Phylum Annelida Diagram Subphylum Classes Subclasses Unique Characteristics Characteristics Polychaete many bristles Parapodia Clitellata Clitellata Clitellata Oligochaeta few Hirudinoidea suckers fig 13 6 13 34 Chaetea 10 000 species parapodia Anterior sensory organs or tentacles on mouth or infront of Eversible pharynx With jaws Simple reproductive organs Occur segmentally Dioecious separate sexes trochophore larva No parapodia No antene or sensory structures Reduced or absent chaetae Hermaphroditic Complex reproductive system Clytelum covers eggs Clitellum cocoon Direct development 6 000 species Few chaetae Reduced cephalic structures Homonomous same not many diversity among segments Metaborism very strong Order Hirudinida 34 segments Anterior posterior suckers No chaetae Reduced coelom About 17 000 species the essence of being a protostome Live in all habitats if the habitat is moist enough can t dry out breath through skin Serial homology Results in metamerism Teloblastic development Schizocoely Complete GI Closed circulatory system Well developed nervous system dorsal cerebrail ganglion Metanephridia Segmental chaetae vessels Trochophore larva true coelom External Thin cuticle epidermis Anatomy Body Plans Regions Body Cavity Symmetry Fig 4 9 Pockets of mesoderm on anterior end A repeated process as body gets longer more and more segments are added Head presegmental prostomium before mouth peristomium around mouth stomium mouth cylindrical 13 2 Serial homology happens in these segmented body plan where most of the internal and external parts are repeated Metamerism body segmentation arises in a certain way results in teloblastic development Pygidium end of animal Post segmental and contains growth zone Forming body cavities as it goes replicates everything result in segments that are all serially homologous The proliferation of paired segmental mesodermal bands from teloblast cells at a posterior growth zone head prostomium peristomium prostomial palps sensory structures and antennae peristomial cirri Chatae setae Tiny spinelike form single epidermal cells Papapodium can be specialized biramous Has two branches 13 6 Top branch is notopodium dorsal And bottom branch is neuropodium ventral have separate sexes in mesodermal of body cavity Coelom muslces metameric plan parapodia Lack parapodia Fewer head appendages Fewer chaetae segmentally paired bundles Hermaphroditic Clitellum Important in reproduction 5 regions head parastoduim eyes mouth suckers region infront of clitellum ect 34 segments fixed with protomium dedicated Superficial annulations Anterior and poster suckers No chaetae no parapodia Reduced coelom to a series of interconnected spaces no segmentation Dorsoventrally flat Body Wall Segmentation Thin cuticle epidermis polychaetes Solid body connective Support Annuli coelomic compartments septa homonomous heteronomous each segment contains support system Each segment everything they need to function coelom segmentation closed circulatory system regionally specialized gut excretory structures alleviate constraints must be damp Locomotion Feeding Complete GI Connective tissue Within each segment circular longitidional muscles Within muscles have peritoneum Coelom fig 13 7 Laterally paired spaces serially arranged Lined with mesoderm Spaces are separated by mesenteries dorsal ventral Between segments are muscular septa Parapodia Part of body wall evagination muscular acicula chaetae can be retracted are supported Setae Cannot be moved Nereis undulations crawl 6 8 segments in one wavelength rapid crawl 14 segments in one wavelength swim 40 segments in one wavelength Errant move a lot Variations reflected in musculature septa parapodia ect Some use parapodia not many long muscles Raptorial grabbing hunting ambush Direct deposit digest organic material Complete septa Coelomic pores Help animal stay moist Are able to close off and not lose too much coelmoic fluid No parapodia tissue muscle coelomic channels support Cross section dramatically different Thick dermal connective tissue Reduced coelom Circular and long muscles and dorsoventral muscles No parapodia depend on peristalsis and chaetae Septa important Giant interneurons Can conduct action potential that much faster which can create an escape response all muscles will contract all longitudinal muscles Cannot move similarly segmented worm functionally a single internal space Do not burrow suckers impt inchworm motion also swimming Less diverse lack head appendages lack parapodia Predators pharynx impt Can be scavengers predators blood suckers Eat infrequently and gorge at one time Selective deposit and suspension sort sediment may have feeding tentacles that do sorting that may have ciliated grooves Chetphproous Animal Heteronomous U shaped burrow Segments 14 16 large notopodia create water current Neuropodia anchor Segment 12 creates a mucous bag moved by cilia to mouth and eaten done every 30 mins Forgut stomodeum buccal capsule pharynx anterior esophogus intestine with stomach Prctodeal rectum closed Cir System respiration over surface area parapodia repertory pigments dorsal vessel carries oxygenated blood anterior no pumping organs Segmentation requires that waste be removed from each segement Each segment 2 pr ducts coelomoduct gametes nephridioduct Circulatory System Closed circulatory system respitory pigments Digestive System Gas Exchange Excretion Detritivores sit on bottom of ponds to pull in water using muscles or ciliary forgut Direct deposit eg earthworm Hirudin anticoagulant Anesthetics vasodilators make the vessels larger Three blade like jaws 11th crop cecum is large are for storage of blood Crop muscular gizzard Typhlosole Chloragogen cells thought to absorb waste products 3 longitudional blood vessels dorsal is major Ventral below GI Subneural below nerve cord Body surface Can drown paired segmentally arranged metanephridia conserve water stay in moist envoirnment can make urea and actively transport salts can osmoconform Salivary glands Enlarged midgut stomach with ceca gut Flattened body cecal coelomic channels May have hemoglobin to help transport things ciliated funnels associated with circulatory vessels ciliated organs 13 25 nephridila capsule intercellular canal use urea gut wall uptake behavior protonophrida Most polychaetes have metanephridia ciliated nephrostome Nephrostome a merged coeloduct and nephridiaduct Protonophrida tends to be in closed capsule in acoelmates and blastocoelmates