A Martian invasion? Well, maybe. There are a few scientists who think that they have found fossil bacteria in Martian space junk that has landed on Earth. These are researchers who believe in U.F.O.s (Unidentified Fossil Organisms). And, no I don’t believe that the government is hiding flying saucers and little green men down in Roswell, New Mexico. The aliens I’m interested in developed right here on our own planet and even after seeing some of them and learning a bit about them, they can still strike us as so strange as to be hard to believe in. Some, but certainly not all, of the creatures are extremophiles, that is, they live in environments which we would think could not support life–temperatures above the boiling point of water or below its freezing point, in places without oxygen, in conditions with high methane content, in conditions with virtually no water, and in areas of the ocean where the pressure is so great that we would imagine that it would crush any life form.

Earth is a planet of extremes in many senses and this is a fact that delights exobiologists. These are scientists who, based on their studies of bizarre life forms that have adapted to extreme environments, attempt to extrapolate from those, to conjecture what kinds of life forms might exist on other planets in our own solar system or even on other planetary systems in distant galaxies.

The difficulty is, of course, that our science is anthropocentric and based on an utterly fantastical, but necessary assumption; namely–that everything in the entire universe that has existed, exists now, or can possibly exist in the future is, in principle, accessible by and intelligible to human consciousness. This is the epitome of hubris and yet we couldn’t do science without it and, on the bright side, this egomaniacal view challenges us to develop our ingenuity, our powers of observation, and our imaginations in ways that can indeed extend our consciousness.

However, for us to reasonably conjecture about the possible nature of extraterrestrial life forms, we must first build an extensive base of understanding of the “alien” life forms that have and do share planet Earth with us.

Many of the most remarkable and alien creatures are ones that we rarely see. Imagine, for example, an organism that in its adult stage is primarily an egg sac which sexually neuters its host and extends thin root-like fibers throughout the body of the crab which it has taken over, these fibers extending even into the tips of the eye of the crab.

This parasite does not kill the crab, but reduces it to a feeding mechanism for itself–a kind of aquatic zombie. In order to identify this deeply weird creature, biologists had to trace it back to its larval form and discovered, astonishingly, that it is a barnacle! Anyone who has climbed around a rocky seashore very likely has an acquaintance with the common rock barnacle, Balanus, and very likely obtained some scrapes and cuts to remember them by. They belong to a group called Cirripedes and are very strange in their own right as free-living organisms, for they are, from our point of view, upside-down. The “tentacles” which extend from between the hard sharp plates of their “shell” are really their “feet” which create currents that move planktonic food organisms down into their chamber where they are digested. Then there is also the “goose neck” barnacle “Lepas” which, in the species I am familiar with, has shiny, ivory-colored plates embedded in a matrix of tough, burgundy-colored muscle. It possesses a “holdfast” which it uses for anchoring, unlike Balanus. Balanus secretes a flat or slightly curved calcareous plate which it “super glues” to rocks and pilings and which has a remarkable strength as you quickly discover when you try to pry a few specimens loose, for it is very difficult to remove them from the anchorage without breaking them apart.

For those of you who have observed whales close up or have carefully watched closeup footage in nature programs, you will likely have noticed barnacle growths on their skin. Some of these ecto-commensal barnacle species derive a triple benefit from this association in that 1) they get a free ride making them less vulnerable to predators, 2) when the whale is moving slowly or is at rest, the barnacles can use their “tentacles” (legs) to draw in planktonic food, and 3) some of these species have, like Sacculina, developed rod-like processes which extend into the skin of the whale providing them with anchorage, but also with a backup source of food which they can, when necessary, absorb from the whale itself.

Speaking of organisms which anchor themselves, we need to take a look at a bizarre sponge called Hyalonema which is certainly other-worldly in appearance.

Whoever heard of a sponge that anchors itself by means of fiber optics? These fibers are more efficient light transmitters than any fiber optics we can yet produce. There are profound puzzles here. 1) How does a colonial , multi-cellular organism produce these fibers? 2) Why would a deep-sea organism create light-transmitting fibers and why would they be of such remarkable length in relation to the “body”? 3) The tips of the fibers have tiny, anchor-like hooks, but are these sufficient to truly anchor the sponge? 4) How is the central mass of the sponge connected to the cluster of fibers that constitute this anchoring column?

Another interesting aspect of Hyalonema, as a glass sponge, is that like other species of this group, there is an interesting variety of spicules within that brownish, dried mass that constitute the remains of its body. There are, of course, hexactids, but also the distinctive dumbbell spicules.

Below are a few images of some other types of spicules found in this strange creature.

Once again, we discover that an organism that seems primitive and simple can possess an astonishing array of surprising features.

Another fairly large group of organisms that have anchors or holdfasts and looks quite primitive are the sessile tunicates. In fact, in ancient times, they were thought to be sponges and even today an amateur can easily mistake some of them for such because of their appearance. Some species, however, are sufficiently distinct as to be quite readily identifiable. Styela plicata, which my friend Mike refers to as “the chunk-of-brain” tunicates, is easily identified by its warty surface.

And Styela montereyensis which looks like brown okra also stands out since it tends to hang down from cliff faces or piers at low tide with the siphons extending downward. It must anchor itself quite firmly to accommodate heavy surfs.

