Semaeostomeae
The Semaeostomeae is a suborder of jellyfish within the order Rhizostomeae. These jellyfish are commonly known as “true jellyfish” or “disk jellyfish.” They are characterized by their distinct, flat, disk-shaped bell and their possession of tentacles with stinging nematocysts. These stinging cells are used for defense and capturing prey, typically small crustaceans and fish.
Common Names
The Semaeostomeae are commonly called "true jellyfish" or "disk jellyfish."
Characteristics
The Semaeostomeae are characterized by their flattened, disk-shaped bell, which can range in size from a few centimeters to several meters in diameter. They possess tentacles that hang from the bell's edge, and these tentacles are equipped with stinging nematocysts for defense and predation. The mouth is located on the underside of the bell, and it opens into a gastrovascular cavity that is used for digestion and circulation.
They are typically free-swimming and move by contracting their bell muscles.
Environments
Semaeostomeae jellyfish are found in all the world's oceans, in both coastal and open-ocean waters. They can occur in a range of temperatures and salinities, but they are most abundant in warm, tropical waters. They are generally found in the pelagic zone, which refers to the open ocean.
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