BIOL 2030 Lecture : [7] Platyhelminthes.docx

• School: York University
• Department: Biology
• Course: BIOL 2030
• Professor: Scott Kelly

Document Summary

Bilateral symmetry having two sides symmetrical about one median axis only, so that one side is a mirror image of the other. Planarian any member of the order tricladida, free-living flatworms (platyhelminths) living in streams, ponds, lakes, and the sea. They have a broad, flattened body, well- developed sense organs at the anterior end, and an intestine with three main branches. Rhabdite short, rod-like body in epidermal cell of turbellarians, which is discharged if the worm is injured and swells up to form a gelatinous covering. Pedal wave foot wave means of free-living flatworm movement. Protonephridum branching excretory duct of the protonephridial system ( excretory system in some simple invertebrates such as flatworms, nematodes, annelids, and rotifers. It consists of a system of branching ducts (protonephridia) each enclosed at its internal end by a flame cell, and opening into a central duct or to the surface through pores.