The Annelida phylum is a large group of segmented worms that consist of over 17,000 species. These include eagworms, leeches, and earthworms. They are mostly found in marine environments in fresh water and much like the Platyhelminthes phylum they are bilaterally symmetrical. The Annelida phylum has two different ways to get rid of waste. Annelids with blood vessels use metanephridria and those without use protonephridria. Both of these systems use the same two-stage filtration process during which waste materials and fluids are extracted and then filtered again to consume left over re-usable substances while deposing of toxic and drained materials as urine. They are also highly relying on the tubular organs known as nephridia.
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Arenicola marina-
The urinary system in Arenicola marina disposes of it's waste products through the use of nephridia, long coiled tubes covered with cilia on the inside. During this process, blood and different fluids enter the nephridia as nutrients, water, and salts are released before the left over wastes are released through the nephridiopore.
The urinary system in Arenicola marina disposes of it's waste products through the use of nephridia, long coiled tubes covered with cilia on the inside. During this process, blood and different fluids enter the nephridia as nutrients, water, and salts are released before the left over wastes are released through the nephridiopore.
![Picture](/uploads/2/9/0/6/29068025/5038463.jpg?338)
Lumbricus terrestris (earthworms)-
The urinary system of the Lumbricus terrestris is a three-step process that relies on the organism’s tubular organs known as nephridia. It starts with filtration, which is when water and dissolved materials are filtered out of the ventral blood vessel into the body cavity and then into the funnel-like pores on the nephridia. The nephridia also connect to the openings in the integument and allow fluid from the tube to be released into the environment. While the fluids are in the tube, it undergoes absorption as some important substances are retrieved from the tube and brought back to the blood and secretion during which substances are carried from the blood or body fluid into the tube. It then disposes of the ammonia in the soil.
The urinary system of the Lumbricus terrestris is a three-step process that relies on the organism’s tubular organs known as nephridia. It starts with filtration, which is when water and dissolved materials are filtered out of the ventral blood vessel into the body cavity and then into the funnel-like pores on the nephridia. The nephridia also connect to the openings in the integument and allow fluid from the tube to be released into the environment. While the fluids are in the tube, it undergoes absorption as some important substances are retrieved from the tube and brought back to the blood and secretion during which substances are carried from the blood or body fluid into the tube. It then disposes of the ammonia in the soil.
![Picture](/uploads/2/9/0/6/29068025/6134240.jpg?204)
Nereis vexillosa-
The urinary system of Nereis Vexillosa relies on the nephridia as well and very similr to Lumbricus terrestris and Arenciola marina. In Nereis vexillosa all body segments except the first and last contain an individual pair of nephridia because members of the Nereis genus are errant Polychaetes, which means the anterior and posterior segments lack nephridia. Similar to all other organisms included in the Nereis genus, Nereis vexillosa contains longer nephridial tubes than other members of the Annelida phylum.
The urinary system of Nereis Vexillosa relies on the nephridia as well and very similr to Lumbricus terrestris and Arenciola marina. In Nereis vexillosa all body segments except the first and last contain an individual pair of nephridia because members of the Nereis genus are errant Polychaetes, which means the anterior and posterior segments lack nephridia. Similar to all other organisms included in the Nereis genus, Nereis vexillosa contains longer nephridial tubes than other members of the Annelida phylum.