What is metagenesis describe the life history of Obelia?

METAGENESIS The life cycle of Obelia represents a remarkable example of alternation of generation where the asexual and sessile phase of Obelia reproduces asexually by budding and gives rise to sexual and free-swimming medusa. This phenomenon of alternation between two diploid phases is termed as metagenesis.

What is the kingdom of Obelia?

Animal
Obelia/Kingdom
Obelia belongs to the animal kingdom within the hydrozoa class and has many species. The list below outlines how the obelia is classified in biology: Kingdom – Animalia (animals) Phylum – Cnidaria (sea anemones, corals, jellyfishes, and other relatives)

What is the function of polyp of Obelia?

Polyp or hydranth (nutritive zooids): This nutritive zooid of the colony is also known as gastrozooids or trophozooid. It is yellow in color, radial symmetrical and cylindrical in shape. They are specialized for capture, ingestion and digestion of food. Each hydranth is closely similar in structure to that of hydra.

Where is Obelia found?

The medusa stage of Obelia species are common in coastal and offshore plankton around the world. Obelia are usually found no deeper than 200 metres (660 ft) from the water’s surface, growing in intertidal rock pools and at the extreme low water of spring tides.

What is the life cycle of Hydra?

Hydroids have three basic life-cycle stages: (1) a tiny free-swimming ciliated planula larva about 1 mm (0.04 inch) long, which settles and metamorphoses into (2) a sessile (attached), usually colonial polyp stage, which in turn liberates (3) a gamete-producing male or female medusa (“jellyfish”).

Where is obelia found?

What is the scientific name of Hydra?

Hydra
Hydra/Scientific names

How is Obelia Trimorphic?

In fact, to start with Obelia is a monomorphic form having polyp only but later due to the development of blastostyle it becomes a dimorphic colony and finally medusae bud over the blastostyle in a mature colony, then it becomes a trimorphic colony.

Why Obelia is called Trimorphic?

It is called trimorphic because it has 3 stages in its life and these are polyp medusa and blastostyle.

How can we identify Obelia?

[Obelia-medusa] Umbrella flat, with velum minute or lacking (authorities differ). Stomach short, with quadrangular base, without peduncle; mouth with four short simple lips. Radial canals four, straight; they and ring canal narrow, the latter hard to discern.

What is the life cycle of an Obelia?

In this article we will discuss about the life cycle of obelia, explained with the help of suitable diagrams. 1. It is a branched, fixed colony (Fig 20.12). Some of the horizontal branches anchoring the colony on some support are called Hydrorhiza while other branches are vertical and known as Hydrocaulus.

What is the structure of an Obelia colony?

1. It is the slide of obelia, which is a marine, colonial and arborescent animal. 2. It is found attached to submerged objects like rocks and weeds etc. 3. All the individuals in a colony are attached through branches to a horizontal hydrorhiza. The branches are called hydrocauli.

Which is the monomorphic form of the Obelia?

In fact, to start with Obelia is a monomorphic form having polyp only but later due to the development of blastostyle it becomes a dimorphic colony and finally medusae bud over the blastostyle in a mature colony, then it becomes a trimorphic colony.

What kind of root system does an Obelia have?

Each colony of Obelia consists of a horizontal thread-like root called hydrorhiza which is attached to a weed or any substratum. From hydrorhiza arises a vertical branching stem about 2.5 cm long which is known as a hydrocaulus. The hydrorhiza and hydrocaulus are hollow tubes.