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Porifera • With pores, sessile, asymetric, diploblastic • Cells- outer pinacoderm, middleamoebocytes and inner-choanocytes • Skeleton- spicules and spongin fibres • Water canal system • Eg: Sycon, Spongilla ( Fresh Water sponge), Euplectella ( Glass sponge) Phylum Cnidaria General Characteristics • They are radially symmetrical; oral end terminates in a mouth surrounded by tentacles. • They have 2 tissue layers • Outer layer of cells - the epidermis • Inner gastrodermis, which lines the gut cavity or gastrovascular cavity (gastrodermis secretes digestive juices into the gastrovascular cavity) • In between these tissue layers is a noncellular jelly-like material called mesoglea Cnidarian Body Plans Polyp form • Tubular body, with the mouth directed upward. • Around the mouth are a whorl of feeding tentacles. • Only have a small amount of mesoglea • Sessile Medusa form • Bell-shaped or umbrella shaped body, with the mouth is directed downward. • Small tentacles, directed downward. • Possess a large amount of mesoglea • Motile, move by weak contractions of body Nutrition • Cnidarians are carnivores with hydras and corals consuming plankton and some of the sea anenomes consuming small fishes • They use they tentacles to capture prey and direct it toward the mouth so that it can be digested in the gastrovascular cavity via secretions from gland cells (extracellular digestion); some food is phagocytized by special cells and digestion occurs intracellularly • The gastrovascular cavity exists as 1 opening for food intake and the elimination of waste • There is no system of internal transport, gas exchange or excretion; all these processes take place via diffusion - Alternation of generation - Mouth or hypotostome present Ctenophora: Comb jellies - diploblastic, tissue level organisation - An outer epidermis, mesoglea with amoebocytes, and - An inner gastrodermis - Colloblasts- on epidermis of tentacles- for prey capture - locomotion- cilia with comb plates for nutrition - Eg: Ctenoplana Hormephora Platyhelminthes: Flat worms - unsegmented, bilateral symmetry, triploblastic - Acoelomate, organ system level of organisation - Suckers and hooks for holding the intestine of host - Incomplete gun – only mouth present, no anus - Excretion- Flame cells - Regeneration capacity high in Planarians - Eg; Taenia solium, Fasciola hepatica NEMATHELMINTHES - Round worms / thread worms Bilateral symmetry, Triploblastic , pseudo coelomate Alimentary canal- complete with muscular pharynx No respiratory and circulatory system muscles- Circular and longitudinal Sex- seperates; male shorter than female Fertilisation – internal - Ascaris, Wuchereria, Ancylostoma ( Hook worm) Annilida : Annullus: little ring - Triploblastic, bilateral symmetry, coelomate Metamerism Muscles- longitudinal and circular Digestion – complete Excretion- nephridia; circulation- closed Some are bisexual Development- indirect through Trocophore larva Eg; Pheritima, Tubifex ( blood worm), Neries Arthropoda - Body – Head, thorax and abdomen Jointed appendages, antennae, eyes ( ommatidia) and statocysts Digestive system is complete Chitin ; undergoes Ecdysis/ moulting Respiration- Gills/ trachea/ Book lungs/ / Book Gills Excretion- Malphigian tubules/ nephridia Fertilisation- internal , oviparous Apis , Bombyx, Laccifer, Anopheles, culex, locusts, Limulus Mollusca ( soft body) • • • • • • Body- Head, Visceral mass , muscular foot Radula- rasping organ Body wall – with mantle- secretes shell Digestion – complete; excretion- nephridia Unisexual, external fertilisation, oviparous Indirect development- Veliger, trocophore and Golchidium larvae Echinodermata • Endoskeleton- calcarious plates with spines • larvae- bilateral sym and adults- radial sym • Water vascular system with tube feet, radial canals– excretion, circulation • High regeneration capacity • development- indirect: Plateus, bipinnaria and auricularia Hemichordata • • • • • • Body- Proboscis, collar and trunk proboscis- Ciliated for collecting food Mouth- between proboscis and collar Stomochord- similar to notochord Excretion- proboscis gland Reproduction- sexual, dev- indirect ( tornaria) Chordata • Protochordata • Includes tunicates ( urochordates) and Cephalochordates • Tunicates- notochord and nerve chord present only in larva • Cephalochordatesnerve chord and notochord persistant • Vertebrata • Notochord replaced by vertebral column • Respiration – gills/lungs • Circulation – closed • -Includes Agnatha and Gnathosomata