Round Worms

Aleena Sallot

Level of Organization

Roundworms have organ systems: Excretory, Digestive, and Reproductive systems.

Germ Layers

Roundworms have three germ layers: endoderm, mesoderm, and ectoderm.


A roundworm has bilateral symmetry


Roundworms have cephalization. They have a head and their body follows it.

Body Cavity

The round worm has a pseudocoel body cavity that holds the flattened gut and reproductive organs.


A roundworm has no segmentation.

Digestive System

A roundworm has a definite digestive system that runs the length of their bodies. It has a mouth, pharynx, intestine and anus. Many are parasites and live off other animals and plants.

Circulatory System

A roundworm has no heart or formal blood vessels.

Respiratory System

A roundworm has no formal respiratory system.

Excretory System

A roundworm has an anus at its rear end and a series of excretory tubes that end in an excretory pore.

Nervous System

A roundworm has two nerve cords that transmit impulses in the roundworm.


A roundworm reproduces sexually. The female has an ovary, holds eggs in an oviduct and then passes them to the uterus, where they are fertilized. The male has sperm cells are made in the testis and stored in the vas deferens. When it is time to reproduce, the sperm cells pass through the spicule. Eggs can be deposited in the soil once fertilized.


A roundworm has no skeleton, but they have muscles to move and hold their round shape.