Biology · Animal Kingdom · NEET
In direct development, the baby animal already looks like a tiny adult. It just grows bigger, with no larval stage. In indirect development, the egg first makes a larva. This larva looks very different from the adult. The larva then changes into the adult by a process called metamorphosis. So the simple test is: no larva = direct; larva present = indirect.
Metamorphosis is the change of a larva into an adult. During this change the body form is rebuilt, so the young stage and the adult stage look very different. For example, a tadpole (with a tail and gills, living in water) changes into a frog (with legs and lungs). Metamorphosis only happens in indirect development, because only indirect development has a larva to change.
Animals with direct development do not undergo metamorphosis, because they have no larval stage. NCERT and NEET use the earthworm (Pheretima, phylum Annelida) as the classic example — it hatches out looking like a small worm and just grows. Mammals also show direct development. Remember for NEET: earthworm = direct development = no metamorphosis.
Both frog and starfish show indirect development. The frog egg makes a tadpole larva that later becomes a frog. The starfish egg makes a bilaterally symmetrical larva that later becomes the radially symmetrical adult. Moths and tunicates also have larvae. So frog, starfish, moth and tunicate all undergo metamorphosis; earthworm does not.
The larva and adult often live in different places and eat different food, so their bodies are built differently. A caterpillar (larva) chews leaves; the moth (adult) flies and sips nectar. Because their jobs are so different, their body forms differ, and metamorphosis is needed to rebuild the body from larva to adult. This is why indirect development matters — the larva is a separate feeding and dispersal stage.
Ask one question: does this animal have a larval stage? Sponges, cnidarians, most flatworms, molluscs, echinoderms (starfish), many arthropods (moth, frog is a chordate but same logic) have larvae → indirect. Earthworm and mammals have no larva → direct. NCERT clearly states that in sponges 'development is indirect having a larval stage which is morphologically distinct from the adult.'
Which of the following animals does not undergo metamorphosis?
The unique mammalian characteristics are:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
No. It still has a young stage, but the young one already resembles a small adult. It simply grows into the adult without a larva and without metamorphosis.
They go together. Indirect development is the pathway (egg to larva to adult); metamorphosis is the specific change of the larva into the adult within that pathway. If development is indirect, metamorphosis occurs.
Sponges show indirect development. NCERT states their development is indirect with a larval stage that is morphologically distinct from the adult.
NEET regularly asks which animal does or does not undergo metamorphosis, and lists 'direct' or 'indirect development' as a feature in match-the-column and statement questions. Knowing earthworm and mammals are direct (no metamorphosis) versus starfish, moth and tunicate being indirect helps you score these easy marks quickly.
Yes. The starfish (Asterias) larva is bilaterally symmetrical while the adult is radially symmetrical — a favourite NEET point that also proves starfish has a larva and so undergoes indirect development.
