Question

Larva like stage of Hydra is
A. Hydrula
B. Hydra tuba
C. Scyphula
D. Planula

Answer 1

Hint: A larva is a larval form that many creatures go through before they mature into adults. Insects, amphibians, and cnidarians, for example, have a larval stage in their life cycle. The appearance of the larva differs significantly from that of the adult form (e.g. caterpillars and butterflies), with several distinct structures and organs that do not exist in the adult form.

Complete answer:
The Hydra's larvae are known as planulas. The cocoon splits into two pieces, each of which develops into a male gamete that the other Hydra releases into the sea. External fertilisation occurs, and the embryo develops into larvae.

A planula is a free-swimming, flattened, ciliated, bilaterally symmetric larval stage found in many cnidarian species including several Ctenophores. Some Nemertean species produce larvae that are quite similar to planula larvae.

The larva-like stage of Hydrozoan Cnidarians such as Hydra is known as a planula. These are open-water swims. The structure is flattened and bi-symmetrical. These have cilia bands that aid in swimming.

As a result, the correct response is option (D) 'Planula'.

In scyphozoans and some hydrozoans, the planula is formed from the fertilised egg of a medusa, while in anthozoans, it is formed from a polyp.
The planula either metamorphoses instantly into a free-swimming, tiny version of the mobile adult form, or it navigates through the water until it reaches a hard substrate (many may favour specific substrates), where it anchors and matures into a polyp, depending on the species. Many open-ocean scyphozoans are among the miniature-adult varieties. All planula-stage anthozoans, several coastal scyphozoans, and some hydrozoans are among the attaching types.

The planula is Aurelia's initial larval stage, developed shortly after the egg and sperm unite to form a zygote. The planula is lined with cilia and forms a scyphistoma when it settles. Many Cnidarians have larval stages of Planula.

Note:-
The planulae of the subphylum Medusozoa lack a mouth and a digestive tract, making them unable to feed themselves, whereas those of the subphylum Anthozoa can. The aboral end (the end opposite the mouth) of Planula larvae swims in front. Planula is a ciliated, bilaterally symmetrical, flattened, free-swimming larva of Cnidaria species. The free-swimming larvae of certain sponges are known as amphiblastula. Obelia isn't a sponge at all.