Question

Water current is maintained in Herdmania is
a. Rhythmic contractions of a tunic
b. Opening and closing of atrial and branchial apertures.
c. Contraction of incurrent siphon
d. Cilia bordering gill slits

Answer 1

Hint: Herdmania belongs to the phylum Chordata, family pyuria, and genus ascidian tunicates. Also known as sea squirt as it can squirt out water when they are eliminated from their watery home. It can also contract its body. Water current enters through the mouth and moves through the pharynx where food is picked up and comes out by atrial aperture.

Complete answer:
- Herdmania exhibits a sedentary lifestyle. It respires through the branchial sac.
- Water enters into the body from the branchial aperture or mouth and it moves through the pharynx where food is taken up.
- Water comes out by the atrial aperture.
- The water current of the Herdmania is maintained by the cilia bordering gill slits.
- Water enters into the mouth by incurrent siphon but has no role in maintaining the water current.
- Tunic gives shelter to the organisms.
- The body of herdmania has two protuberances atrial siphon and brachial siphon.
- The atrial siphon has an atrial aperture or mouth whereas the branchial siphon has a branchial aperture
- Water enters and leaves the body at these apertures but has no role in the maintenance of water current.

Hence, the correct answer is option (D).

Additional information:
- Herdmania feeding tunicate is found in marine habitats.
- It is mostly found in the gregarious form.
- The body structure of herdmania is flat purse-like, 6-13 cm length, and is brown in color.
- It has a complete digestive tract.
- Consists of two apertures i.e incurrent and excurrent aperture.

Note: In herdmania water, the current is maintained by the cilia surrounding the gills. Water current also plays an important role in the gaseous exchange. When herdmania gets disturbed it releases a jet of water by both of its apertures. It is hermaphrodite. Metamorphosis of larval stage or tadpole to become adult. The whole body is covered with tunic which is made up of cellulose like organic substance called tunicin.