1. preserved Nereis
The proboscis may be extended. It is divisible into an oral ring nearest the peristomium, bearing tiny, horny paragnaths, and the more distal maxillary ring, also bearing paragnaths and at its tip a pair of horny jaws. The extended, but not everted part of the gut opening at the jaws, is the pharynx. If the proboscis is not extended try to evert it yourself. Using a blunt object like the back end of your forceps, press on the segments about a centimeter posterior to the peristomium. If you've hit the right spot, you ought to be rewarded by seeing the eversible pharynx of the worm pop out of the mouth. You everted the pharynx more or less like the
worm does it by increasing the pressure of coelomic fluid in the surrounding segments, eventually pushing it out. How does the worm reinvert it?
2. differences in external anatomy/ morphology between Nereis sp. and Glycera sp.
3. descrive the flow of blood in the intact tentacles of Phragmatopoma and the nature of the circulation.
1. preserved Nereis
The proboscis may be extended. It is divisible into an oral ring nearest the peristomium, bearing tiny, horny paragnaths, and the more distal maxillary ring, also bearing paragnaths and at its tip a pair of horny jaws. The extended, but not everted part of the gut opening at the jaws, is the pharynx. If the proboscis is not extended try to evert it yourself. Using a blunt object like the back end of your forceps, press on the segments about a centimeter posterior to the peristomium. If you've hit the right spot, you ought to be rewarded by seeing the eversible pharynx of the worm pop out of the mouth. You everted the pharynx more or less like the
worm does it by increasing the pressure of coelomic fluid in the surrounding segments, eventually pushing it out. How does the worm reinvert it?
2. differences in external anatomy/ morphology between Nereis sp. and Glycera sp.
3. descrive the flow of blood in the intact tentacles of Phragmatopoma and the nature of the circulation.
