1500_11_Annelida - BIO1500 W07 Annelida or segmented worms...

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Unformatted text preview: BIO1500 W07 Annelida or segmented worms BIO1500 W07 Annelida or segmented worms Annelida basic facts !~13,000 species ! 0.5mm-3m !Majority marine, many terrestrial !Segmental body plan organization !Diverse feeding strategies (raptorial, saprophagous, filter feeding) !Lack of respiratory system Annelida represent a comparatively small animal phylum Mollusca Chordata Arthropoda Platyhelminthes Nematoda (?) Porifera Annelida Echinodermata Sarcomastigophora Apicomplex Ciliophora ~1,000,000 ANNELIDA: classification ANNELIDA: 1) Hirudinea: leeches (~500 Hirudinea: leeches species 2) Oligochaeta: earth worms 2) earth (~3000 species) 3) Polychaeta: marine worms 3) Polychaeta: (>10,000 species) Subphylum OLIGOCHAETA - eat soil, digest detritus+microbs - lack eyes - have fewer setae compared to polychaetes - lack parapodia. - although hermaphroditic, always reproduce by crossfertilization Subphylum HIRUDINEA Subphylum - most freshwater, few terrestrial and marine. - most predatory or scavengers. - NO setae. - NO parapodia. - reproduction: hermaphroditic with crossfertilization common (same as in earthworms). Subphylum POLYCHAETA http://weblog.greenpeace.org/defendingourmediterranean/images/180polychaete_worm_hermodice_caruncul ata__whole_worm_for_hibsy.html Subphylum POLYCHAETA Subphylum The polychaete Autolytus pachycerus from algal mats on rocks in the intertidal region at Bondi Beach. This animal buds off smaller individuals that fill with sperm or eggs and swim away to spawn with other 'epitokes'. http://www.ees.adelaide.edu.au/people/enviro/gregr/index.html Subphylum POLYCHAETA sabellid polychaete kh http://convoluta.ucdavis.edu/gallery/view_photo.php?set_albumName=Polychaetes_EVE_112&id=sabellid_poly chaete_kh Subphylum POLYCHAETA Planktonic Polychaete worm http://www.amonline.net.au/exhibitions/beyond/holoplankton/holoplankton05.htm Subphylum POLYCHAETA - eat sediment mud,organic detritus, microbes, planction or small invertebrates. - can possess eyespots or stalked eyes. - have many setae (small bristelike appendages occurring in pairs on Tentacle lateral and ventral sides). - each segment also caries a pair of Palp fleshy appendages called parapodia - Parapodia can facilitate crawling, burrowing or swimming and Setae enhance oxygen uptake - separate sexes, external fertilization. Jaw Eye Parapodium Subphylum POLYCHAETA Subphylum http://www.dnr.sc.gov/marine/sertc/gallery.htm Subphylum POLYCHAETA Phyllodocidae: raptorial feeding Several specimens of Phyllodoce novohollandiae attracted by a piece of dead mussel. Two of the animals have everted their muscular axial proboscis and are attempting to tear of pieces of the mussel. http://bugs.bio.usyd.edu.au/Polychaetes/phyllodoce_feeding.htm Subphylum POLYCHAETA Subphylum This movie shows an adult male polychaete (it is in a shallow tray with sea water). Platynereis dumerilii is a marine annelid (earthworms are also in this same phylum), and is one of many species of polychaete (segmented worms that build various tubes in which they mature to adulthood). We grow these polychaetes in trays of sea water. They feed upon protozoans that in turn feed upon lettuce (which we maintain in separate cultures and give to the worms on a regular schedule). Platynereis breeds according to a lunar cycle; we use artificial lighting to control spawning such that it occurs every two weeks.http://www.molbio.uoregon.edu/facres/labs/bowerman/movies.htm Subphylum POLYCHAETA Sabellida [feather duster worms]: filter feeders http://gump.auburn.edu/goertzen/SLuG/index.html http://bugs.bio.usyd.edu.au/Polychaetes/polychaete_feeding_modes.htm Subphylum POLYCHAETA Subphylum Sabellida [feather duster worms]: filter feeders http://www.dnr.sc.gov/marine/sertc/gallery.htm Subphylum POLYCHAETA Terebellidae: Selective deposit feeders Terebellid polychaete living in a burrow with palps extended for gathering food. Food particles are collected in the grooved palps which have cilia as well as mucus. The palps are drawn back to the mouth region where they are 'wiped clean' by the upper lip and ventral buccal organ. http://bugs.bio.usyd.edu.au/Polychaetes/terebe llid_feeding.htm Annelid key body plan traits Annelida are triploblastic animals Germ layer Ectoderm Ectoderm Mesoderm Mesoderm Endoderm Endoderm Developmental fate Epidermis, Nervous system Epidermis, Muscle, bone, gonads, circulatory system