Mollusca · mollusks

Greater blue-ringed octopus

Hapalochlaena lunulata

Octopodidae · common octopusesIUCN: Least Concern
Greater blue-ringed octopus
Photo: Jens Petersen · CC BY 2.5 · Wikimedia Commons · resized

A small octopus that flashes iridescent blue rings when threatened.

Fun factIts saliva contains tetrodotoxin, the same toxin as in pufferfish.

Waters
Indo-Pacific
Depth zone
Coral reefs, Coastal shallows & estuaries
Diet
Small crabs & shrimp
Size
About 10 cm

Classification

Mollusca › Cephalopoda › Octopoda › Octopodidae

  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. Clade Bilateria bilateral animals
    • Body has a left and right side that mirror each other (bilateral symmetry)
    • Head end with concentrated nerves; three tissue layers
    • Includes about 99% of all living animal species
  3. Clade Protostomia protostomes
    • In the embryo, the first opening usually becomes the mouth
    • Main nerve cord runs along the belly (ventral)
    • Includes mollusks, worms, and arthropods
  4. Clade Spiralia mollusks, worms & kin
    • Embryos usually divide in a spiral pattern (spiral cleavage)
    • Many have a swimming larva with a band of cilia (trochophore)
    • Includes mollusks and segmented worms
  5. Phylum Mollusca mollusks
    • Soft body with a muscular foot and a fold of tissue (mantle) that makes the shell
    • Most have a rasping, tongue-like ribbon of teeth (radula)
    • Includes snails, clams, octopuses, and chitons
  6. Class Cephalopoda cephalopods
    • Foot is modified into arms and tentacles around the head
    • Large brains and camera-like eyes
    • Jet propulsion by squirting water through a funnel (siphon)
  7. Subclass Coleoidea octopuses, squids & cuttlefish
    • Shell is internal, reduced, or absent
    • Most have an ink sac and color-changing skin cells (chromatophores)
    • Includes octopuses, squids, and cuttlefish
  8. Superorder Octopodiformes octopuses & vampire squid
    • Eight arms, with no long feeding tentacles
    • Includes octopuses and the vampire squid
  9. Order Octopoda octopuses
    • Octopuses: eight arms with suckers and a rounded body with no internal shell
    • Can squeeze through any gap larger than their beak
  10. Suborder Incirrata finless octopuses
    • Finless octopuses with no fleshy filaments (cirri) on the arms
    • Most bottom-dwelling octopuses belong here
  11. Family Octopodidae common octopuses
    • Typical octopuses of reefs and coasts
    • Two rows of suckers on each arm in most species
  12. Genus Hapalochlaena
    • Species in the same genus are very close relatives and often look alike.
  13. Species Hapalochlaena lunulata Greater blue-ringed octopus

Closest relatives in the guide