Cassiopea

Common Names

Members of the genus Cassiopea are commonly called "upside-down jellyfish," "upside-down jelly," "flower hat jellyfish," or "upside-down medusa." These names reflect their characteristic resting position and sometimes the appearance of their oral arms.

Characteristics

Cassiopea jellyfish are distinguished by their distinctive appearance and behavior:

• Upside-down posture: They lie on the seafloor with their oral arms facing upwards, a behavior unique among jellyfish.
• Flattened bell: The bell is typically flat and saucer-shaped, with a diameter ranging from a few centimeters to over 30 cm.
• Oral arms: They have four prominent, branching oral arms that are covered in stinging nematocysts.
• Symbiotic algae: They host symbiotic algae, called zooxanthellae, within their tissues. These algae provide nutrients through photosynthesis, giving the jellyfish a distinctive greenish-brown color.
• Slow movement: Cassiopea jellyfish are relatively slow-moving and often pulsate rhythmically to circulate water over their oral arms.

Environments

Cassiopea species are primarily found in shallow, warm, and sheltered waters, such as estuaries, lagoons, and mangroves. They prefer areas with soft, sandy or muddy substrates where they can rest comfortably.

References

For more detailed information, you can visit these reliable websites:

• World Register of Marine Species (WoRMS)
• Animal Diversity Web
• National Geographic