Cnidaria · cnidarians

Upside-down jellyfish

Cassiopea xamachana

Cassiopeidae · upside-down jelliesIUCN: Not evaluated
Upside-down jellyfish
Photo: Marco Almbauer · Public domain · Wikimedia Commons · resized

A jelly that lies bell-down in shallow lagoons and mangroves with its tentacles facing the sun.

Fun factIt releases stinging mucus 'grenades' into the water, so swimmers can be stung without touching it.

Waters
Tropical Atlantic & Caribbean
Depth zone
Coastal shallows & estuaries
Diet
Symbiotic algae & plankton
Size
Bell up to 25 cm

Classification

Cnidaria › Scyphozoa › Rhizostomeae › Cassiopeidae

  1. Kingdom Animalia animals
    • Many-celled organisms that eat other living things for energy (heterotrophs)
    • Cells have no cell walls
    • Most can move at some stage of life
  2. Phylum Cnidaria cnidarians
    • Radially symmetric bodies with one opening that is both mouth and anus
    • Stinging cells (cnidocytes) fire tiny harpoons (nematocysts)
    • Two body forms: an attached polyp and a swimming bell (medusa)
  3. Class Scyphozoa true jellyfish
    • True jellyfish: the swimming bell (medusa) is the main life stage
    • Small polyps bud off baby jellies by splitting in stacks (strobilation)
    • Bell edge has sense organs (rhopalia) in notches
  4. Order Rhizostomeae root-mouth jellyfish
    • No tentacles on the bell edge
    • Instead of one mouth, oral arms have many tiny mouth openings
    • Includes the edible jellyfish of Asia
  5. Family Cassiopeidae upside-down jellies
    • Upside-down jellies that rest bell-down on the seafloor
    • Host algae in their arms and face them toward the sun
  6. Genus Cassiopea
    • Species in the same genus are very close relatives and often look alike.
  7. Species Cassiopea xamachana Upside-down jellyfish

Closest relatives in the guide