Which one of the blood vessel may be considered as true heart in earthworm ?

What structures are enclosed by dorsal and ventral lines of Ascaris ?

In housefly. where is the pseudotrachea is formed?

Which of the following cells are found only in sponges?

Cockroach has ciruculatory system of:

 If the skin of earthworm becomes dry, it dies due to what?

Annelids are hermaphrodites except the members of the which class?

Starfish belongs to:

The mouth parts of cockroach are:

Which is the intermediate host in the life cycle of liver fluke?