Essay On Herdmania

Herdmania is a marine, solitary and sedentary animal. It is fixed to rocky substratum by a flat base. Sometimes it attaches to the shell of chank as commensal. Chank carries Herdmania from one place to another where it gets abundance of food and oxygen. In return Herdmania conceals and protects chank from enemies as Herdmania is unpalatable. When it is disturbed, it suddenly contracts its body, and emits inner contents with force through its apertures. Hence it is commonly called as sea squirt. Herdmania is hermaphrodite and oviparous. Fertilization takes place in sea water. In Herdmania, the notochord appears only in the tail of the larva and disappears in the adults. Herdmania is a very common tunicate of Indian seas. It is widely used

*The soft body is covered by a test. *The test is transparent during young stage but in adult animal it becomes opaque due to increase in thickness. *It is pink in colour. *On the free side, body shows two projections, the branchial and atrial siphons (Fig.

Alimentary canal –The alimentary canal is coiled and complete tube like structure (Fig. 2.6).It comprises following parts – Mouth: - *Mouth (branchial aperture) is an opening in the branchial siphon. *It is guarded by four lobes or lips formed from the test. Buccal cavity –*Mouth opens into the cavity of branchial siphon, called buccal cavity or stomodaeum. * Base of the siphon has a strong branchial sphincter that regulates the opening of mouth. *At the base of the branchial siphon there are 64 tentacles of different sizes (Fig. 2.7) which are richly supplied with nerves that test the purity of water. *Each tentacle is soft, sickle shaped, curved and attached to the base of the siphon by its broad