The Other Invertebrate Intelligence

I won't beat around the bush in getting to what I think the second-likeliest candidate (as mentioned and discussed on Friday) for developing something resembling what we call "intelligence" is. It's spiders, hands down.

Yes, spiders, darnit.

More specifically, a large, diverse, and above all clever group called jumping spiders. Even more particularly, a genus called Portia.

But I'm getting a little ahead of myself.

Assuming that cephalopods are incapable of prolonged life on land, and that life on land is necessary to develop civilization (those are some major assumptions), we must turn to the rest of the invertebrate families.

The other molluscs? No, they're far too soft-bodied to ever achieve the kind of size they'd need for a decent brain, and far too slow-moving (mostly) to ever have the kind of lifestyle that would lead to the necessary type of brain. (The kinds that have proven able to live on land, anyway, and we're a little more concerned with them, aren't we? Nudibranchs are always surprisingly active and clever, though, compared to any mollusc but a cephalopod.) The various worms, echinoderms (starfish, sea urchins, etc.), and jellies all are rather unlikely to prove able to reach large sizes on land or to develop even a brain at all, much less a big effective one.

That leaves arthropods, who sadly have all the brains of kiwi fruit. Or do they?

The first mark in the arthropod's favor is that it's a highly mobile and active creature, as anyone who's ever had to deal with any will know. Certainly, plenty have lower-energy lifestyles, but they can easily adapt to all walks of life. And this speaks favorably for arthropods possibly developing that ephemeral trait we call intelligence.

Speaking even better for them are those most industrious and active little beasts, ants. Ants do a lot of the things we do-delegate tasks, specialize parts of their workforce (indeed, their methods of doing so are lightyears ahead of ours in terms of efficiency-they're born for their jobs), build huge mass dwellings, and more. Everything that's true of ants is also true to a lesser degree of termites (except dwellings, which they are a match for ants in the building of), and most of these are true of bees and some wasps.

But it's not really intelligence. Even if you came up with a really clever method of trying to, you could never find an ant, or even an ant colony, that could communicate with you. On an individual basis, ants are among the dumbest brained critters on Earth, and their capacity for organization is entirely on an instinctual level. (This doesn't mean that ants couldn't eventually, even following their current course, develop something frighteningly comparable to civilization that would compete with civilization of other species. I could see that happening.)

Since ants are the "smartest" insects, that doesn't leave many options. In the ocean, there's the mantis shrimp, which strikes me as being more like a housecat or a dog than possibly any other aquatic animal, if for no other reason than the ones you see in videos like the ones I've linked seem to indicate that they have a capacity for boredom, hence the sheer savagery they can exhibit in attacking their aquarium-mates. But mantis shrimps are still marine animals, and show no particular inclination towards changing that. So they're out.

But what about other crustaceans? Many live on land in various moist places. Unfortunately, they've never developed quite the same capacity for dry living as insects, so they'd always have limited ranges.

There's still the group I posited as my candidates, of course: spiders.

Why spiders?

Well, spiders (with some extrapolation from their closest relatives, scorpions) have proven to be a long-lived and versatile group. There are wandering spiders and the ever clever and tricky web builders. Web builders have poor eyesight and their lifestyles are not terribly mobile or active, mostly consisting of repeated instinctual behaviors, so despite their apparent cleverness, they do not seem to be top candidates. Wandering spiders have roving, active lifestyles, which puts them higher.

Of these, some achieve considerable sizes, such as everyone's favorite, the tarantula. While the tarantula itself does not exhibit exceptional intelligence for an arthropod, its size (and that of a scorpion from the distant past who could reach a whopping three feet in length) suggest that the size necessary for intelligence is perhaps not hopelessly distant.

Ironically, the group who shows the greatest potential in my mind are one that is invariably small-the jumping spiders. Jumpers (for whom the green jumping spider of Australia is a large variety at a whopping 12 mm) are highly mobile, have very good eyesight (only an order of magnitude less sophisticated than that of vertebrates, and better than that of dragonflies, who have the best vision of any insects), and, as their name suggests, the ability to jump.

They're the cats of the insect world. (Here, I use "insect world" in a sense that it's the world of fast, highly mobile arthropods primarily but not exclusively made up of insects. Spiders in general, by the way, are a little like the Carnivora of the insect world in my mind, although such a comparison demeans the diversity and ancient history of the spider families.) And as the insect world has no monkeys, ravens, elephants, or other similar creatures, I rate cats high.

And highest of the jumping spiders would seem to be the Portia spider. These spiders, despite brains that fit in animals that could live in houses the size of a stegosaur's infamously inadequate thought-box, show a capacity for actual learning. And not simple stimulus/response learning, either.

Portias strategize.

While many clever behaviors exhibited by these spiders are instinctual-they don't attack the spitting spider (one of the top natural enemies of jumping spiders in general) head on, for instance-many of their behaviors are devised or adapted. They are "relatively slow" learners, but map out their tactics through trial and error.

They pluck at the webs of other spiders in various ways in order to attract the spiders' attention-they may draw the spider towards what seems to be a struggling, helpless fly, only to attack the other viciously when it incautiously draws near. Or they might, in some instances, tailor their lures very narrowly: A species of Nephila spider, for instance, has a prey-sized male member. The male lives in the female's web for protection, because the female is sometimes big enough to eat small birds, and obviously is out of the prey range for even the wiliest, most vicious Portia spider that ever lived. So the Portia imitates a very small prey creature that the lady Nephila wouldn't be interested in, and the male comes running. Alone.

Somewhere, I have a National Geographic with tons of pictures and examples, but sadly all my favorite issues mysteriously disappear. Hmm...

I'll also note that the need of group behavior is no barrier to spiders either-some species build huge communal webs and swarms, and can cooperatively kill their prey and rear young.

Basically, the only relative shortcoming of spiders as potential candidates, once you get past the fact that the smartest ones are the smallest (and the general weakness of arthropods being possibly too small for good brains), is that they don't have real hands, but since they have so many other clever tools, maybe they can make up for that.

Who knows?

-Signing off.