Give the order for the life cycle of the hydrozoan, Obelia, starting with the polyp form. Growth into mature polyp Cells grow into Planula. Reproductive polyps form. Medusa buds. Meiosis occurs. Fertilization occurs.

The correct order of the life cycle is Reproductive polyps form>>Medusa buds>>Meiosis occurs>>>Fertilization occurs>>Cells grow into Planula>>Growth into mature polyp

Explanation:

Reproduction in a colony of polyp is asexual. During such reproduction, the Obelia attaches to the surface of any substrate. Mature colonies have gastrozooids,  while the colonies have gonozooids which are called as  reproductive polyp and contains blastostyle and gonotheca.

When medusa released from gonozooids, they produce make medusae which swims freely and have velum with gonads, a mouth and tentacles. Here, sexual reproduction takes place, where the egg and sperm are released after meiosis and later they are fertilized to form zygote.

Zygote changes to blastula, blastula transforms into a swimming larva with cilia called as planula. After some time, when planula attaches to a solid surface, and transforms into a feeding polyp.

Later, the development polyps grow and produce branches and produce a new polyp thorough asexual budding.

The order for the life cycle of the hydrozoan is:

Reproductive polyps form>>Medusa buds>>Meiosis occurs>>>Fertilization occurs>>Cells grow into Planula>>Growth into mature polyp

starting with the polyp form→ Medusa buds.→.Reproductive polyps form.→ Meiosis occurs→  Fertilization occurs→Cells grow into Planula→Growth into mature polyp.

Explanation:

The life cycle of  Obelia alternate between polyp and medusa generations, with obelia the  most prominent.

Through asexual reproduction, mature polyps produces medusa body forms.The medusae grows and  budded off from the parents, they swim away from the parent  tissues  and this  aided  their dispersal.

Each of these  medusae may be male or  females, water is the medium of fertilization, and the sperm and egg produced,fertilized  to produce the zygote immature  larva called Planula. The planula swims with cilia  to attach to a substrate and later developed to mature polyp.

Through asexual means a single polyp medusa forms  a colony. The polyp again budded into medusa buds, medusae develops,  male and females, planula develops. mature polyps and the life-cycle continues again