An adult swimming cnidarian is called a medusa.
The free-swimming adult form of a jellyfish is called a medusa. This stage is characterized by its bell-shaped body and tentacles that hang down, allowing it to swim by pulsating its bell. Medusae are typically the reproductive stage in the jellyfish life cycle, producing gametes for sexual reproduction.
MedusaMedusa
POLYP
Jellyfish spend most of their life as a medusa, the umbrella-shaped adult form, while in their life cycle. Medusae are the free-swimming, bell-shaped form of jellyfish that you typically see in the ocean.
Medusa body form. Medusa-Umbrella shaped, tentacles hanging down. Swim about.
Jellyfish reproduction involves several different stages. In the adult, or medusa, stage of a jellyfish, they can reproduce sexually by releasing sperm and eggs into the water, forming a planula. In this larval stage of jellyfish life, the planula hooks on to the bottom of a smooth rock or other structure and grows into another stage of jellyfish life, the polyp--which resembles a miniature sea anemone. During this stage, which can last for several months or years, asexual reproduction occurs. The polyps clone themselves and bud, or strobilate, into another stage of jellyfish life, called ephyra. It is this form that grows into the adult medusa jellyfish.
Collective nouns for jellyfish are:a bloom of jellyfish (When jellyfish are spawned from their polyps they form what is called a "bloom".)a brood of jellyfisha fluther of jellyfisha smack of jellyfisha smuck of jellyfisha smuth of jellyfisha stuck of jellyfisha swarm of jellyfishA fluther or a smuth of jellyfish.A group of jellyfish is called a smack of jellyfish.
Jellyfish go through two life history stages throughout their lifetime, the first form is called a polypoid and the second is the jellyfish.
It starts as a sessile polyp like creature and then buds to form motile medusoid adults.
Jellyfish exist as either a medusa (adult free-floating) or polyp (immature attached) form during their life cycle. Another example is the Portuguese Man o' War, which also has a medusa (floating) and polyp (attached) stage.
Strobilation
it is called adolescence