After learning a bit about sea cucumbers, I came away quite impressed. What a wonderfully bizarre creature! In fact, I think the platypus may have some serious competition for the title of World's Weirdest Animal.
As their name suggests, while there is variety amongst the species, most look like a cucumber that lives on the ocean floor. However, despite their moniker, they aren't plants, but are marine animals. They're echinoderms, related to starfish and sea urchins, although they don't resemble either of these.
So what's odd about them? Pretty much everything. Let's start with the brains. Oh wait, we can't--they don't have any. They do have a ring of neural tissue that helps them decide when to feed, when to move, when to fight, etc., but even this isn't that important. If this neural ring is removed, they carry on just fine. Then there's the way that sea cucumbers breathe. They lack lungs, or even gills. They extract oxygen using "respiratory trees." These organs are located inside their rear end. They intake water through the anus, and it then gets to the respiratory trees. So they breathe through their asses. But we're not done. When their fellow sea creatures try to attack and eat them, they have a strange but effective defense strategy. They expel internal organs at the would be predators, sometimes through their butt, sometimes through a tear in their abdominal wall. These projected innards are often sticky, and occasionally even toxic to the attacker. You might be wondering the obvious question, mainly, how does the sea cucumber then function without these organs? Just fine, as it turns out. They're regenerated within a few weeks.
Sizewise, again there is quite a bit of variation. They range from 3 millimeters in length to 3 meters (about 10 feet) long. Although the average size is, not shockingly, about the size of a cucumber (10-20 centimeters long). They can also live in extremely deep, pressure packed environments, as they've been found at depths of over 10,000 meters.
Sea cucumbers are mainly an Asian culinary staple, and that's where I had them. Specifically, at A La Shanghai, in Latham, NY (Thanks to Pat for the recommendation). The appearance was, predictably, strange. At first glance it resembled chunks of eggplant, but if one looked closer, you could see a blackish outer skin which had a circular pattern on it. The texture was mostly soft and chewy, although every so often there was a slight crunch at the end. Initially I found it mediocre, but it really grew on me. The more I had, the more I enjoyed it. I would definitely have this again, although I realize opportunities to do so will be limited. For the record, the other dishes at A La Shanghai were very good as well. My friends and I particularly liked the dumplings filled with soup.