(And also when you haven’t got a choice…)
Meet the humble coco worm (aka “fan worm,” aka “tube worm”). I have seven. Three have names –
(Named for the fact that his tube is four times the length of the others. If you don’t get the reference, I can add another name to the list of people less geeky than me. If you do…welcome to the Sci-Fi Geek Club. Always room for one more.)
The worms themselves are hidden in the long curving “tubes” – which the worms make to hide and protect themselves. The tubes are mostly calcium and detritus (don’t ask) and the worms add to them whenever they need more room. The colored projections at the top are feeding cones. The worms filter particles from the water to eat and to build their tubes. If anything gets near them when the cones are out, the cones disappear completely into the tubes almost too fast to see. Even a shadow will usually set them off.
For months, the worms inhabited the tank without incident. The cleaner shrimp, Phobos and Deimos (recently joined by the smaller Io and Europa) harass them occasionally when bits of food get stuck in the worms’ feeding cones, but for the most part everything leaves them alone.
About a month ago, however, I brought home a pair of seahorses (Cygnus and Sputnik). The little guys were raised in bare-bottom tanks and they had never seen a reef. Many entertaining hours ensued as they ogled just about everything and grabbed like hungry toddlers at a bake sale. Anything and everything was a target for grasping tails – including the unsuspecting tube worms.
The first few times the worms pulled in, leaving the seahorses startled and holding only water. (Cygnus tended to rest his weight on whatever he hitched to, so he frequently fell to the bottom when the worms disappeared beneath his grasp.) We laughed, and the seahorses swam off to find another hitch.
But seahorses are persistent little devils, and eventually they managed to grab hold without scaring the tube worm off. To my surprise, the feeding cones stayed extended and the seahorses “rode” the cones like a hitching post. They do it constantly now, and the worms rarely object.
I attribute the change to the tolerance of one species and the intelligence of the other. Over time, the seahorses learned that rapid motion and crushing grasps made the worms retreat. They approached more slowly and gripped only tightly enough to secure a hold. They also wind their tails through the feeding cones gently, as though making the worm aware of their presence before they wrap themselves around and hitch.
The worms learned the seahorses wouldn’t harm them and now tolerate the horses’ constant “hugs.” When the worms have had enough they pull away and the horses move down to hitch to the tube instead and the worms re-emerge – the point is made.
Two more life lessons learned in an artificial sea. If at first you don’t succeed, approach with caution and think the problem through. Eventually you may find a way to reach the desired goal. Also, we can accept a lot more than we think if we put our minds to it. (Or whatever passes for a mind in the body of a worm.)