January 24, 2014 | 1
The Monterey Bay Aquarium Research Institute have released more of the kind of footage they’re great at collecting – never before seen by humans. This time it’s of a black-eyed squid (Gonatus onyx) and an owlfish (Pseudobathylagus miller) locked in mortal combat in the deep sea.
The narrator does a great job at explaining what’s going on here, blow by gross blow, but here are the highlights:
* Black-eyed squid snares owlfish with its two tentacles, which are tipped with hooks and suckers, and reels it in.
* Black-eyed squid gnaws away at the owlfish’s spinal cord using its very sharp beak.
* Owlfish is wearing a suit of large, shaggy scales, which it proceeds to shed in an effort to loosen the black-eyed squid’s eight-armed grip.
* Owlfish’s scale trick doesn’t work, squid burrows deeper into its back muscles, rotating it around it a cob of corn
* Owlfish dies with a gaping, red, meaty hole in its back and the drinks are on black-eyed squid because he’s feeling pretty great right now.
So : ( but : ) depending on whose side you’re on.
Black-eyed squids might look like heartless killing machines, but they’ve got plenty of complex stuff going on, which we know about thanks to a couple of behavioural studies carried out by Associate Professor of Biological Sciences at the University of Rhode Island, Brad Seibel, and his colleagues just over a decade ago. The species is found as deep as 1500 m below the surface of the North Pacific Ocean, and they’re pretty common along their range from the coast of Japan to California. They’re fairly small, with a mantle length of about 18 cm, and they have two long, muscular tentacles from which they wield a single hook, which gives them their other name – the clawed armhook squid.
Things can be pretty tough in the deep sea for a young squid. They’re transparent as juveniles, which is a bonus, but they also inhabit shallower depths than their parents, which means more predators. So young black-eyed squids will often travel in schools. This is such a good strategy that sometimes octopuses will join in to form a delicious-sounding ‘mixed cephalopod shoal’.
The juveniles are also (understandably) pretty skittish – quick to flee and quick to ink. Even before Seibel and his team’s remotely operated vehicle (ROV) caught a glimpse of these babies, they’d likely already be jetting off, expelling ink everywhere in a clever squid shape known as a pseudomorph. If the young squids didn’t feel like fleeing just yet, they would hang in the common ‘J’ squid posture, which involves curling the arms and tentacles up over the head. Adults assume this posture too when they’re eating, so it could just be an easy resting stance.
When they do decide to make a break for it, the young squids would change their chromatophore (cells that control colouring) patterns to produce a dark stripe down the middle of the mantle, and also ‘eyebrow patches’, which cover the large reflective lobes of their brains.
After about three months, the young squids will grow into adulthood and develop an orange or white colouring and some real attitude.
Adult black-eyed squids live alone in the safety of deeper waters, so there’s no longer any need to form protective schools. When faced with an ROV, Seibel and colleagues noted that they stood their ground, and were much more reluctant to jet away like their younger selves.
But if they thought things were going to get ugly, the adults would react with a series of defensive postures including the ‘elk’, which involves turning towards the submersible with arms and tentacles spread wide (very intimidating for a robot) and the ‘praying’ posture, which involves swimming slowly away with the tentacles locked together via the single hooks. So exactly what it would look like if you imagined a squid praying.
What also came out of this research is evidence that black-eyed squids make pretty great mums. In 2000, Seibel and his colleagues managed to catch two older females, fragments of an egg mass, plus a bunch of live hatchlings from depths between 1250 and 1750 m off the coast of California. The females both had no tentacles, so the team suggested that this allowed them to carry egg sacs in their arms. These sacs could contain between 2000 and 3000 eggs, and would develop over a period of nine months. Later in 2006, a MBARI remotely operated vehicle called Tiburon captured an incredible image (above) confirming just that.
Seibel and his team also found tiny hooks on the females’ arms, which appear to help them grasp onto the sac, and they found that as they moved through the ocean, sometimes at depths of up to 2,500 m, the females would gently pump water through the egg sac. This causes the sac to inflate, which gives the eggs access to a constant supply of fresh water and oxygen.
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