The division Cnidaria contains species that only occur in the polyp phase aka anthozoans, species that only occur in the medusa stage Cnidarians, and species that occur across both life cycle phases are Cnidaria Hydrozoans.
Well, this article only concentrates on pointing out the distinct features and differences between the two phases i.e. polyp phase and medusa phase of the Cnidaria phylum.
Polyp vs Medusa
The difference between polyp and medusa is that the ability to locomote, polyps are stagnant animals with no ability to freely swim whereas medusae class organisms can freely swim in the seawater. Now, both the forms are Cnidarian aspects, and thus the basic life processes are similar however, the polyps usually have a long stalk attached to the center of their body like the Hydra is a good example whereas the coelom or cavity is found in the medusae members like the flat or box jellyfishes.
In biology, a polyp is one of 2 key body shapes seen in inhabitants of the Cnidarian animal kingdom. The polyp is solitary and sessile and can be isolated, as in a sea anemone, or a coral.
Medusa, on the other hand, is the second body form obtained by the Cnidarians. Looking carefully, it is significantly a good example to consider box jellyfish’s common form. The umbrella-like and drooping structure of a medusoid is its key appearance indicator.
|Parameters of Comparison||Polyp||Medusa|
|Locomotion||Polyps are sessile animals which cannot swim and usually stay attached to the same place forever.||Members of medusae can swim freely in open water.|
|Sensory Organs||No sensory organs are present and nervosa ring is absent as well.||Statocysts are present and the sensory part is adradial tentacles which are usually 8 in number.|
|Reproduction Phase||Reproduces asexually (budding) or sexually and gives birth to either a polyp or a medusa.||Reproduces to give birth to a medusa only. Mode is sexual and using gametes.|
|Body Shape||Cylindrical and tubular structure||Saucer-like and usually looks like an umbrella.|
|Examples||Sea anemones, sea fans, coral and sea pens.||Jellyfishes, mawsonites, rhizostomeae etc.|
What is Polyp?
A polyp is made up of a tube with an opening encircled by tendrils, referred to as a “head,” and a foot-like disc connected to the base. The opening and tendrils are pointing in the direction of the ocean water flow to trap the planktons for food.
Some species of corals are hermaphrodites and the gender depends upon the temperature of the water they reside in. Budding happens when a spherical area of tissue is evaginated during asexual reproduction.
The opening or the upper mouth of the creature is at the opposite end of the cylinder, encircled by tentacles that create the “head.” The mouth and tendrils are pointing towards the water.
Individuals in a swarm of invertebrate sea organisms belonging to the group Bryozoa are occasionally referred to as polyps, although they are typically referred to as zooids the name for these phyla (polyp) is derived from zooids themselves.
What is Medusa?
Medusa is a Cnidaria phylum organism’s movable life cycle phase. Hydrozoa taxa can take the form of medusas or jellies. A medusa is anatomically created by a bell susceptible to muscular activity, allowing it to move and swim.
The top or aboral exterior has named the exumbrella (which looks like the exterior of an umbrella), and the bottom part is called the subumbrella.
The gastrovascular chamber and projecting tubes that stretch forward towards the edge make up the gastrointestinal cavity; these channels can be basic or branched, and their quantity can range from a few to a lot.
Scyphozoa (the popular, multicolored, big jellies like the box jellyfish) and Cubozoa are the most frequent medusa species. Because those are the only groups in which medusae may be found, except for aquatic hydrozoans.
Main Differences Between Polyp and Medusa
- Polyps have a simpler gastrointestinal system whereas medusae have a complex digestive system.
- Polyps can reproduce sexually as well as asexually whereas medusae can only reproduce sexually by gametes.
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