Question

Animal with free living larva but sedentary adult stage are
A. molluscs
B. sponges
C. star fishes
D. lobsters.

Answer 1

Hint: Pore bearing animals possess adult sedentary stage called as parenchymula and free living larval stage called as amphiblastula. Such pore bearing animals belongs to phylum porifera. They are simple types of organism which possess simple digestion and excretion through the canal system.

Complete answer:
Sponges belong to phylum porifera, which have simple body structure and possess a canal system. Sponges show free living larval stage known as amphiblastula and sedentary adult stage known as parenchymula.
A. Molluscs:- they are soft bodied animals they are mostly marine and some of the species of the molluscs bear calcareous shell to protect itself from the predators, and it is the second largest animal phylum, which show free living larval stage called trochophore and adult stage is also free living.
C. star fishes:- It is belongs to phylum Echinodermata, these all are marine in origin and live at the bottom of the sea or some other them are free living called pelagic , they usually bear spines, they possess both stage larval and adult stage is free living.
D. Lobster:- This animal species belongs to phylum arthropoda, those animal which bear jointed legs and appendages and this is the largest phylum of animal kingdom, body is divide into head, thorax and abdomen, they found in soil, water and as parasites on other animals body. They are free living which show metamorphosis and change into a free living adult stage.

So, the correct answer is B.

Note:
In sponges larval stage if free living which is free to move and reaches to the different place and attached to the substratum and starts to develop into adult stage which is sedentary in nature. Usually, three different body plans are found among sponges such as asconoid, syconoid, and leuconoid.