Obelia, genus of invertebrate marine animals of the class Hydrozoa (phylum Cnidaria). The animal begins life as a polyp—a tentacled, stalklike form resembling a small sea anemone attached to the ocean bottom or some other solid surface. The polyp asexually produces medusae, or jellyfish.

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Considering this, what is a polyp stage?

Polyp is a sessile life cycle stage of the species belonging to the Cnidaria phylum. Adult corals and sea anemones are examples of polyps. A polyp is formed by a tube with a mouth surrounded with tentacles, referred to as a “head”, and is attached to the bottom with a foot-like disk.

Additionally, what is the function of a polyp? Polyps extend their tentacles, particularly at night, containing coiled stinging nettle-like cells or nematocysts which pierce and poison and firmly hold living prey paralysing or killing them. Polyp prey includes copepods and fish larvae.

Secondly, is obelia a polyp or medusa?

Obelia is a genus of hydrozoans, a class of mainly marine and some freshwater animal species that have both polyp and medusa stages in their life cycle. Hydrozoa belongs to the phylum Cnidaria, which are aquatic (mainly marine) organisms that are relatively simple in structure. Obelia is also called sea fur.

What is the difference between a polyp and a medusa?

Most of the Cnidarian classes utilise polyp and medusa as two stages of their life cycle. Polyps are sessile and asexually reproduce by budding. But, medusa reproduces sexually by producing sperms and eggs. The key difference between polyp and medusa is that polyp is sessile whereas medusa is free-swimming.

Related Question Answers

What is an example of a polyp?

The polyp is a sessile, or nonmotile, organism; well-known solitary polyps are the sea anemone and the freshwater hydra. The medusa, when free swimming, is popularly known as a jellyfish.

What are called polyps?

Coral polyps are tiny, soft-bodied organisms related to sea anemones and jellyfish. At their base is a hard, protective limestone skeleton called a calicle, which forms the structure of coral reefs. Reefs begin when a polyp attaches itself to a rock on the sea floor, then divides, or buds, into thousands of clones.

What are cancerous polyps?

Colorectal cancer usually begins as a "polyp," a nonspecific term to describe a growth on the inner surface of the colon. Polyps are often non-cancerous growths, but some can develop into cancer. The two most common types of polyps found in the colon and rectum include: Hyperplastic and inflammatory polyps.

How do polyps reproduce?

Corals can reproduce asexually and sexually Through budding, new polyps “bud” off from parent polyps to form new colonies. Once attached, they metamorphose into a coral polyp and begin to grow, dividing in half. As more and more polyps are added, a coral colony develops and eventually begins to reproduce.

Is sea anemone a polyp or medusa give reasons?

As cnidarians, sea anemones are related to corals, jellyfish, tube-dwelling anemones, and Hydra. Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle. Sea anemones also breed asexually, by breaking in half or into smaller pieces which regenerate into polyps.

What do polyps do?

A polyp is a growth of tissue on the lining of the colon and rectum that projects into the intestines. People with colon polyps usually have no symptoms. Most colon polyps are harmless, though some types can become cancerous. Polyp removal is the best way to treat colon polyps and prevent cancer from developing.

Do polyps reproduce sexually?

Corals can reproduce asexually and sexually. In asexual reproduction, new clonal polyps bud off from parent polyps to expand or begin new colonies (Sumich, 1996). This occurs when the parent polyp reaches a certain size and divides.

Which animal is a Medusa?

jellyfish

What is the polyp stage of a jellyfish?

Jellyfish have a stalked (polyp) phase, when they are attached to coastal reefs, and a jellyfish (medusa) phase, when they float among the plankton. The medusa is the reproductive stage; their eggs are fertilised internally and develop into free-swimming planula larvae.

What is a polyp cnidarian?

Polyp, in zoology, one of two principal body forms occurring in members of the animal phylum Cnidaria. The polyp may be solitary, as in the sea anemone, or colonial, as in coral, and is sessile (attached to a surface). The lower end of the polyp typically is adapted for attachment to a surface.

What is obelia Medusa?

Common name(s): Sea plume, branched Obelia Description: The Obelia dichotoma medusa is a small hydromedusa with the bell diameter greater than its height. It has no ocelli. The manubrium is short. More than 16 unbranched tentacles, all about the same size, are distributed evenly along the margin of the bell.

Do all three classes of cnidarians have both Medusa and polyp stages?

They have two different morphologies: a polyp stage and a medusa stage (not all classes will have both through out their life time). Both stages have radial symmetry. The polyp stage tends to be sessile and the medusa stage is mobile. Some species of Cnidarians have bioluminescence.

Does Hydra have medusa stage?

Most species of hydra are less than 15 mm long (not including the tentacles). Life cycle: Cnidarians alternate between the polyp and medusa life forms. In hydra, the medusa stage is absent and polyps reproduce both sexually and asexually.

What is a Hydranth?

Definition of hydranth. : one of the feeding zooids of a hydroid colony.

How do polyps and medusae reproduce?

polyp and medusa: Reproduction. The medusae then produce new polyps by sexual reproduction. A medusa produces eggs or sperm, which are usually shed into the water; when an egg is fertilized, it develops into a swimming larva, which eventually settles and grows into a polyp.

What structures determine whether a polyp of obelia is a Gastrozooid feeding polyp or a Gonozooid?

The first is the gastrozooid, which is adapted for capturing prey and feeding. In Obelia, all polyps are connected through a common digestive cavity called a coenosarc. The other type of polyp is the gonozooid, adapted for the asexual budding and the production of sexual medusae.

What is Metagenesis in biology?

Alternation of generations, also called metagenesis or heterogenesis, in biology, the alternation of a sexual phase and an asexual phase in the life cycle of an organism. The two phases, or generations, are often morphologically, and sometimes chromosomally, distinct.

What is polyp in biology?

Definition. noun, plural: polyps. (1) (zoology) The hollow, columnar, sessile form of Cnidarians (as opposed to the medusa form) (2) (pathology) An abnormal (usually benign) pedunculated growth, protruding from a mucous membrane.

What is a polyp Hydra?

Hydra are small polyps from 1 to 20 mm in body length. The body is crowned by up to 10 or 12 tentacles. Usually the tentacles are approximately the same length as the body but may be somewhat shorter, particularly in the green hydra, and can exceed 20 cm in length in hungry brown hydra in quiet water.