What is a Medusa jellyfish?

You're likely thinking of the Medusa form of a jellyfish, not a specific species called "Medusa jellyfish". Here's why:

* Medusa is a stage in the life cycle of most jellyfish. It's the familiar bell-shaped form with tentacles we often think of.

* Jellyfish is a general term for various species of marine animals belonging to the class Scyphozoa.

So, when you hear "Medusa jellyfish", it's usually a way of emphasizing that the jellyfish is in its most recognizable form.

Here's how the life cycle of a jellyfish works:

1. Planula larva: A fertilized egg develops into a free-swimming larva.

2. Polyp: The larva attaches itself to a surface and grows into a polyp, a stalk-like structure.

3. Strobila: The polyp begins to reproduce asexually, forming a stack of discs called a strobila.

4. Ephyra: The discs detach from the strobila and develop into small, immature jellyfish called ephyra.

5. Medusa: The ephyra matures into the adult jellyfish form, the medusa.

So, while there isn't a specific "Medusa jellyfish" species, the term is used to refer to the familiar free-swimming stage of a jellyfish's life.

Let me know if you'd like to learn more about specific jellyfish species or their life cycle!