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The Blue-Ringed Octopus — Reading Comprehension

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MS-LS2-1
RI.6.3
RI.7.3
RI.8.8

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This NGSS aligned passage explores how the tiny blue-ringed octopus impacts its ecosystem through predator-prey relationships. Students learn about its venomous hunting of crabs/shrimp, role as prey for moray eels, and how its territorial behavior creates 'halo effects' that protect surrounding coral. The text covers symbiotic bacteria producing tetrodotoxin, warning displays, and conservation status.

CONTENT PREVIEW

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The blue-ringed octopus (Hapalochlaena species) is a master of survival in its coastal ecosystem. Though small enough to fit in your palm, this creature plays several critical roles in maintaining balance in its environment.

Found throughout the tidal pools and coral reefs of the Pacific and Indian Oceans, these octopuses thrive in shallow waters from Australia to Japan. As both predator and prey, they occupy a vital position in the food web, controlling populations of small crustaceans while providing food for larger reef species.

Their hunting activities help regulate the numbers of crabs and shrimp, preventing these species from overgrazing on important reef organisms. By creating small dens in rocky crevices, they modify their microenvironment, providing shelter for other small creatures when abandoned.

Deadly Adaptations

This small octopus contains some of the ocean's most remarkable survival tools:

● Warning Display: When threatened, vibrant blue rings flash across its skin as one of nature's clearest "don't touch" signals.

● Potent Venom: Carries enough tetrodotoxin to paralyze 26 adult humans - making it one of the most venomous marine animals.

● Surgical Strike System: The venom, produced by symbiotic bacteria, is only injected when hunting prey through its beak.

● Stealth Mode: Can change color and texture to disappear into surroundings when not actively warning predators.

Fun Fact: A single blue-ringed octopus can influence an area 10 times its size by creating a "halo effect" - prey species avoid its territory, which indirectly protects nearby coral and algae from overgrazing!

Where are blue-ringed octopuses primarily found?

Deep ocean trenchesShallow tidal pools and reefsFreshwater lakesArctic waters

Which organism is NOT part of the octopus's food web?

CrabsShrimpMoray eelsSeaweed

Why is this small octopus important to its ecosystem?

It builds coral reefsIt regulates prey populationsIt cleans the ocean floorIt produces oxygen

What is the main function of their blue rings?

PhotosynthesisWarning predatorsAttracting matesTemperature regulation

How does the octopus obtain its venom?

From special glandsFrom symbiotic bacteriaBy eating poisonous plantsThrough ocean water

The word "tetrodotoxin" refers to:

The octopus's camouflage abilityIts deadly neurotoxinIts reproductive processIts swimming style