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Phylum: Annelida • “ringed”, commonly called segmented worms • Examples: earthworms, marine worms, leeches Traits • Segmented, round, wormlike bodies Traits • Bilateral symmetry Traits • cephalized Traits • Ventral nerve cord Traits • Tube-in-a-tube digestive system with specialized regions Traits • Closed circulatory system – blood doesn’t leave the vessels Traits • Paired nephridia Traits • Respire through their skin Typical invertebrates • Earthworms are about halfway between the simplest and most complex invertebrates Classes Oligochaeta Polychaeta Hirudinea Oligochaeta • “few bristles”, no parapodia • E.g. – earthworms, tubifex worms Benefits of Earthworms • improves aeration • increases water and nutrient movement through the soil • Castings are rich in nutrients Usually feed on decaying organic matter – can eat ½ -1 times their weight • Charles Darwin went so far as to say of earthworms, “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures.” He believed that earthworms are wholly responsible for the top layer of rich soil on the Earth Earthworms vary in size from a centimeter to several meters long Giant Gippsland Earthworm in Australia Up to 15 feet stretched out! Blue luminescent earthworms in Australia • Striped earthworm in Australia just discovered in 2007 Worm Farming • Used for compost • Sold for fishing bait Tubifex Worms Polychaeta • “many bristles”, have parapodia, largest class of annelids • E.g. – marine worms, tube worms Parapodia • mainly used in respiration Blood worm Bristle worm Venomous Setae If touched, the setae will detach and lodge in the skin causing burning, itching, and numbness from the toxins they contain Tube Worms – make a tube for protection Marine worms Oligochaeta Polychaeta Hirudinea Hirudinea • No bristles or parapodia, have suckers • E.g. – leeches (blood suckers) Leeches are Ectoparasites Leach attacking a slug Leech Removal? • use your fingernail or something flat to break the seal of their suckers Irritating them can cause them to regurgitate their stomach contents in the wound, risking infection or disease Medicinal uses • Past – to suck out evil blood, to remove bruises Medicinal uses • Present – reattachment surgery, blood thinner • Leech saliva contains compounds that reduce pain, prevent clotting and dilate blood vessels. This prevents the tissue from dying off and allows the body to reestablish good blood flow to the reattached part. Summary: A 45-year-old, white male patient who suffered a complete avulsion of the upper two-thirds of his right ear. The ear was reattached by doing a microvascular anastomosis of a small artery anteriorly. No veins were available for anastomosis. Soon after anastomosis, there was obvious venous congestion. Medicinal leeches were used for treating venous congestion 48 Hours: 3 leeches have been applied every 8 hours. Following the initial application, obvious improvement was noted 24 Hours: Photograph shows severe venous congestion in the reimplanted ear following complete avulsion. 6 Days: The entire reimplanted ear was viable and healing well. 72 Hours: 3 leeches have been applied every 8 hours for periods of 15 to 30 minutes. Marked improvement in color with decreased swelling and congestion was noted. Two Months: Complete survival of reattached ear Also testing to be able to… • treat arthritis, blood clotting disorders, and varicose veins. Demi Moore Leech Therapy? http://www.youtub e.com/watch?v=bYe qPvv5s_E Giant Leeches Earthworm Structure Earthworm structure • Prostomuim – 1st segment, before mouth, contains lots of sensory nerves Earthworm structure • Clitellum – thick band around the worm, involved in reproduction Earthworm structure • Setae – little bristles that give the worm traction for movement Earthworm structure • Mouth – entrance to the digestive system Earthworm structure • Pharynx – (throat) sucks in food Earthworm structure • Esophagus – carries food from the pharynx to the crop Earthworm structure • Crop – stores food, lets worm eat a lot of food at one time and digest it later Earthworm structure • Gizzard – grinds the food Earthworm structure • Intestines – finishes digestion, absorbs food Earthworm structure • Anus – exit of the digestive system Earthworm structure • Aortic arches – 5 pairs (hearts), pump blood Earthworm structure • Dorsal blood vessel – carries blood away from the hearts Earthworm structure • Ventral blood vessel – carries blood back to the hearts Earthworm structure • Brain – coordinates and controls the body Earthworm structure • Ventral nerve cord – carries messages between the brain and the body Earthworm structure • Ganglia – bundles of nerves Earthworm structure • Seminal vesicles – store sperm Earthworm structure • Seminal receptacles – receive sperm from other worm Earthworm structure • Muscles – both longitudinal and circular – lets them lengthen and shorten their bodies Earthworm structure • Cuticle – non-cellular layer that protects the skin from gritty soil Earthworm structure • Nephridia – collect, concentrate, and eliminate wastes, don’t lose as much water Earthworm reproduction • hermaphrodites – exchange sperm • Night crawlers also mate on the surface. They are hermaphroditic but do not selffertilize. Following mating, each worm forms a tiny, lemon-shaped cocoon out of a liquid secreted from its clitellum. The sperm and egg cells are deposited inside the cocoon, and it is buried. After a two- to four-week gestation period, the baby worms emerge.