestine, anus (ding-a-ling!) RespirationRespiration: Aquatic annelids typically breath through : Aquatic annelids typically breath through gillsgills, whereas terrestrial , whereas terrestrial

annelids annelids diffusiondiffusion O2 and CO2 thru the skin O2 and CO2 thru the skin Internal Transport Internal Transport – The Circulation: – The Circulation: First critter w/ true circulatory systemFirst critter w/ true circulatory system. .

Closed circulation Closed circulation w/ dorsal & ventral blood vessels connected at each segment w/ w/ dorsal & ventral blood vessels connected at each segment w/ smaller vessels called “ring vessels”. Has 5 pairs of enlarged ring vessels called smaller vessels called “ring vessels”. Has 5 pairs of enlarged ring vessels called ““Aortic ArchesAortic Arches” which act as hearts to pump the blood.” which act as hearts to pump the blood.

Excretory systemExcretory system: : Nitrogenous wastes from cellular activities excreted thru Nitrogenous wastes from cellular activities excreted thru use of use of nephridianephridia, (small tubular structures located in each metamere., (small tubular structures located in each metamere.

Nervous system Nervous system is well developed w/ organized is well developed w/ organized dorsal brain dorsal brain extending extending ventrally to a ventrally to a ventral nerve cord ventral nerve cord which connects small nerves from each segment which connects small nerves from each segment (metamere)(metamere)

MovementMovement – – muscles in the annelid are of muscles in the annelid are of two types longitudinal and circulartwo types longitudinal and circular ReproductionReproduction – – most reproduce sexually, some w/ separate sexes and some most reproduce sexually, some w/ separate sexes and some

species have individuals w/ both male and female organs in the same animal – species have individuals w/ both male and female organs in the same animal – hermaphroditichermaphroditic..

External AnatomyExternal Anatomy 1. 1. Mouth Mouth – ingest food and materials into digestive system– ingest food and materials into digestive system 2. 2. Anus Anus – Undigested food and wastes leave the body– Undigested food and wastes leave the body 3. 3. Metamere Metamere – Segments of the earthworm– Segments of the earthworm 4. 4. Setae Setae – bristles found on ventral surface– bristles found on ventral surface 5. 5. Clitellum Clitellum – secretes mucus and egg sacs– secretes mucus and egg sacs

mouth

Distinct dorsal (dark Distinct dorsal (dark colored) & ventral (light colored) & ventral (light colored) areascolored) areas

Polycheate Worm

Internal Structures and FunctionInternal Structures and Function 1. Mouth (entrance) 1. Mouth (entrance) 11. 5 pairs)Aortic Arches (hearts) 11. 5 pairs)Aortic Arches (hearts) 2. Pharynx (grabs food & pulls in) 12. Cerebral Ganglia (brain)2. Pharynx (grabs food & pulls in) 12. Cerebral Ganglia (brain) 3. Esophagus (passage way) 13. Dorsal blood vessel (vein)3. Esophagus (passage way) 13. Dorsal blood vessel (vein) 4. Crop (stores food) 14. Ventral Blood vessel (artery)4. Crop (stores food) 14. Ventral Blood vessel (artery) 5. Gizzard (grinds) 5. Gizzard (grinds) 15. Septa “snare drum” tissue 15. Septa “snare drum” tissue 6. Stomach (digests) 6. Stomach (digests) between metameres between metameres 7. Seminal Vesicles7. Seminal Vesicles 8. Intestine (digests)8. Intestine (digests) 9. Anus (eliminates) 9. Anus (eliminates) 10. Ventral Nerve 10. Ventral Nerve

CordCord

More worm diagramsMore worm diagrams

All done All done w/ w/

this worm stuffthis worm stuff