Worms- Ch. 14,15, 16Phylum Platyhelminthes Link to video Link to video

Flatworms - General Information Symmetry: Bilateral Cephalization- head end concentrated with sense organs and nervous control Tripoblastic- has a middle germ layer (mesoderm) as well as ectoderm and endoderm Parasitic in nature Examples of Flatworms include: planaria, flukes, and tapeworms 4 Classes : Turbellaria(Planarians), Trematoda (Flukes), Monogenea and Cestoda(Tapeworms)

Class: Turbellaria - Body Form Ciliated epidermis Rod- shaped Rhabdites- swell and form a protective mucous sheath around the body Dual gland adhesive organs in the epidermis

Class Monogenea, Tremotoda, and Cestoda – Body form Parasitic Non-ciliated body covering Ciliated covering is lost once a host is contacted

Digestive System: Includes a mouth, pharynx, and an intestine GVC- Gastrovascular cavity present Mainly carnivorous – feed on small crustaceons, nematodes, rotifers, and insects Flatworms have a system called: protonephridia/ can be used for osmoregulation or excretion System is mainly osmoregulatory ( regulates the water inside and outside of the body) Flame Cells- cup shaped cell that has flagella extending out

Flame cells act like a kidney, filtering and removing waste materials Flame cells act like a kidney, filtering and removing waste materials. It is the simplest form of an excretory system.

Nervous System- Simple nervous system (found in turbellarians) – Subepidermal Nerve Plexus similar to the nerve net in cnidarians May also have one to five pairs on longitudinal nerve cords lying under the muscle layer Have ganglia and neurons SENSE ORGANS: Ocelli: light sensitive eyespots Tactile Cells -touch Chemoreceptive cells Statocysts for equilibrium Rheorecptors- sensing direction in water currents

Cerebral ganglion is the brain, organizing sensory-, motor- and inter- neurons.

Reproduction and regeneration: Reproduce both sexually and asexually (fission) same as budding like the hydra Almost all flatworms are monoecious Some have spiral determinate cleavage typical of protostomes

Class Turbellaria – extra information Often distinguished on the basis of the form of the gut ( present or absent? , simple or branched?, pattern of branching? ) Creeping forms that combine muscular with ciliary movements to move

Class Trematoda All parasitic flukes Leaflike in form Penetration glands / organs for adhesion to hosts like suckers and hooks Increased reproduction capacity Sense organs are poorly developed EX: Liver Fluke in Humans ( common in regions of east Asia, especially China, Southeast Asia, and Japan; also common in cats, dogs, and pigs.) Blood Fluke (causes schistosomiasis)

Life cycle of a fluke

Class Monogenea Are all parasites ( on fish, frogs, turtles, and one on the eye of a hippopotamus) Cause little damage to hosts Can be serious if many hosts are crowded together (farm- raised fish)

Class Cestoda- Tapeworms Long, flat bodies Has a scolex(for attachment to host)- has suckers/ tentacles for attachment , and proglottids ( linear series of reproductive units) No digestive system Well-developed muscles Excretory system is similar to other flatworms as well as nervous system No special sense organs No head

Examples of Cestoda : Beef Tapeworm, Pork Tapeworm, Fish tapeworm, Dog Tapeworm

Often called ribbon worms Phylum Nemertea Often called ribbon worms Long muscular proboscis Bilateral Triploblastic 1000 species; all marine Complete digestive system

Ribbon worm, using proboscis, swallowing prey.

Rotifera (rotifers) Free-living aquatic animals. Many attach to substrates with their “foot”. Pseudocoelomate Complete digestive system, excretory system and reproductive system all empty into cloacal bladder.

Acanthocephala Spiny-headed worms. Cylindrical, spined proboscis Parasitic Excretory system No digestive tract Dioecious

Annelids link

Ch. 17 P. Annelida Segmented Worms – Each segment contains similar components of all major organ systems Annuli- Circular Rings that give this phylum their name Setae- Chitinous bristles ( exception: leeches) Eww! Freshwater dwelling – Oligochaetes (Earthworms and Leeches)

Body Plan Two part head region - Prostomium and Peristomium Terminal portion: pygidium which contains an anus Each segment contains: 1) circulatory, 2) respiratory, 3) nervous, 4) Excretory 5) coelom Peritoneum lines the body wall of each compartment Hydrostatic Skeleton: coelom is filled with fluid

Triploblastic- 3 Germ Layers Coelom well developed Bilateral symmetry Nervous System: double ventral nerve cord, ganglia, Brain Sensory system: Tactile (touch) organs, taste buds, photoreceptor cells

Reproduction Methods Asexually by fission Can completely regenerate Sexually- Monoecious – having both male and female organs 2 Classes have Clitellum( region of body) which aids in sexual reproduction

3 Classes: 2) C. Hirundinida –Leeches 1) C. Oligochaeta 2) C. Hirundinida –Leeches 3) C. Polychaeta ( paraphyletic group) What does THAT mean? Groups 1 and 3 share a common feature: Reproductive structure called a clitellum

Environments: Marine, Freshwater, and Land (terrestrial)