Difference Between Polyp And Medusa Body Forms Of Coelenterates

What Is Polyp?

Polyp is 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 upper, or free, end of the body, which is hollow and cylindrical, typically has a mouth surrounded by extensible tentacles that bear complex stinging structures called nematocysts. The tentacles capture prey, which is then drawn into the mouth. The lower end of the polyp typically is adapted for attachment to a surface. The body wall consists of an ectodermal, or outer, layer and an endodermal, or inner, layer.

Members of one class of cnidarians, the Anthozoa, exhibit only the polyp body form; most species of the other three classes (hydrozoans, scyphozoans, and cubozoans) alternate in their life cycles between polypoid and medusoid (free-swimming) body forms. In general, the jellyfish-shaped medusae are produced asexually by the polyp, whereas sperm and eggs are produced by the medusae.

What You Need To Know About Polyp

• Polyps are anchored; rigid barely moving species found near the tidemark, they are attached to rocks.
• Polyp has a tubular body with a protracted stalk.
• Polyps do not possess any sense organs.
• Polyp is a sessile organism.
• Polyp can reproduce asexually by budding or sexually by spawning following the release of pheromones.
• Manubrium is directly upward since the body is attached to a surface.
•  The gastrovascular cavity of polyp is simple and lacks radial and circular canals.
• Polyps are a relatively primitive form of cnidarians.
• Polyps can give rise to more polyps as well as medusa through budding.
• Polyps lack gonad.
• A fine parchement referred to as vellum is absent in a polyp.
• Polyp is found attached to rocks near water mark.

What Is Medusa?

 Medusa is one of two principal body types occurring in members of the invertebrate animal phylum Cnidaria. It is the typical form of the jellyfish. The medusoid body is bell- or umbrella-shaped. Hanging downward from the centre is a stalklike structure, the manubrium, bearing the mouth at its tip. The mouth opens into the main body cavity, or enteron, which connects with radial canals extending to the outer rim of the bell. The medusa is a free-swimming form; it moves by rhythmic muscular contractions of the bell, providing a slow propulsive action against the water. The other principal body type of the adult cnidarian is the polyp, a stalked, sessile (attached) form.

What You Need To Know About Medusa

• Medusa are freebie floating, found in open water.
• Medusa has saucer or bell shaped body with shortened trunk for example jelly fish.
• Medusa possesses photoreceptors and gravity-sensing statocytes surrounding the bell.
• Medusa is a free swimming organism.
• Medusa reproduces exclusively sexually by gametes.
• Manubrium hangs down since the base is above.
• The gastrovascular cavity is the stomach and it consists of four radial canals and one circular canal.
• Medusa are much more evolved and complex form of cnidarians.
• Medusae can only give rise to medusae.
• Medusa has four gonads on radial canals.
•  A fine parchement referred to as vellum is present in Medusa.
• It is found in open waters.

Also Read: Difference between protonephridia and metanephridia

Difference Between Polyp And Medusa In Tabular Form