Cnidarians are important group in animal kingdom. Cnidaria moreover known as vicious specie consists of hydra, jellyfish, coral and sea anemones. They are mushy and squishy in nature nevertheless all have performance to sting their prey or for defense. They are carnivorous. Coral and sea pens produce calcium carbonate to type themselves as a rock for his or her security. There are two physique sorts of aquatic invertebrate phylum cnidaria known as polyp and medusa. The foremost between them is, the polyps are cylindrical and typically fixed kind of cnidarians whereas medusas are free motile kind of cnidaria and typically an umbrella like.
Polyps are barrel- shaped and immobile specie of Cnidaria. They majorly include hydra, coral and sea pen as cnidarians specie. It represents the asexual part of hydra and scyphozoa. Coral and sea anemone are pure polyps. Polyps join itself to flooring and on the other prime facet are its mouth and tentacles. It has an elongated axis. Polyps can each be solitary or in groups. the groups could also be hook up with flooring or each other. The keep fast known as paddle disc holds the polyp in a position. Mesoglea is preset between the one layered ectoderm and endoderm nevertheless it is not that so much thick. It is taken under consideration to be dwelling fossils as even after the mass extinction event it is nonetheless surviving since better than half a billion years. They are relying on others and reproduce by means of asexual budding.
The umbrella like motile medusa is free to maneuver. It represents the sexual part. It is retrograde kind of polyp. Medusa is flattened sac-like floating with its mouth going via down and tentacles above. The larger physique of medusa is known as exumbrella whereas the lower half is known as subumbrella. In Portuguese man-of-war the upper half known as exumbrella are barely convex and usually spherical or egg-shaped whereas subumbrella is concave. There are three kind of tentacles. Every set of tentacle play completely totally different place, like one set is accountable for duplicate, the other is accountable for security whereas one set is for feeding. The occasion of medusa is jelly fish. Between the one layered ectoderm and endoderm is a jelly like substance known as Mesoglea which makes the physique wall thick. Medusa also have a air cavity known as pneumatophore, that’s accountable to take care of the specie floating inside the water column. Medusa may even be solitary or in colonies. If in colony it has related pneumatophore as totally different.
- Polyps are anchored, rigid barely shifting specie found near the tidemark, they’re related to rocks whereas medusas are freebie floating, current in open water.
- Polyp has a tubular physique with a protracted stalk whereas medusa has saucer shaped physique with shortened trunk as an illustration jelly fish.
- In polyp the physique is related beneath thus the manubrium is skyward whereas in medusa base is above so that manubrium hover earthwards.
- A top quality parchment known as vellum is absent in a polyp whereas it is present in a medusa.
- There is not any sense organ to essentially really feel the setting spherical in a polyp whereas on the bottom is eight adradial tentacles that give sensation to medusa.
- An simple gastro vascular cavity is found inside the polyp with none radial or spherical canals whereas in medusa gastro vascular represents stomach, four radial canals and one spherical canal is preset.
- There is not any gonad in a polyp whereas in medusa on radial canals, there are four gonads.
- Polyp reproduces abiogenetically whereas medusa replicates sexually.