Walking with ambuloteuthids
{ Posted on Saturday, August 08, 2009
by Speculative Biologist
}

The walking-squid (or ambuloteuthid)


Now, this concept still has a number of problems. First, for such a muscular system to develop, it would require a complete restructuring of the squid's muscles and cartilage. And even after that there would be no guarantee that the structure of the legs would be rigid enough to support the body. Second, there are countless other species that would venture on land long before the cephalopods (the strangest of molluscs) would take that evolutionary leap. Finally, the gills and mantle may not be suitable for the derivation of lung-like structures, so the land-squids might find themselves about of breathe after they climb onto shore.

The concept of the slothsquid is basically an alternative to TFIW's elegant squibbon. This cephalopod has taken on a slow, arboreal lifestyle. Rather than being an active hunter like its marine ancestors, the slothsquid is a herbivore that uses its tentacles to grasp fruits and vegetation. The slothsquid has a few advantages over the ambuloteuthid. First of all, it doesn't need nearly as strong limbs; the rigidity needed for a terrestrial lifestyle is not nearly as necessary for an arboreal species. The highly adhesive suckers on its legs allow it to cling to branches and tree trunks. Also, the slothsquid lives in a humid, tropical environment where it would be easier for a creature with a combined gill-lung breathing system to acquire air to breathe. Still, the evolutionary probability of such a squid is not very high.
The best bet
The most likely terrestrial specialization for cephalopods is not large walking squids or climbing slothsquids. Instead, it is for small, slow-crawling octopi. Such octopi would not need to make major adaptations for terrestrial life. They would likely only need small, primitive lungs in order to breathe on land. The advantages for coming on land could vary: a way to escape predators, a way to catch terrestrial prey, or even an extra route to reach fresh breeding or feeding grounds. Such mollusc species could evolve as soon as only several million years in the future if they are to be residents of island environments. Otherwise, the horizon does not seem too bright for terrestrial squids and octopi.
3 Response to "Walking with ambuloteuthids"
Well, that's a bummer to hear that cephalopods might not advance that much on land at all. But whatever is most likely, if cephalopods were to be a little more "out-there" on land, I think they would produce lazy, arboreal forms that catch flying prey via slimy tentacles or elongate slug-like creatures. Or maybe, if they had any chance in becoming sapient, a civilization could arise from tiny, robust critters with a quasi-eusocial hierarchy.
I personaly think octopi or squids could indeed produce those small terrestrial forms, which would be kind of amphibian analogues. I have now opened more to specialised landforms though, and maybe if there was an isolated landmass without significant competitors...
I do not believe they would be "slow". Current species of cephalopods are able to move quite rapidly and even survive for periods above water.
Assuming they develop a lung, they would not need stronger legs. The arm ends might become more stubbed and have fewer suckers, but a fast low-to-ground crawler would not need much in the way of changed body shape.
A set of arms maintaining the very fine ends and suckers of current species would be the primary tools of fine manipulation.
This variant would basically "just" need lungs.
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