1	Acoelomates - Phylum Platyhelminthes Bio 11 Avery
2	I. Platyhelminth diversity 20,000 known species, terrestrial, marine, parasitic 1mm to 30 cm long
3
4	II. Evolution and Systematics In Darwin’s younger days there were two recognized invertebrate phyla: Insecta and Vermes! A. Position in the animal kingdom (9-9, 14-28)
5
6	B. Evolutionary advances (Biological Contributions) Not terribly more complex than the cnidarians and ctenophores except 1. Bilateral symmetry 2. Cephalization 3. Ladder-like nervous system with ganglia 4. Triploblastic 5. Excretory system (protonephridia) 6. Increased complexity in musculature
7	C. Platyhelminth Classes 1. Turbellaria - free-living flatworms, mostly marine, cilia
8	2. Monogenea - mostly ectoparasitic flukes with only one host (aquatic animals), suckers reduced or absent
9	3. Trematoda - parasitic flukes with at least two hosts (first of which is usually a mollusk), tegument with one or more suckers
10	4. Cestoda - tapeworms, endoparasites, tegument, scolex and strobila of proglottids, no digestive tract
11	D. Other acoelomate phyla 1. Phylum Nemertea ribbon worms 20 cm to several meters! 650 species mostly marine 2. Phylum Gnathostomulida “little jaw-mouth” live in interstices of sand grains (marine)
12	III. Characteristics A. General 1. Parasitic or free living 2. Triploblastic, bilateral acoelomate and flat 3. Complex though incomplete gut (GVC)
13	"4." 4. Cephalized with cerebral ganglia 5. Protonephridia 6. Hermaphroditic
14	B. Unique Features
15	Platyhelminth body plans (draw) 14-8 a. Class Turbellaria - free-living flatworms
16	b. Class Trematoda - Flukes
17	c. Class Cestoda - Tapeworms
18	IV. Support A. Turbellaria - epidermis, bears cilia, secretes mucous (rhabdites) B. Cestoda, Trematoda - tegument a syncytial outer covering, no cilia C. Hydrostatic skeleton - all
19	V. Locomotion A. Cilia - Turbellaria only B. Muscle movement - all classes Circular - outer layer Longitudinal - inner C. Swimming larvae in Turbellaria and Trematoda D. How do Cestodes disperse?
20	VI. Feeding and Digestion A. Turbellaria Mouth, moveable pharynx, incomplete gut Extracellular digestion
21	VI. Feeding and Digestion A. Turbellaria Mouth, moveable pharynx, incomplete gut Extracellular digestion, phagocytosis, intracellular digestion B. Trematoda Mouth without moveable pharynx incomplete gut C. Cestoda No intestinal tract Absorption through tegument
22	VII. Circulation A. Diffusion keeps flatworms flat! Aided by branched gut and collecting protonephridial tubules B. True circulatory system in Nemerteans
23	VIII. Excretion and Osmoregulation A. Protonephridia (flame cells) B. System of tubules and pores C. Diffusion
24	IX. Nervous system A. Ventral, ladder-like B. Cephalized with cerebral ganglia
25	IX. Nervous system A. Ventral, ladder-like B. Cephalized with cerebral ganglia C. Ocelli (eyespots) present in some detect light, dark, movement D. Rheoreceptors - detect water movement E. Chemoreceptors throughout epidermis
26
27	X. Reproduction A. Asexual - fission B. Hermaphroditic (Monoecious) Internal cross-fertilize with other individuals C. Freshwater forms attach stalked eggs to undersurfaces of stones and plants embryos develop and emerge as young adults D. Others have ciliated larvae E. Parasitic forms have complex life histories
28	XI. Ecology - Turbellaria Glide along with head slightly raised in search of food mostly carnivorous
29	XI. Ecology - Trematoda Serious parasites in humans (see table 14-1) Know the Chlonorchis sinensis life cycle! 7 stages in the this typical fluke life cycle
30	XI. Ecology - Cestoda 4000 known tapeworms Know the Taeniarhynchus saginata life cycle!
31	Echinococcus granulosus Unilocular hydatid
32	XII. Summary