FLATWORMS Belong to the KINDGOM ANIMALIA PHYLUM PLATYHELMINTHES

Characteristics Three germ layers (endoderm, ectoderm, mesoderm) Bilateral symmetry Cephalization (has a head) 4. Acoelomates = without coelom COELOM = fluid filled body cavity

FORM AND FUNCTION FEEDING Free-living - carnivores or scavengers; they have a digestive cavity, mouth and pharynx Parasites – feed on blood, tissues or pieces of cells from within a HOST Most do not have a complete digestive system because they absorb material directly from host

Respiration, Circulation, and Excretion Thin bodies allow for materials to diffuse (respiration, excretion, etc) Flame Cell – specialized cells that remove excess water

Response Ganglia – group of nerve cells that control the body (like a brain) Eyespot – group of cells that can detect light (like an eye)

Movement Flatworms move in 2 ways Cilia helps them glide through the water Muscle cells help them twist and turn

Reproduction Sexual Reproduction – most flatworms are hermaphrodites (have both male and female sex organs) Asexual Reproduction by fission – flatworms can split in two and regenerate

Groups of Flatworms CLASS TURBELLARIA - free living flatworms - live in fresh or marine water - ex. Planarian

Planaria lives in freshwater, mostly a scavenger but can also feed on protists

Planarians are hermaphrodites They can also regenerate body parts and will sometimes split in half to reproduce (FISSION)

ANATOMY OF A PLANARIAN

Ganglia - planarian can process information about their environment Pharynx - used for suckling food in (the mouth is at the end of the pharynx) Eyespot - simple eye, can detect light Flame cells - located along the lateral edges, used for excretion

https://www.youtube.com/watch?v=GCNkbr6WBmQ

Class Trematoda = parasitic flatworms a.k.a “flukes” live in mouth, skin, or gills of host Primary host = the host in which a parasite reproduces sexually Intermediate host = the host in which asexual reproduction occurs

Schistosoma mansoni - multiple host: Primary host = human Intermediate host = snail Causes Schistosomiasis -in humans; decays lungs, liver, spleen, or intestines, occurs in tropical areas with poor sanitation/sewage.

https://www. youtube. com/watch https://www.youtube.com/watch?v=5wQbpgAdIMs&index=2&list=PLmhbae4HtQ-dxk6o91KN1KEw4t7OeVmpe

Class Cestoda =tapeworms Long, flat, parasitic Live in intestines

Scolex = a structure that contains suckers and/or hooks Proglottids = body segments of the tapeworm

Each mature proglottid is a hermaphrodite Testes produce sperm, fertilize the eggs to produce a zygote Zygotes are passed out through the feces.

Sometimes, a dormant, protective cyst is formed in the intermediate host muscles ****This is why you should never eat incompletely cooked meat.

https://www.youtube.com/watch?v=vnhFkZmRkw8

https://www.youtube.com/watch?v=KmGS-klEQHU