Meet the residents of Australia's octopus cities
In this week's edition of Metro Science, our Citizen Scientist Genna Buck takes us on a tour of Octlantis, an underwater urban enclave filled with octo...puses? Ocotopi?
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Some of the smartest creatures under the sea, the Australian Octopus tetricus, or gloomy octopus, typically live solitary lives. Until now. Researchers, spying with cameras and divers, found a group of 15 octopuses living together and exhibiting complex behaviours in what can only be called a city. Octopus cities aren’t exactly like human cities, so there’s no real division of labour. Octopuses do different jobs at different times.
Meet the residents of this underwater utopia:
Octo chef: Octopus cities aren't exactly like human cities, so there's no real division of labour. Octopuses do different jobs at different times. First up: finding food. Luckily, Octlantis is surrounded by beds of scallops.
Octo engineer: After chowing down, octopuses pile discarded shells into a foundation, sculpting dens (octo-equivalent to studio apartments). The shell bed solidifies over time, attracting other species to the city. This makes octopuses true "ecosystem engineers," scientists say.
Octo landlord: A diver's camera caught a cranky landlord octopus reaching its tentacle into a neighbour's den, hauling him out and chasing him away. The evicted tenant swam for his life to a den at the other end of Octlantis, only to be pursued by the landlord and evicted again.
Octo sheriff: A dozen octopuses in a small area is remarkable, but Octlantis isn't big enough for just anyone. Octopuses show their peers who is not welcome 'round these parts by charging at newcomers, standing tall, spreading their tentacles wide and turning a dark colour.
Octo lovers: Normally the gloomy octopus only hangs out with others of its species when it's time to mate. But in Octlantis, they bunk close enough to be in tentacles' reach of one another, and scientists found they often chose to mate with their next-door neighbours.
Building blocks of octopus cities:
No. 1: A hard surface to build on. No. 2: Lots of food around, so octopuses can stay put. The same factors are present a few hundred metres away in Octopolis, the only other cephalopod city ever found. Thought to be a freak occurrence possible only because the octopuses built it on top of a human-made chunk of metal on the sea floor, the discovery of Octlantis disproved this.
City living has costs: Building expends energy and chasing another octopus out of town exposes you both to predators. What benefits do these eight-legged urbanists get in exchange? That’s a topic for future study.
Most scientists use the straightforward plural octopuses. Octopi is based on an old misunderstanding of how to pluralize Latin words (but octopus is an English word, created from a Greek root). If you want to be fancy when talking about more than once octopus, you can use octopodes.
A cephalopod is a member of the class of undersea animals that includes octopuses, squid, camouflaging cuttlefish, and the freaky-looking nautilus, ancient squid-like creatures with shells. Cephalopods are part of the group of marine invertebrates called mollusks, which also include snails and slugs, clams and oysters.
SOUND SMART: Your science vocab for the week
A cephalopod is a member of the class of undersea invertebrates that includes octopuses, squid, cuttlefish, and nautilius, ancient squid-like creatures with shells.
USE IT IN A SENTENCE: That bartender is serving so many people their drinks at once, he must be a cephalopod.
SCIENCE STORY: It's hard to be hard of hearing
A UK review of 70 previous studies found that, if you have a loved one with hearing loss, it's normal to want to ring their neck sometimes. The condition, which is extremely common and usually incurable, is especially draining on spouses, friends and family members, the research found. Taking on total responsibility for the telephone, arguing over the volume of the radio or TV, having to repeat yourself often and struggling to involve the hard-of-hearing person in conversation are just a few of the stressors. The researchers also found that family members may be a better judge of their loved one's level of hearing loss. The patient themselves may be in deep denial about their growing disability, or have compensated so much that they've closed their ears to how bad things have gotten.