Question

Connecting link between annelid and mollusk
A.Nautilus
B.Neopilina
C.Glochidium larva
D.Veliger larva

Answer 1

Hint: Mollusks possess a coelom, and a complete digestive system, and also specialized organs for excretion. Annelids had a coelom, a closed circulatory system, excretory system, and complete digestive system.

Complete answer:
Both mollusks and annelids most likely evolved from free living flatworms. Both flatworms and molluscs are triploblastic. Molluscs are generally aquatic, and are named from the Latin word molluscus which means soft. The soft bodies in them are enclosed in a hard shell made of calcium carbonate which perform the functions as an exoskeleton. This shell is secreted by a thin sheet of tissue known as the mantle which surrounds the internal organs like a glove. The mantle makes a small empty space called a mantle cavity which are then modified for different functions in different groups of molluscs.
Annelids are generally made of one or more body segments. Each segment is composed of one or more rings. These rings are called annuli. Annelids reproduce generally by sexual method by hermaphroditic cross fertilization. They can stimulate cut off pieces of their body. contrasting to sponges which are capable of coming back together if ripped apart. They had a hydrostatic skeleton a one way digestive system and they possessed bilateral symmetry.
Connecting link is the in-between form of organism between two types of organisms. Such an organism will have characters of both the groups . one of the main examples is Neopilina which is a connecting link between Annelida and Mollusca.

Hence, the correct answer is option (B)

Note: Neopilina is a connecting link between annelids and mollusc. The annelids characters present in them are metameric segmentation and presence of nephridia as excretory organs. And also the trochophore larva in life cycle. Occurrence of radula, shell and the mantle and molluscan type of circulatory system are their molluscan characters.