Question

what are body cavity plans for non segmented worms?

Answer 1

Non segmented worms / rounded worm / Nematode  body contain mouth, reproductive organs and arse. Their body is rounded and elongated.

Coming to their morphology:

1. They have a cylinderical / filariform, unsegmented appendages and ends are pointed.

2. Their length are varies, the smallest length is less tham 5mm (Trichnella spiralis) and largest ones are about 1m (Dracunculus medinenis).

3. Their body consist of 3 layers

• The outer layer: It is know as cuticle,which are chemically complex and non-cellular. Some worms may contain the longitudinal ridges which is know as alae. Someother species the flap-like extension in the posterior end of cuticle caalled bursa.
• The middle layer: It is hypodermis which are cellular and thin. the dorsal, ventral and two lateral longitudinal cord are formed by the hypodermis. In these cord the nuclei of hypodermis is present.
• The inner layer: It is somatic muscular layer. This lies benath of hypodermis which is a single layer of smooth muscle cells.

4. The space between inner layer and viscera is body cavity. This body cavity consist of 2-6 cells fixed and body fluid.

5. The arse and mouth are present, so alimentry canal is complete. They have teeth or cuttings on the mouth. The food that pushed to oesophagus by the muscular struture. The shape of the oesophagus is varies from species. In the end of the arse, intestine is present which is tubular structure and have a single layer of columinar layer.

6. Their nervous system consist of sensory papillae, nerve ring and nerve trunk. And it is rudimentry.

7. They have a non developed excretory system. In some worms theiy have a pore in the mid-oesophagus area and excretory gland. Some other species have excretory system of H shaped complex tubular.

8. They are dioecious. They are seen in seperate sexes. The female is larger than the male. The male posterior end are coiled ventrally or curved. The male body consist of mouth, testes, seminal vesicle and spicule. The female body different from male by the presence of ovaries, uteri and hyponym.