I was on my dock last week checking out the pilings and trying to figure out how many more winters I might get out of it before the need for another major renovation job, when I noticed a sea critter that surprised me by its presence because I hadn’t seen one around my dock in several years. In fact, I mentioned the absence of this creature in a Sept. 9, 2015 SlideMoor blog—Pause and Consider the Micro-World that Thrives Around Your Dock.
That is, I saw a starfish, and one almost the size of a pie pan and probably the biggest I’ve ever seen in the wild. Where there’s one there must be others, and sure enough a closer look around the pilings let me know that starfish had made a return to my dock.
As a lover of sea critters this put a smile on my face, and that evening as I recalled the sighting I realized that I didn’t really know that much about starfish. Well, Google-Dot-Com tends to make those minor lacks in our knowledge base easy to resolve, so I now know all about starfish, also known in Latinate as Echinodermata Asteroidea.
Allow me to share my newfound knowledge: As much as Echinodermata Asteroidea may be meaningless to you, its more common name makes less sense. That’s because some wordsmith years ago decided to describe this creature as a fish, even though it has no gills, scales, blood or fins, and hardly has any biological connection to fish at all.
Also commonly referred to as sea stars, starfish are related to sand dollars, sea urchins and sea cucumbers of the Phylum Echinodermata, which from the Latin means that all these creatures have a five-sectioned body plan that emanates from a central disk. Of course, given that the starfish isn’t really a “fish,” perhaps it may not really be an echinoderm, because a few of the 2,000 or so species of starfish have way more than five arms. Like say, the “sun star,” which sports up to 40 arms.
Speaking of those arms, sometimes even a common five-armed starfish might only have four or three, but that’s because starfish tend to lose their arms to predators. And not only “lose” because of predator teeth-action, but can just “drop” an arm when threatened. But no big deal, as they grow back…. Or, even more freakily, some species can even just regenerate a completely new starfish from a dropped arm (as long as it contains a piece of that central disk).
I think there’s an old horror movies that adopted this theme—“Re-Animator,” or was it “Severed Ties?”
Pardon me, as I am prone to digress, especially with regard to filmdom (or anything related to sailing).
Anyway, the reason regeneration works so well is that most of a starfish’s primary organs are located in each of its arms. Including—get this—its eyes. That’s right, at the end of each arm is an eye.
Were we just saying something about horror movie material? And no digression here, because just consider how they eat their prey—common bivalves such as clams, mussels, fish and snails: After wrapping those arms around the victim, the starfish expels its own stomach out of its mouth, which then starts digesting the prey, while sucking the digested bits back through the mouth. And then, when satiated, it just sucks its stomach back in.
And at this point you’re either thinking “Way cool!” or “gross!” I’m of the former opinion, because sea-life is just way cool, no matter how it feeds on their victims…
…or how they keep themselves from becoming victims. I already told you about the “dropped” arm trick, but most starfish are also coated with a bit of armored skin, of various degrees of prickliness, with which it helps itself fend off predators such as birds, fish and sea otters, which don’t like to feel such sensations in their respective mouths. Some starfish are a bit more prickly than others, such as the “crown-of-thorns” starfish, which is reportedly a mouthful that no creature wants to sample.
Starfish live everywhere in the world’s oceans, from the Arctic to near those super-hot deep sea vents, and from intertidal zones to deep water where no diver has ever ventured. Starfish don’t really travel very far or fast, given that their primary means of propulsion is 100s of tiny tube feet, which can only move one so far. So they rely on camouflage as another means of preventing predation.
But they aren’t perfectly camouflaged, so you should be able to spot a few around your favorite dock. That is, unless they’ve decided to take a hiatus from the area for one reason or another.
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