WORMS

Phylum AnnelidaPhylum Annelida(Segmented Worms)(Segmented Worms)

•15,000 Annelid species15,000 Annelid species•Bilaterally symmetrical Bilaterally symmetrical coelomatescoelomates

–CoelomesCoelomes divided into partitions by divided into partitions by septasepta•Inhabit marine, fresh water, & moist Inhabit marine, fresh water, & moist environmentsenvironments•Has complex digestive systemHas complex digestive system•Has closed circulatory systemHas closed circulatory system•Epidermis is primary gas exchange organEpidermis is primary gas exchange organ•Are Are hermaphroditichermaphroditic•Reproduce sexually by Reproduce sexually by cross fertilizationcross fertilization•Reproduce asexually through Reproduce asexually through regenerationregeneration•3 Classes3 Classes

Class OligochaetaClass Oligochaeta• Include earthwormsInclude earthworms• Extracts nutrients from soilsExtracts nutrients from soils• Extremely beneficial to farming as they Extremely beneficial to farming as they enrich and aerate soilsenrich and aerate soils

The EarthwormThe Earthworm

Giant Earthworm – Amazon BasinGiant Earthworm – Amazon Basin

Class PolychaetaClass Polychaeta • Very similar to oligochaetaVery similar to oligochaeta• Most are marineMost are marine• Have paddle or ridge-like extensions Have paddle or ridge-like extensions on segments called on segments called parapodiaparapodia

• Aid in gas exchange and locomotionAid in gas exchange and locomotion

LugwormLugworm

Class Hirudinea (leeches)Class Hirudinea (leeches)• Most inhabit fresh Most inhabit fresh water, or moist water, or moist terrestrial terrestrial environmentsenvironments

• Feed on small Feed on small invertebrates or invertebrates or are parasiticare parasitic

• Have significant Have significant medicinal value in medicinal value in treating bruising, treating bruising, and as a source of and as a source of PharmaceuticalsPharmaceuticals

The LeechThe Leech

Phylum Nematoda:Phylum Nematoda:The Round WormsThe Round Worms

•Over 80000 speciesOver 80000 species•Cylindrical Cylindrical pseudocoeloematespseudocoeloemates•Have effective Have effective hydroskeletonhydroskeleton and and musculaturemusculature•Inhabit aquatic areas. Inhabit aquatic areas. Most are parasitic.Most are parasitic.•Most reproduce sexually. Most reproduce sexually. Females can produce ~100,000 Females can produce ~100,000 eggs a day.eggs a day.•Tricininella spiralisTricininella spiralis causes causes trichinosistrichinosis in humans in humans from under cooked porkfrom under cooked pork•Parasite burrows into Parasite burrows into muscle tissue forming cystsmuscle tissue forming cysts

•HookwormsHookworms andand pinwormspinworms can parasitize digestive can parasitize digestive systemssystems•Others cause Others cause heartwormheartworm andand elephantiasiselephantiasis

Parasitic Nematodes:Parasitic Nematodes:

RoundwormRoundworm HookwormHookworm

HeartwormsHeartworms

Guinea Worms:Guinea Worms:

Elephantiasis Elephantiasis (Filarial worm)(Filarial worm)

Life Cycle of Filarial WormLife Cycle of Filarial Worm

TrichinosisTrichinosis

Phylum NemertinaPhylum Nemertina• Similar to flat wormsSimilar to flat worms• Inclide proboscus wormsInclide proboscus worms• Acoelomate, but have functioning digestive tractAcoelomate, but have functioning digestive tract• Also have a funtioning blood vascular system Also have a funtioning blood vascular system

Phylum PlatyhelmenthesPhylum PlatyhelmenthesPlanarians, Flukes, & TapewormsPlanarians, Flukes, & Tapeworms

•Bilaterally Bilaterally symmetricalsymmetrical•Most flattened Most flattened "Dorsoventrally""Dorsoventrally"•Divided into 4 Divided into 4 classes:classes:•Simple acoeleomatesSimple acoeleomates

Class TurbellariaClass Turbellaria•Most free-living and non Most free-living and non parasiticparasitic•IncludeInclude planariansplanarians•Lack circulatory and gas-Lack circulatory and gas-exchange organs.exchange organs.•Simple excretory structures Simple excretory structures called called flame flame cellscells that that maintain osmotic balance.maintain osmotic balance.•Is Is cephalizedcephalized and has and has eye-eye-spotsspots which are sensitive to which are sensitive to lightlight•Feeds through ventral Feeds through ventral feeding tube called a feeding tube called a pharanxpharanx•Can reproduce sexually, or Can reproduce sexually, or asexually through asexually through regeneration regeneration

Planarian and assorted marine Planarian and assorted marine flatworms…flatworms…

Class Trematoda (Flukes)Class Trematoda (Flukes)• Similar in form to Similar in form to turbillariansturbillarians

• Many are parasitic. Many are parasitic. Example of Example of parasitic fluke is parasitic fluke is the the asian liver asian liver flukefluke

• Many have complex Many have complex life cycles life cycles including multiple including multiple hosts and hosts and alternation of alternation of generations.generations.

Life Cycle of the Liver FlukeLife Cycle of the Liver Fluke

Liver Flukes Cont’d…Liver Flukes Cont’d…

Liver Fluke encysted in a liverLiver Fluke encysted in a liver

Liver FlukeLiver Fluke

Class Cestoda (Tapeworms)Class Cestoda (Tapeworms)• Parasitic flatwormsParasitic flatworms• Can grow to enormous Can grow to enormous

lengths (up to 20m)lengths (up to 20m)• Parasitize mostly Parasitize mostly

vertebrate hostsvertebrate hosts• Attach head named Attach head named scolexscolex

to intestinal walls of to intestinal walls of host, and abosrb host's host, and abosrb host's nutrientsnutrients

• Following scolex is a Following scolex is a series of repeating series of repeating structural units called structural units called proglottidsproglottids

• Mature proglottids Mature proglottids containing thousands of containing thousands of eggs are released with eggs are released with the host's feces to the host's feces to infect other organisms.infect other organisms.

Tapeworms cont’d…Tapeworms cont’d…