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

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

Phylum: Platyhelminthes flatworms most primitive animal that has/is... bilateral symmetry dorsal/ventral; anterior/posterior; left/right triploblastic endoderm- digestive system ectoderm- outer covering, nervous system mesoderm- muscle, excretory, reproductive systems tissue level of organization true organs believed to be first animal that could hunt for food; aided by bilateral symmetry and paired sense organs at the head acoelemate no body cavity (i.e. “solid body”) only internal cavity is the gut

Phylum: Platyhelminthes acoelemate no body cavity (i.e. “solid body”) only internal cavity is the gut

Phylum: Platyhelminthes no organized circulatory or respiratory systems thin,flat bodies allow diffusion of nutrients and gases centralized nervous system (cephalization) brain and sensory organs at head 2 nerve cords run length of body digestive system free-living planaria has branched one; single opening parasitic tapeworm has none reproductive system sexual- hermaphrodites both testes and ovaries, uterus in mesoderm layer cross- or self-fertilization asexual binary fission fragmentation and regeneration

Phylum: Platyhelminthes Class: Turbellaria free-living flatworms may have ciliate as ancestor size range from <1-60 cm 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

Phylum: Platyhelminthes Class: Turbellaria well-defined nervous system w/ sense organs ganglia concentrated as simple brain at head sensory cells (statocysts sense gravity, light sensory cells at eyespots, chemosensory cells) 2 nerve cords run length of body simple excretory system- protonephridia consists of flame cells (specialized ciliated cells) move fluid through branched ducts to outside via excretory pores maintains osmotic balance

Phylum: Platyhelminthes Class: Turbellaria digestive system (2-way system) branched w/ single opening serving as mouth/anus mouth, muscular pharynx, intestine digestion is extracellular and intracellular digestive enzymes secreted into digestive cavity small food particles enter ameboid cells by phagocytosis and digested in food vacuoles

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

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

Phylum: Platyhelminthes Class: Turbellaria 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 Class: Turbellaria Genus: Bdelloura commensalism with horseshoe crab attaches to gills or appendages of horseshoe crabs worm gets transportation, shelter, food scraps

Phylum: Platyhelminthes Classes: Cestoda, Trematoda ”The parasitic flatworms” most have 2 or more hosts during life cycle intermediate host- 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 contain unusual epidermis called tegument protects against detection/digestion by host some have microvilli to aid absorption of host nutrients some syncytial (cells have continuous cytoplasm) to aid in distribution of nutrients some secrete their own digestive/protective enzymes

Phylum: Platyhelminthes Class: Trematoda parasitic flukes live in intestine, liver, lungs, bladder and blood vessels involve at least 2 hosts 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 human disease schistosomiasis major world health problem common in Africa, Asia and South America chronic disease acute symptoms: fever, rash, body pains, cough, dysentery long term: can cause organ damage; rare lesions in central nervous system hosts- intermediate is aquatic snail definitive is human (or other vertebrates)

cercaria adult

Phylum: Platyhelminthes Class: Trematoda Genus: Schistosoma Life cycle stages: 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 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 that has sucker discs and hooks for anchoring to host

Phylum: Platyhelminthes Class: Cestoda long flat body made of many units called proglottids proglottid = complete reproductive unit with male and female gonads youngest proglottid behind head older proglottids w/ eggs shed in feces of definitive host reproductive output high many proglottids per tapeworm many eggs per proglottid

Beef tapeworm life cycle Phylum: Platyhelminthes Class: Cestoda Beef tapeworm life cycle

Phylum: Platyhelminthes Class: Cestoda Beef tapeworm life cycle (Taenia saginata) cattle ingest human feces with eggs and egg covering digested off to reveal larva with scolex that bores through intestinal wall to blood vessel to muscle larva grows in muscle to form a cyst called “bladder” human eats undercooked meat with “bladder” cyst digested open releasing tapeworm scolex attaches to intestinal wall and tapeworm grows, makes new eggs

Phylum: Platyhelminthes Class: Cestoda Pork tapeworm similar to beef tapeworm but pig is intermediate host can also develop bladders in human host can grow in eye or brain (interfere with vision or cause seizures Broad fish tapeworm (Diphyllobothrium latum) eggs reach freshwater to produce free swimming larva eaten by copepods (small crustaceans) copepods then eaten by fish humans can get by eating raw or undercooked fish absorb vitamin B-12 and can cause megaloblastic anemia

Platyhelminthes- The Table Symmetry- bilateral Segmentation- N/A Mesoderm present- yes, triploblastic Determinant cleavage Type of body cavity- acoelomate, “solid body”, lack body cavity other than digestive cavity Ciliated larva- trocophore-like in some (free-swimming, ciliated) Protostome- N/A; mouth=anus Nervous system- cerebral ganglia form simple brain, 2 nerve cords, specialized sensory cells Respiratory system- none, flat and thin for respiration by diffusion across cell membranes

Platyhelminthes- The Table Digestive system- Turbellaria has highly branched one but still 2-way (mouth=anus); Trematoda has some digestive tract; Cestoda has no digestive tract, absorbs food through external surface Excretory system- Excrete using ciliated flame cells that push wastes through excretory ducts and out excretory pores Reproductive system- contain testes and uterus; planaria are hermaphrodites; can reproduce by binary fission and fragmentation/regeneration

Platyhelminthes- The Table Circulatory system- none; relies on flat thin body for diffusion across cell membranes Members- Most are parasitic including Cestoda (tapeworms) and Trematoda (flukes). Turbellaria are free-moving and not parasitic.