Define Cercaria Larva?

Cercaria  larva is the fourth  larval stage  in  the life-cycle of F, hepatica. It is a free living stage produced  by  the  redia  larva.

1. It has a flat and oval body about 35 mm in  length and  a long  tadpole like tail.

2. Cercaria moves by muscular undulations of the tail.

3. Cercaria has two suckers an anterior, oral sucker surrounding the mouth and a ventral sucker situated in  the middle of the body.

4. Body space is filled with parenchyma and contains a few cystogenous glands on each side which  form tile cyst of the future larva.

5. The alimentary canal consists of mouth, muscular pharynx, oesophagus  and bifurcated and inverted Y-shaped intestine.

6. It also possesses an excretory bladder with a pair of protonephridial canals and a number of flame cells.

7. Cercaria also has two large non-functional penetration glands as well as rudiments  of  reproductive organs which have originated from germ cells.

8. Cercaria is a young fluke of sexual generation.

9. Cercaria  larva first comes out of the redia through its birth pore and  then also from the bogy of its snail host.