Nereis virens, also known as clamworm or rag worm, is an animal that belongs to phylum Annelida and class polychaeta. They have tiny limbs around their body called parapods use for locomotive. N. virens are segmented and their body can consist of up to 200 segments. Their head contains eyes and antenna, which can be used as a detection system. Adult N. Virens is about 20 cm 40 cm’s long but one can reach up to 1 m long in length. Their habitat including muddy sand of coaster waters and estuaries. They are most common in Newfoundland to Virginia, in North America, Northern Europe, Norway, and Iceland to south of France. Due to their living environment, N. Virens experiences greater fluctuations in water salinity (Marine Species Identification Portal and Biology and UNT Biology Course 4506 2013).
Phascolopsis gouldii, a spiunculid worm, is an animal that belongs to phylum Sipuncular and class Sipunculidea. They are introvert animal, about one-third of the trunk length. P. gouldii are equipped with deciduous hooks that widely dispersed and arranged in ill-defined rings. They have many tentacle crown consists of many peripheral tentacles around the mouth. They have complex muscular system that compose of longitudinal muscle bands, circular muscles, retractor muscles, and spindle muscle that work together to support locomotion and feeding. Adult P. gouldii is about 5 to 10 cm’s long but one can reach up to 15 cm in length. Their habitat range from low tide line to shallow sub tidal depths. They are commonly found in Atlantic coast of North America from Florida to Nova Scotia. It is rare south of Long Island (Sipuncula LIfeDesk and Biology Course 4506 2013).
Fresh water organisms are hypertonic to their surrounding and is hyperosmotic regulators. They gain water by osmosis and produce copious urine to avoid excess of water in the. Furthermore, they lose ions urine and diffusion through the gills, but replace ions lost by active transport across the gills (Adolph 1925 and UNT Biology Course 4506 2013). There many experiments that demonstrate that among others, that marine forms will survived for various lengths of time in dilution of sea water. Their survival is made possible by the ability to adjust itself to external medium (Pearse 1928, Annandale 1922, Ferronierre 1901). Many marines’ animals are in osmotic equilibrium with their environment. Accordingly, if a marine organism is to put in a new environment of altered salinity, it must obtain a new equilibrium (Beth 1930). Nereis virens is an osmoregulation thus actively regulate its osmolality in order to maintain homeostasis. When transfer to freshwater will make N. virens increase in weight. However, N. virens decrease weight after the initial increase in about a day. Upon return to sea water from diluted water, N. virens lost weight rapidly (Leonard 1935). N. virens is an osmotic and ionic regulator. Phascolopsis gouldii is an osmoconformer thus always maintain the osmolarity of its body equal to the surrounding. Over the salinity range from about 45% saltwater to 160% saltwater, P. gouldii is an osmotic and ionic conformer (Larry 1982).
The purpose is to determine which animal is osmoregulator and which is osmoconformer by seeing how they react in a changing salinity solution. We will expose N. Virens and P. gouldii in four different solution of salt water and observe how their osmolality change with different salt concentrations. The concentration of the four salt waters are 100%, 80%, 60% and 40%. According to previous study done by Dr. Leonard and his team, N. virens is an ions and osmotic regulator that capable of obtain a new equilibrium when placing