Along with us humans, a range of hungry hunters prey on the scrumptious octopus.
The boneless octopus must avoid becoming lunch for sharks, eels, fish and even killer whales. But not all of the organisms that feed on octopuses are such charismatic megafauna.
Octopuses, both dead and alive, are part of the delicate, detailed food web hidden below the waves, which we are just beginning to discover.
One Antarctic expedition, analyzed in December, found a tiny species of sea snail—previously unknown to that part of the planet—feasting on the decomposing beak of a deceased octopus. This Bathysciadiid limpet was having a grand dinner at about 1,400 meters below the surface in Pine Island Bay (in the Amundsen Sea, along the west coast of the continent). The findings were described in Continental Shelf Research. Though more modest than a 200-ton whale fall, an octopus corpse—or even just part of it—can sustain many organisms, both macro and micro.
During its life, the octopus hosts a menagerie of parasites and hangers-on inside its body. As we are home to trillions of microbial cells, the octopus body makes a cozy habitat, serving up meals for many of its own specialized inhabitants.
The best-known octopus microorganisms actually live in the animals' kidneys. The entire group of organisms known as Rhombozoa—or Dicyemida—compose a full phylum of animals (as Chordata is the phylum for all vertebrates) unto themselves. Nevertheless they have only been found in the kidneys of cephalopods. Chew on that for a second; if we were to lose a little class of (albeit it really cool) animals, the cephalopods, along with it might also vanish an entire phylum of dependent critters.
These microorganisms are often unique not just to the octopus but also to a particular species of octopus. In fact, these very specific, kidney-dwelling species can even be used to tell one octopus species from another. (With such variable physical attributes, octopus specimens can be difficult to parse.)
So whether or not you ever eat octopus—whether for a feast of the seven fishes during the holidays or an adventurous summer gill out—remember you most certainly are not alone in doing so. Although many of your compatriots reproduce asexually.
Learn more about octopus parasites and all of its other oddities in Octopus! The Most Mysterious Creature In the Sea.
Illustration courtesy of Ivan Phillipsen