PoriferaCnidaria Ctenophora Phoronida Ectoprocta Brachiopoda Echinodermata Chordata Platyhelminthes Mollusca Annelida Arthropoda Rotifera Nemertea Nematoda “ Radiata ” Deuterostomia Protostomia Bilateria Eumetazoa Metazoa Ancestral colonial flagellate Phylum: Platyhelminthes

Kingdom: Animalia Phylum: Platyhelminthes Class: Turbellaria Class: Trematoda Class: Cestoda free-living planaria parasitic tapeworms parasitic flukes

flatworms most primitive animal that has/is... bilateral symmetry dorsal/ventral; anterior/posterior; left/right triploblastic endoderm- forms digestive system ectoderm- forms outer covering, nervous system mesoderm- forms muscle, excretory, reproductive systems true organs several tissues function together as organ evolutionary step above Cnidarians Phylum: Platyhelminthes General information

the first hunter aided by... bilateral symmetry cephalization paired sense organs at the head acoelemate mesoderm present but no true body cavity (i.e. has a “solid body”) only internal cavity is the gut Phylum: Platyhelminthes

acoelemate no body cavity (i.e. “solid body”) Phylum: Platyhelminthes

circulatory & respiratory systems none thin, flat bodies allow diffusion of nutrients and gases nervous system centralized nervous system cephalization brain and sensory organs at head 2 nerve cords run length of body digestive system free-living planaria highly branched with single opening parasitic tapeworm none Phylum: Platyhelminthes

reproductive system sexual hermaphrodites testes & ovaries, uterus in mesoderm layer cross- or self-fertilization depending on species asexual binary fission fragmentation and regeneration Phylum: Platyhelminthes

Kingdom: Animalia Phylum: Platyhelminthes Class: Turbellaria Class: Trematoda Class: Cestoda free-living planaria parasitic tapeworms parasitic flukes

Phylum: Platyhelminthes Class: Turbellaria free-living flatworms may have ciliate as ancestor size range from <1-60 cm (FYI) locomotion layers of muscles cilia some have glands that secrete mucus to glide along most are carnivorous, scavengers habitat most marine or freshwater some on humid land

nervous system cerebral ganglia is simple brain sensory cells statocysts sense gravity light sensory cells at eyespots chemosensory cells in auricles 2 ventral nerve cords connected by transverse nerve cords run length of body protonephridia is simple excretory system flame cells are ciliated and move fluid through branched ducts to outside via excretory pores maintains osmotic balance Phylum: Platyhelminthes Class: Turbellaria auricle eyespot

digestive system branching provides high surface area for diffusion of nutrients 2-way digestive tract (mouth=anus) mouth, muscular pharynx, gastrovascular cavity, intestine digestion extracellular & intracellular digestive enzymes secreted into gastrovascular cavity small food particles enter ameboid cells by phagocytosis and digested in food vacuoles Phylum: Platyhelminthes Class: Turbellaria

Phylum: Platyhelminthes Class: Turbellaria Reproduction asexual by binary fission sexual- hermaphrodites cross-fertilization some mate by “penis-fencing” sperm injected in body wall fertilization & early development inside “mother” juveniles that resemble adult released

Phylum: Platyhelminthes Class: Turbellaria Overview of organ systems digestive nervous reproductive excretory

Phylum: Platyhelminthes Class: Turbellaria FYI Convoluta roscoffensis mutualistic relationship ingests photosynthetic flagellates flagellates lose flagella and cell wall and take up residence in worm gut as adult, worm no longer feeds and survives off of flagellates later in life, worm digests flagellates and all die

Phylum: Platyhelminthes Classes: Cestoda, Trematoda “The parasitic flatworms” most have 2 or more hosts during life cycle intermediate host(s)- juvenile stage definitive host- adult stage much of structure devoted to reproduction produce lots of offspring to make it to the next host do not survive long outside of host tegument- special epidermis protects against detection/digestion by host some w/ microvilli to aid absorption of host nutrients some secrete their own digestive/protective enzymes

