endrik Hoving and Bruce Robison from the Monterey Bay Aquarium Research Institute (MBARI) analysed footage of 170 vampire squids, taken over the last decade by the institute’s submersibles.
The videos, along with feeding experiments on captive vampire squids, revealed that they use their filaments like mobile spider webs. They extend these into the surrounding water to ensnare particles of food falling from above. The filaments are covered in tiny hairs, probably for catching these particles. They also have neurons that connect to a particularly large part of the creature’s brain, presumably so it can sense what’s stuck to its fishing lines.
When the time is right, it retracts the filaments, transfers the food to its other arms, and coats them in mucus secreted from its arm tips. It then conveys these delicious balls of mucus-bound detritus into its mouth, possibly with the help of the spines within its cloak.
This strategy is very different to that of other cephalopods, most of which are active hunters that attack and kill their food. Vampire squids are definitely not that, as Hoving and Robison confirmed by checking the stomachs of captured specimens. They found eggs, algae, pellets of faeces, bits of jelly, crustacean body parts—antennae, eyes, some shells, whole copeopods—and flesh from another deep-sea squid. In both kind and quantity, these remnants don’t reflect the diet of a hunter.
Instead, Hoving and Robison think that the vampire squid is mainly a ‘detritivore’ – a rubbish-eater. With few predators in the oxygen minimum zone, it can afford to sacrifice powerful swimming muscles or a high metabolism. Instead, it leads a relatively passive lifestyle, collecting the plentiful snowing debris with its two modified arms. With these adaptations, it can greatly extend the reach of its mouth, while its body—and its life—literally hangs in the balance.
Reference: Hoving & Robsion. 2012. Vampire squid: detritivores in the oxygen minimum zone. Proc Roy Soc B http://dx.doi.org/10.1098/rspb.2012.1357
All images from Hoving and Robison
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