Lophotrochozoans a clade identified by molecular data have

Lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms Trocophore larva Lophophore

Ecdysis: process of molting or sheading cuticle (exoskeleton) Cuticle is external, non living layer that protects the animal but can not grow with the animal. As the animal grows the old one is shed and a new one is secreted

Lab 37 Platyhelminthes and Nematoda

Phylum Platyhelminthes: flatworms

MAKE CONNECTIONS: Maximizing Surface Area Folding Flattening SA: 6 (3 cm× 3 cm) = 54 cm 2 V: 3 cm× 3 cm = 27 cm 3 1 µm SA: 2 (3 cm× 1 cm) + 2 (9 cm× 1 cm) + 2 (3 cm× 9 cm) = 78 cm 2 V: 1 cm× 3 cm× 9 cm = 27 cm 3 Diagrams comparing surface area (SA) for two different shapes with the same volume (V) Branching © 2017 Pearson Education, Inc. Projections Thylakoid

Phylum Platyhelminthes: flatworms • Flatten unsegemented body • Gut with one opening (absent in tapeworms) • Organ level of organization: nerve cords, protonephridia (excretory organs) , and gastrovascular cavity • Lack a Circulatory system and respiratory system • Lack body cavity • Beginning of a cephalization and light sensing organs

Class Turbellaria: free living flatworms • Skin is ciliated • Ventral opening to gastrovascular cavity with pharynx • Aquatic predators

Sketch each of the following: Planaria (live) dissecting scope label eye spots, auricle Planaria slide (student slide) COMPOUND scope Label Eyespot, auricle, gastrovascular cavity, pharynx,

Class Cestoidea: tapeworms • • Skin is not ciliated Parasites of vertebrates, in the digestive system Lack a mouth and digestive tract Anterior end with hooks and suckers (scolex) Body has repeating units (proglottids) Proglottid used in reproduction and dispersal Beef tapeworm (25 m) Pork tapeworm (Cysticercosis)

Observe the specimen on the jar of a tapeworm Taenia (group slide) COMPOUND scope - Sketch the scolex label hooks and sucker disc - Sketch a gravid proglottid

Class Trematoda: Flukes • • • Leaf like body Skin is not ciliated Oral and ventral suckers Parasites of vertebrates and snails Chinese Liver fluke, Sheep liver fluke Blood flukes How do people Get it? Schistosomiasis is the second most socioeconomically devastating parasitic disease after malaria

Observe the specimens of flukes in jars Sketch the following: Clonorchis, chinese liver fluke (student slide) label oral sucker, uterus, intestine, testes, mouth and pharynx

Phylum Nematoda: Roundworms - Cylindrical worms with unsegmented body - Body covered by a collagen cuticle (elastic but restricts growth), molted 4 times during growth - Body wall has only longitudinal muscles only - Found in virtually all habitats (poles, deserts, hot springs) - Handful of soil contains thousands of nematodes - Nematode parasites exist in nearly all animal and plant species

Free living roundworms In aquatic environments: they play a role in decomposition In soil environments: Predators of other nematodes and bacteria Important as food for mites, insects Vinegar eels Feed on bacteria and fungi found in nonpasteurized vinegar. They are raised by aquarists, who use them to feed newly hatched fish. C. elegans 1 mm long, living in soil environments

C. elegans as a model organism Multicellular and eukaryote, that is easily bred and can be frozen and thawed Entire genome sequenced Developmental fate of every cell determined Every neuron mapped It is proven useful in the study of cell death and Alzheimer's disease

Sketch : Live vinegar eel, compound microscope

Parasitic roudnworms In humans Hookworms: Pinworms: Most common worm parasite in the US but causes little disease

Parasitic roudnworms Ascaris lumbricoides is one of the largest and most common parasites found in humans. It is estimated that 25% of the world's population is infected with this nematode. In dogs and cats: Heartworms In Plants: Damage roots and transmit viruses (potato, soybean, grape vine)

Sketch one of the preserve specimens of Ascaris Sketch following: Ascaris cross section (student slide) FEMALE Cuticle, Pseudocoelome, uterus, muscles cells and intestine

End of chapter questions 2, 3, 5