Phylum: Platyhelminthes Class: Trematoda parasitic flukes live in intestine, liver, lungs, bladder and blood vessels reproduction asexual in early life stages sexual in adult stages producing large numbers of eggs stored in uterus

Phylum: Platyhelminthes Class: Trematoda Genus: Schistosoma causes chronic human disease schistosomiasis major world health problem common in Africa, Asia, South America acute symptoms fever, rash, body pains, cough, dysentery long term symptoms organ damage; lesions in CNS hosts- intermediate- aquatic snail definitive- human (or other vertebrates)

cercaria adult miracidia

Phylum: Platyhelminthes Class: Trematoda Genus: Schistosoma Life cycle stages: fertilized eggs hatch into miracidium (larval stage, swimming ciliate, can only live 24 hrs outside of host) miracidium enters snail and becomes sporocyst (loses cilia) sporocyst reproduces asexually to produce more sporocyst or redia redia becomes cercaria (swimming stage that resembles adult form) cercaria leaves first host and enters vertebrate host (release digestive enzymes to help bore through skin) once in host, cercaria migrates through blood to large intestine and becomes adult to produce/fertilize more eggs

Phylum: Platyhelminthes Class: Trematoda Chinese liver fluke Hosts: snail>fish>mammal (human) In definitive host... cysts digested in intestine releasing fluke fluke travels up bile duct to liver attaches with suckers and feeds on blood causes anemia and liver disease may block bile duct

Phylum: Platyhelminthes Class: Trematoda Liver flukes

Phylum: Platyhelminthes Class: Cestoda tapeworms parasitic as long as 100 feet most have at least 2 hosts no digestive system; nutrients absorbed from host scolex = specialized head w/ sucker discs & hooks for anchoring to host

long flat body made of many proglottids complete reproductive units male & female gonads conveyor belt-like youngest behind head oldest w/ eggs at end old ones shed in host feces reproductive output high Phylum: Platyhelminthes Class: Cestoda (tapeworms)

Beef tapeworm life cycle Phylum: Platyhelminthes Class: Cestoda

Phylum: Platyhelminthes Class: Cestoda Beef tapeworm life cycle cattle ingest human feces with eggs egg covering digested in cow’s stomach to release larva with scolex that bores through intestinal wall to blood vessel to muscle larva grows in muscle to form a cyst human eats undercooked meat with cysts cyst digested open releasing tapeworm worm attaches to intestinal wall via scolex and tapeworm grows, makes new eggs that are released in human feces

Phylum: Platyhelminthes Class: Cestoda Pork tapeworm similar to beef tapeworm but pig is intermediate host Broad fish tapeworm eggs released from definitive host reach freshwater to produce free swimming larva larva eaten by copepods (small crustaceans) copepods eaten by fish larva bore into fish muscle and form cysts humans get by eating raw/undercooked fish

Platyhelminthes- The Table Symmetry- bilateral Segmentation- N/A Mesoderm present- yes, triploblastic Determinant cleavage Type of body cavity- acoelomate, “solid body” Ciliated larva- trocophore-like in some (free-swimming, ciliated) Protostome- N/A; mouth=anus Nervous system- simple brain (ganglia) at head, 2 nerve cords run length of body, specialized sensory cells Respiratory system- none, flat, thin body for gas exchange by diffusion

Digestive system- Turbellaria-highly branched, 2-way Trematoda- has some Cestoda- none, absorbs food from host digestive tract via diffusion Excretory system- protonephridia: ciliated flame cells push wastes through excretory ducts & out excretory pores Reproductive system- have testes and uterus; planaria are hermaphrodites and reproduce sexually or asexually (binary fission or fragmentation/regeneration) Platyhelminthes- The Table

Circulatory system- none; flat, thin body allows gas exchange by simple diffusion Members- Most parasitic Cestoda (tapeworms) Trematoda (flukes) Turbellaria- free-living, non-parasitic Platyhelminthes- The Table