By Karly Kandel
Level of organization
Roundworms have organ-level of organiztion.
Roundworms have three main germ layers:ectoderm, mesoderm, and endoderm.
Flatworms have bilateral symmetry, will only have identical halves if you cut along the longitudinal axis
Roundworms have sense receptors and nerves concentrated at their anterior end.
They have a pseudoceolomate body cavity,that forms between the mesoderm and the endoderm.
Roundworm have a digestive system that runs the length of their bodies. It has a mouth, pharynx, intestine and anus, are also parasitic.
No circulatory systerm.
No respiratory system.
They have an anus at its rear end and a series of excretory tubes that end in an excretory pore.
A roundworm reproduces sexually.The male worms have sperm cells that are made in the testis and stored in the vas deferens. The female have an ovary, that holds eggs in an oviduct and then passes them to the uterus, where they are fertilized. When it is time to reproduce, the sperm cells pass through the spicule.