Transcript Nemertea
Nemertea Ribbon Worms Development • Bilateral Symmetry • Three Germ Layers • Acoelomate (coelom in proboscis) • Radial and Indeterminate body development • Characteristics • • • • • • • Live in a Marine Environment Dioecious (2 sexes) Nervous System and Brain Closed Circulatory System Proboscis apparatus Complete digestive tract Carnivorous Examples and Stories • Lineus longissimus 30M long and a few mm wide • Reports of 60M • Basiodiscus mexicanus (at right) • Archisymplectes (only fossilized Nemertean) • Gorgonorhynchus repens (50mm long) Lophophorate Development • • • • Bilateral Acoelomate Three Germ Layers Radial division during development Characteristics • A lophophore is a band of cilliated tentacles surrounding the mouth • Lophophore are retractable into coelom like space Platyhelminthes By: Ben, Matt, and Haram Characteristics • Flatworms have bilateral symmetry. • They have no true body cavity except for the gut, and are classified as acoelmates. • Their organ systems are formed of ectoderm, endoderm, and mesoderm. Schistosoma Life Cycle • Parasitic flatworms cause schistosoma in humans. -Infection occurs when cercariae penetrate the skin while in the water. -The cercaria loses its tail becoming a schistosomule which moves through various tissues to the veins. -Adults mature in the in the veins surrounding the intestines or bladder, depending on the species. -Females release eggs which move from the veins to the lumen of the intestine or the bladder. The eggs are then passed from the body in the feces or urine. http://faculty.clintoncc.suny.edu/faculty/michael.gregory/fi les/Bio%20102/Bio%20102%20lectures/Animal%20Dive rsity/Protostomes/Lophotrochozoans/Lophotrochozoans. htm Trichinella Life Cycle More Characteristics • Flatworms move by waving hair on their skin to propel themselves forward. • They also move by contracting their muscles. • Flatworm reproduction is hermaphroditic- each individual produces eggs and sperm. • When two flatworms mate, they exchange sperm so both become fertilized. Specialized Tissues Flatworms have : • A sac body plan, meaning they have one opening that functions as both a mouth and an anus. • A pharynx, which extends form the underside of the flatworm and sucks up food through the mouth • Flame cells that are used for excretion. • Amazing regeneration capabilities. Specialized Features • Cephalization (consists of 2 brains called ganglia and nerve cords arranged in a ladderlike configuration). • Gastrovascular cavity functions similarly to that of Cnidaria • Planarians, in Class Turbellaria, have eyespots that determines the presence and intensity of light. • The head (scolex) of the flatworms have hooks and suckers which function as an anchor. Different Types of Flatworms • Free-living carnivorous planarians • Parasitic flukes that feed off the blood of other animals • Parasitic tapeworms that live inside the digestive tracts of other animals. Examples of Flatworms • Turbellaria (freeliving) • Planaria • Monogenea (parasitic) More Examples • Cestoda : parasitic tapeworms • Digenea Round worms They have bilateral symmetry, and radial symmetry Nematoda Rotifera They have a simple nervous system that includes a main ventral nerve cord and a smaller dorsal nerve cord They use diffusion to breathe They don’t have an circulatory system so the fluid in their body moves nutrients around They are the simplest group to have an complete digestive system They also have a three layer cuticle to keep the body from drying out Nematoda and Rotifera are Pseudocoelomates. This is when the body cavity is derived from the mesoderm. The tissues are only loosely bound so it is not as organized as an coelomate MOVEMENT They use hydrostatic skeleton which change liquid pressure in the body changing the bodies shape causing movement. They also use longitudinal muscles to move their bodies side to side REPRODUCTION Parthenogenesis is when the female can have a growth that separates into an offspring They also can reproduce sexually WHIP WORM C. ELEGANS AFRICAN SPIRAL NEMATODE PSAMMOMERMIS BANANA NEMATODE They are a major cause important diseases of plants, animals, and humans. Diseases including filariasis, ascariasis, and trichinosis Some live in food products such as beer and vinegar.