By Karly Kandel

Level of organization

Roundworms have organ-level of organiztion.

Germ layers

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.

Body cavity

They have a pseudoceolomate body cavity,that forms between the mesoderm and the endoderm.


No segmentaion.

Digestive system

Roundworm have a digestive system that runs the length of their bodies. It has a mouth, pharynx, intestine and anus, are also parasitic.

Circulatory system

No circulatory systerm.

Respiratory system

No respiratory system.

Excretory system

They have an anus at its rear end and a series of excretory tubes that end in an excretory pore.

Nervous system

Roundworms have a nervous system composed of anterior nervious tissue surrounding the pharynx that forms dorsal and ventral nerve cords that transmits impulses in the worm.


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.


Roundworms don't have a skeleton but have a cuticle that functions as support and a leverage point for movement for the worm.