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Marine Annelids: Class Polychaetes (Marine Worms) • Almost all marine annelids are polychaetes (class Polychaeta) are bilaterally symmetric, which are also known as “bristle worms” which is due to the translation from the Greek word polychaeta = with much hair. These bristles have many purposes, and branch out of their legs (referred to as parapodia). Home and Feeding • Many polychaetes live in temporary or permanent tubes – Singular – aggregations (groups) • Can be carnivorous or chemosynthetic organisms. • Tube-dwelling polychaetes can be are suspension feeders, trap and capture free floating scraps of food or plankton. • They use their “bristles” for capturing food and for gathering oxygen Most extreme worm on Earth! • One of the most remarkable polychates is the Pompeii worm • Found only at hydrothermal vents in the Pacific Ocean *Great example of a symbiotic relationship resulting in chemosynthesis (making food out of only chemicals like sulfur, nitrogen, carbon) – Temperatures as high as 80°C (176°F)! – “Fleece-like” covering of bacteria on their backs; the worms secrete mucus to feed the bacteria and in return, are protected by a degree of insulation on their backs Polychaetes are usually colorful! Christmas Tree Worm Free-living polychaete Advanced Life Forms! • Polychaetes have organs that sponges and cnidarians DON’T have such as: brain, hearts (yes plural), blood vessels, kidneys and an anus. • Each segment Can break off and Form a new worm! Marine worm reproduction - When ready to reproduce, they go through a process called epitoky which is the development of their gonads which become separated from the body of the worm and are called epitokes. When this happens, fertilization occurs externally. - Can be asexual by process similar to budding of jellyfish in which a small segment buds off and floats with other plankton, feeding and adding new layers are on their own. Interesting Facts • Some worms are not satisfied with plankton in their diet, so they resort to producing an acid which can decompose bones of fish and whales. The female worms are the only ones that do this, the males are microscopic and live within the female. • Then there’s Bobbit worms which can reach heights up to 10 feet. • https://www.youtube.com/watch?v=3H4J5QD QeA4