One test for determining whether or not the organism in question is a tunicate is to remove it quickly from its substrate. This might result in your getting a face-full of water, since sessile tunicates are also known as “sea squirts” and can shoot out a jet of water from their excurrent siphon rather like the jet from the phony lapel flower of a clown. [I hate clowns, circuses, carnivals, parades, mud-wrestling, sports in general, dog racing and the list goes on and on. It can all be blamed on genetics, because I find the phenomena of nature much more interesting than any of those activities.]

Although tunicates may appear primitive, they are in a phylum at the top of the invertebrate phylogenetic tree, just below the vertebrates and they are sometimes referred to as urochordates. In the larval state of the sessile forms, there is the beginning of a backbone, called a notochord which disappears in the adult stage. There are individual forms, as in the 2 examples of Styela which we saw, but there are also colonies, some of which are composed of thousands of zooids. We will focus primarily on the individual forms which possess plenty of weirdness. Think of the outer layer as kind of a mantle (tunic) or “shell”, but it is one which is composed of organic materials rather than minerals ones as is the case with a typical mollusk shell. Even stranger is the fact that this tunic consists primarily of cellulose compounds which are, of course, common in plants, but rare in animals. In some species, there are tiny calcareous spicules in the tunic; however, even more surprising is that a network of “blood” vessels runs through the wall of the tunic which allows the blood to flow in both directions although not at the same time. The reason for this is the extraordinary character of the heart which is controlled by 2 “pacemakers”. The heart pumps in one direction for about 200 beats thereby draining pacemaker #1, like a battery gradually losing its charge, and then pacemaker #2 takes over, causing the heart to beat in the opposite direction and, in the meantime, pacemaker #1 is recharging itself. In some species, the blood is green as a consequence of the tunicates ability to concentrate quantities of the rather rare element Vanadium. In other words, these organisms are clearly Martians (green blood), so NASA can stop spending billions of dollars trying to find out whether or not there are life forms on Mars.

These tunicates have 2 siphons: the incurrent siphon which draws water into the pharyngeal basket which captures food and “streams” it down to the stomach. The basket is full of perforations and is rather like a miniature sack made of cheesecloth. There is a sticky mucous which forms strings that direct the captured particles down into the stomach. Undigested waste matter is then expelled through the excurrent siphon which also expels reproductive cells during breeding periods.

Once again, we are reminded of the dangers of generalization, especially when it comes to biological organisms. Certainly not all sessile tunicates have leathery, thick tunics and Ciona intestinalis is nearly transparent and one can see the general arrangement of the internal organs in living specimens. A few species are rare; a few species are regarded as endangered–mostly “edible” ones–but a fair number are regarded as fouling organisms and can occur in enormous numbers. Sometimes Styela plicata and Styela clava appear in such quantities on the bottoms of small boats that owners can spend days removing them. (A good source of specimens if you know a boat owner.)

Another peculiarity of this group of leathery tunicates is that they form a holdfast (or anchor) which is some cases is splayed to increase the potential surface contact.

Another group of bizarre organisms whose members anchor themselves is the Crinozoa which consists of 2 major orders: 1) the sea lilies or crinoids and 2) the feather and basket star or comatulids. These are echinoderms, that is, they are related to starfish, sea urchins, brittle stars, and sea cucumbers. These are ancient organisms and there are more fossil specimens of crinioids than there are extant ones and it used to be that the crinoid species outnumbered comatulids, but, in recent times, that has reversed. The specimens I have are comatulids and that’s where the discussion will focus. However, it is worth noting that the sea lilies are aptly named and some of the ancient forms had stalks up to 130 feet (40 meters) in length and sea bottoms must have looked like very strange gardens populated with these bizarre animals.

The fossil record is replete with fragments of the stems and in the samples which I have, there are 2 types that are very common 1): rings with a hollow circular center and 2) rings with a hollow pentagonal center.

The rings are relatively thick and the stalks were composed of large numbers of them stacked on top of each other. On some of them, you can see a small projection which is where, at one time, a small “arm” or tentacle extended. The holdfasts of crinoids were essentially permanent, but those of comatulids could detach and allow the organisms to be swept to another, perhaps more suitable, location where they could reattach.

Comatulids or feather stars have an extraordinarily complex “skeleton” composed of thousands of calcareous plates of a remarkable variety of shapes and sizes. Dried specimens ship fairly well but, inevitably there are some broken bits which you should collect and store for further investigation. These pieces can be transferred into a small Petri dish with some household bleach which will remove any remaining tissue and leave you with a collection of nice, white calcareous structures which you can catalog and study.

Identification is difficult because many of the major taxonomic works have long been out-of-print, so one ends up having to be content with morphology rather than classification with perhaps 1 or 2 exceptions. This afternoon, I took a small sample from an “arm” which had broken off and on a slide, subjected it to a bleach treatment. I was surprised by the number of calcareous components and took a significantly larger piece, treated it in a similar fashion and found a staggering number of bits and pieces. The entire organism which is about six inches in diameter and 3 inches tall must be comprised of tens of thousands of pieces. My sister likes to do jigsaw puzzles and so I told her I would prepare a full comatulid and send it off to her. It should keep her occupied for years. Amazingly, she was not receptive to the idea.

Everywhere we look, if we look closely, we find things that are “alien” in the sense that they are out of the ordinary and quite often very different from our initial impressions of them. So for most of us, it’s not necessary to engage in cosmic exploration to find aliens.

All comments to the author Richard Howey are welcomed.

Editor's note: Visit Richard Howey's new website at http://rhowey.googlepages.com/home where he plans to share aspects of his wide interests.

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