The Insane Biology of: The Octopus

Fossil records show cephalopods evolved over 500 million years ago long before any fish reptiles or mammals appeared on Earth as early ancestor quite small with shell protecting itself crawling along ocean bottom being members of mollusk phylum.

Around 140 million years ago lineage that produced octopus lost shells making them nimble agile creatures but also rather vulnerable where survival of soft-bodied creatures for millions of years seems unlikely in sea full of dangerous hungry predators yet this vulnerability may be precisely what allowed octopus to become remarkable.

Because octopus has almost no hard parts at all except beak it can squeeze through any hole as long as larger than eyeball allowing octopus to hide in very small crevices providing evolutionary advantage when escaping large predators like sharks or dolphins.

Chromatophores organs speckled across octopus skin like freckles contain tiny pigment-filled sacks like balloons full of different colored dye either black red or yellow surrounded by radial muscles stretching sac to reveal pigment color producing patterns such as bands stripes or spots.

For colors outside black red yellow octopus uses another layer of reflective structures called iridophores as stacks of thin cells beneath chromatophores containing reflectin protein bouncing certain wavelengths back out creating metallic blues greens while leucophores beneath reflect ambient light producing white hues.

Using structure called papillae octopus can change texture of skin creating ridges and bumps that rise and fall helping octopus match surroundings even better where with all these tools shell-free soft-bodied octopus able to deceive ocean full of predators for millions of years.

When octopus travels along sea floor must assess background and modify camouflage constantly making decisions at rapid pace where one researcher observed octopus changing camouflage 177 times in one hour with reaction times up to 200 milliseconds fast as fastest blink you can do.

Despite doing so much with color octopus and almost all cephalopods surprisingly thought to be colorblind creating mystery of how they can match colors they cannot even see requiring explanation for this apparent paradox in sensory capabilities.

In 2015 answer to colorblind paradox started being uncovered as researchers found octopus skin sensitive to light due to photoreceptor genes active in skin where even detached skin could respond to light and change chromatophore shape revealing octopus can see with not just eyes but also skin.

Octopus can change colors so fast because octopus controls chromatophores neurally whereas other color-changing animals like chameleons take much longer because their color change hormonally controlled where hormones take time to reach blood and distribute around body with color change taking over 20 seconds when controlled this way.

Common octopus has around half billion neurons in body where for comparison humans have about 100 billion while most invertebrates have much less like snails with only 20,000 neurons but cephalopods score in same range as vertebrates like cats dogs parrots with only third of 500 million in brain and majority in eight arms.

Severed octopus arm can respond to stimuli hour after being separated from central brain where recent paper revealed extent of autonomy using video modeling showing in flow of information from environment to octopus some information bypasses central brain entirely with suckers and arms thinking for themselves allowing extremely quick analysis and reaction.

To find where humans split from octopus must travel to around 600 million years ago where creature found is simple flatworm with extremely basic nervous system and no inklings of what we would consider intelligence representing divergence point before intelligence evolved separately in both lineages.

In humans intelligence commonly defined as ability to think abstractly understand communicate problem solve learn form memories and plan actions usually measured by intelligence tests given numerical value but cannot give standardized test to octopus only observe their behaviors to assess cognition.

Famous example called coconut carrying octopus where octopus going to place with no shelter takes coconut halves and when wants to stop and rest picks them up and brings them together as composite tool use behavior previously thought only in humans some primates some birds indicating complex intelligence for two reasons.

Octopuses do well in memory tests and can differentiate between different people even when wearing same outfit demonstrating sophisticated memory and recognition capabilities beyond simple visual pattern matching requiring cognitive processing to distinguish individuals despite identical clothing.

Professor Mather studied common octopus playfulness where octopuses in aquarium with hiding place and nothing else given pill bottle floating at surface where water intake pump created current pushing bottle across tank and octopus shot water jet at it making it return with some octopuses doing this 14 to 21 times being marine equivalent of bouncing ball.

Social intelligence hypothesis often favored for evolution of complex cognition suggesting intelligence evolved due to demands of group living such as maintaining complex enduring social bonds deception cooperation or social learning but this theory cannot explain why intelligence evolved in cephalopods requiring different explanation for non-social creatures.

Perhaps pressures of finding food and evading predation is enough for intelligence to blossom forming basis for ecological intelligence hypothesis suggesting complex cognition evolved to meet challenges associated with predation foraging and competitive pressures where when octopus lost shell 140 million years ago perhaps predation pressure so high that outsmarting attackers became only survival way.

Around 500 million years ago during period called Ordovician known for amazing diversity of invertebrates the massive armored cephalopods were king dominating seas for roughly 360 million years where fossil records show amazing array of creatures some we recognize and some we definitely do not until life nearly stopped in first mass extinction.