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Blue-Ringed Octopus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Octopoda
Family:	Octopodidae
Genus:	Hapalochlaena Robson, 1929

The blue-ringed octopus, Hapalochlaena maculosa, native to the Pacific and Indian Oceans, is known as one of the ocean’s most venomous animals in the world. These pint-sized predators, ranging in lengths of eight to ten inches (twenty to twenty-five centimeters) are named for their chromatophore cells; organized in blue bright rings across their bodies and tentacles. Found in temperate soft, sandy bottoms of shallow tide pools and coral reefs, these miniature cephalopods use their blue rings as a defensive mechanism to warn potential predators. They produce a saliva containing symbiotic bacteria that serves as a potent nerve toxin that causes respiratory failure to anything it comes into contact with.

Physical Description

Despite there being four different species of blue-ringed octopus, all maintain a small size- between 20-25cm- and a yellow-brown coloration throughout their bodies with bright black and blue rings that pulsate when threatened.  Its appearance is subject to change though, as all blue-ringed octopuses are covered in chromatophore cells that allow each octopus to alter its coloration to its discretion.  They often use this to their advantage and camouflage among the coral reefs they reside in.

Distribution

The four subspecies of blue-ringed octopuses are distributed across the Pacific and the Indian Oceans, ranging from Japan to Australia. They can be found in Papua New Guinea, Solomon Islands, Philippines, and Indonesia and as far west as Sri Lanka.

Reproduction and Life History

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Before blue ring octopuses are ready to mate, they spend most of their lives in the sandy depths of the sea, where they live in empty sea shells and other crevices. The octopuses only leave their homes when they are ready to mate or to feed. The blue-ringed octopus is an oviparous organism, laying eggs to reproduce. During mating, the male octopus inserts it modified arm, or hectocotylus, into the oviduct of the female. This is after it attaches to the female. Then, the male octopus releases spermatophores inside of the female, fertilizing the eggs. The female lays her eggs in the benthic zone and incubates and protects them under her arms for as long as several months until they are ready to hatch. Once the fifty to 100 eggs hatch, the female will soon die. The female dies much later than the male as the male dies right after the eggs are fertilized. The new octopuses will be very tiny when born, yet it only takes them about thirty days to be able to capture prey and a year to become sexually active.

Feeding

The blue-ringed octopus is a carnivorous creature, that mainly feeds on small crustaceans, and occasionally small fishes during the day. To capture its prey, the blue-ringed octopus first ambushes it, pounces on the shell, and then uses its beak to pierce into the flesh, while secreting its venomous saliva. Once the saliva seeps into the flesh of the animal, the animal becomes paralyzed, allowing the octopus to tear its prey apart with its beak.

Ecology

This species of octopus can mainly be found in shallow reefs and tide pools. As mentioned before, they secrete venom when attacking their prey, however, there are two types of venom the animal can use. The first type of venom is used to paralyze prey, while the second type is used to protect the animal from its predators. The first type is not as toxic as the second, because the second is used for self-defense, and typically for larger animals. While there aren’t many animals who target this species, the few predators include sharks, snappers, moray eels, and groper fish. The predators have the element of surprise on their side, but the blue-ringed octopus can sometimes turn the predator into prey, if able to paralyze it with their saliva. Since these octopuses are so small, they are also able to find cover and protection in between rocks and shells. There is little known on the effects the blue-ringed octopus has on its habitat, however, they are likely helpful because of their contribution to controlling invasive crustacean populations.