Muscle, Lining of digestive and respiratory system Lining Arthropods key bodyplan traits 2. Annelids are Protostomier Protostomier Protostome development Deuterostome development Annelids are eucoelomate Acoelomate animals possess mesoderm derived organs but no body cavity (Platyhelminthes). Pseudocoelomate species form open body cavities (Nematodes). Eucoelomate species have organs wrapped by coelom tissue generating an elaborate body cavity system (Annelids). Annelid key body plan traits 1. True segmentation Body subdivided in equivalent metameric units or segments. Each segment is equipped with the same set of excretory and locomotory organs. Pygidium Septa (“dividers”) Prostomium Peristomium segments Annelid key body plan traits 1. True segmentation Coelomic cavity Septal wall Septal wall Dorsal vessel Gut Longitudinal muscle Circular muscle Ventral vessel Nerve cord Nephrostome Nephridiopore Metanephridium Annelid key body plan traits 2. Some regionally modified segments Example earth worm (Lumbricus): Prostomium or cephalic region Peristomium Pygidium Pygidium Septa (“dividers”) Prostomium Peristomium segments Annelid organ systems 1. Muscular system uscular Circular, longitudinal and dorso-lateral muscles Epithelium Circular muscle Longitudinal muscle ”Herring Annelid organ systems 1. Muscular system uscular Circular, longitudinal and dorso-lateral muscles Longitudinal muscles parapodium setae Transverse muscles Annelid organ systems 1. Muscular system uscular Circular, longitudinal and dorso-lateral muscles Setal hair of earth worm species Musculature surrounding a oligochaete setal hair. http://biodidac.bio.uottawa.ca/thumbnails/filedet.htm?File_name=Olig020b&File_type=gif Annelid organ systems 2. Complete digestive system !Pharynx: ingestion of food !Esophagus: transport of food !Crop: food storage !Gizzard: crushing of food !Intestine: for absorbtion of nutrients Annelid organ systems 2. Complete digestive system Crop Esophagus Pharynx Gizzard Intestine Annelid organ systems 3. Central nervous system: 3. Cerebral ganglia as functional brain Ventral nerve cord (single chain of ventral ganglia). ventral Suprapharyngeal gangion Circumpharyngeal connectives Subpharyngeal ganglion Ventral nerve cord Annelid organ systems 3. Central nervous system: 3. Cerebral ganglia as functional brain Ventral nerve cord (single chain of ventral ganglia). ventral Ventral nerve cord in leech Ventral http://images.google.com/imgres?imgurl=http://ls.berkeley.edu/images/divisions/bio/gallery_mcb/leech-lg.jpg&imgrefurl=http://ls.b bnh=127&tbnw=83&ei=u9cHRo3sNIiEiQGeqNGTCg&prev=/images%3Fq%3Dleech%2Bcell%2Blineage%26svnum%3D10%26um%3D1%26hl Annelid organ systems 4) Closed circulatory system: Closed !Oligochaetes posses five lateral pulsating blood vessels serving as heart-like organs !Ventral and dorsal vessels along longitudinal body axis !Hemoglobin as respiratory pigment Annelid organ systems 5) Excretory system: Ciliated, funnel shaped nephridia Dorsal vessel Bladder Nephridiopore Nephrostome Ventral vessel Annelid organ systems overview http://instruct1.cit.cornell.edu/cou rses/biog105/labs/inverts/annelid a.html Annelid reproduction 1) Hirudinea (leeches) hermaphroditic 2) Oligochaeta (earth worms) 2) (earth 3) Polychaeta (marine worms): 3) Polychaeta bisexual Annelid reproduction Adult male and female polychaetes were placed in a small watch glass with seawater; the adults are about 30 or 40 mm long (one to two inches). The female swims in tight circles, while the male swims in larger circles that intersect with the female’ s circles. Watch for the male sperm appearing first, and then thousands of eggs! Pretty impressive, isn’t it? This results in the production of thousands of synchronously dividing embryos, and enables us to easily characterize large numbers of synchronously developing embryos. The embryos are about 100 microns in diamter and spherical. http://www.molbio.uoregon.edu/facres/labs/bowerman/movies.htm Annelid development proceeds through larval stage Growth zone Trochophore larva Segmented larva Adult Leech larva growth zone organization Annelid trochophora larva trochophore A - episphere B - hyposphere 1 - ganglia 2 - apical tuft 3 - prototroch 4 - metatroch 56 - anus 7 - protonephridia 8 - gastrointestinal tract 9 - buccal opening 10 - blastocoele The new superphylum Lophotrochozoa Raven Fig. 32.2 Lophotrochozoa: !Lophophorates !Platyhelminthes [flatworms] !Mollusca !Annelida… ...
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