Tunicate Week: Sea Tulips.

Back to tunicates. Tunicates are sessile chordates that make everything else go "WTF?" with their sheer bizarre lifestyles. They start as tadpole-like larvae, find a place to settle down, then, umm, reabsorb their primitive spinal chords and brains. They also use cellulose to build the advertised "tunic." In fact, if they didn't eat things and have larvae, we'd be darn sure tunicates were plants.

Apparently linked to Calvinism, somehow?

...weird plants that prove that Hell is probably underwater. Yep.

Those strange, stalky things are sea tulips. Like all tunicates, sea tulips are effectively spineless vertebrates, siphoning in plankton through one hole and pushing water out through the other.  If you wish to tiptoe through the sea tulips, head to the waters around Australia and New Zealand. Sea tulips are actually among the friendlier things there, so please watch out for the other toxic fauna instead.

Sea tulips are the largest individual tunicates out there. They can get up to a meter (roughly a yard for us Americans) long. It's worth noting, however, that some free-swimming tunicates can form longer chains. For something without a true spinal cord, a meter is still pretty impressive.

Clearly the easiest underwater photograph ever. Source.

Sea tulips are symbiotic with another strange, sessile animal: the sea sponge. Many sponges, including the symbiotes present on these tunicates, have predator deterrents - bad taste, poison, and so on. Remember that both sponges and sea tulips lack teeth, so chemical defense is the best bet for both of them. These sponges also provide a lovely array of colors for your viewing pleasure.

Indeed, that seems to be the main purpose of these things: They look really neat. They also lend some credence to the ancient idea that everything on land has a counterpart somewhere in the ocean. If nothing else, sea tulips make for a neat, living bit of undersea scenery that should really be used more often. Even the fields of the sea have strange, filter-feeding flowers.

They Actually Eat That + Creature Feature: Living Rocks.

Apologies for the lack of entries. There are two reasons for it: one, vacation in Minnesota and summer in general made a mess of my schedule; two,  I've had a hard time getting motivated. No more of that! This is probably the weirdest creature I've ever seen. Behold...

Source.

...the not-so-giant rock!

Yes, that rock is alive. It's called Pyura chilensis - "piure" for short in Spanish. It's part of the extremely weird group of creatures called tunicates/sea squirts- primitive vertebrates that are free-swimming when young, then become stationary blobs as adults. In this case, the blob looks like a giant rock and lives off the coast of Chile and Peru. As with all other mature tunicates, it is a filter feeder, feeding on any microorganisms that find their way into its rocky, yet surprisingly squishy insides before squirting that water back out.

Yeah, maybe it's time for a refresher on what a tunicate is. Tunicates, sea squirts, and sea salps are, collectively, the weirdest chordates in existence. They start life as free-swimming, tadpole-like creatures with brains, spines, and other very vertebrate traits. When they mature, however, they change entirely, eating their primitive spinal chord and becoming little more than jellyfish or sponges. In this case, the piura becomes a living rock as an adult. Can it have the "best camouflage ever" award? It pretty much ate its brain for it.

Like all tunicates, the living rock is a sequential hermaphrodite. It's born male, then becomes female as it gets older.When it's on the edge of becoming female, it releases both sperm and eggs into a messy cloud in the water. Yes, the living rock can effectively mate with itself if the need arises. Consider your mind blown.

You may have noticed that this is also a "They Actually Eat That" entry. Yes, the living rock is actually edible, and quite popular at that. Peoples in coastal Central and South America are in fact quite fond of eating this tunicate. It has also taken on some popularity in Sweden and Japan. I'm personally more surprised about Sweden than Japan in this instance. It's described as being "bitter and soapy," but supposedly goes great on rice or as fried tunicate meat. Whose idea it was to break apart a rock for food in the first place

There are, however, some concerns about eating piura. For whatever reason, piura meat contains an exceedingly high amount of vanadium- look it up on the periodic chart if you've never even heard of that metal (it probably was not on your chemistry exam). The concentration of vanadium in a single rocky tunicate is ten million times that of the surrounding seawater. Vanadium has been suspected of causing liver damage in high amounts. This has not stopped people from going along the coast and picking up living rocks underwater.

This entry was so weird and strange that I may just go ahead and do a tunicate theme week...hm.. 

Creature Feature: Sea Salps.

I need to stop doing invertebrates. They have become my comfort zone. Things without spines are just so weird that it's easy to add a little more to them, make them HUGE, then send them on a rampage through Tokyo.

This is what you get for turning my kind into sushi rolls!

Here's something with a spine.

Yes, those little jelly-fish like creatures above are part of Chordata, just like you, me, and that cow in your burger. Tunicates are the most primitive of chordates, only possessing a notochord in their larval stages (if at all). The primitive structures are consumed as the organism grows; much like how one's brain turns to mush if all one does is stare at a television all day, the stationary sorts of tunicate simply do not need their brains and spinal cords. Some types are stationary, some pulse like jellyfish, and some even dwell in the abyss.

The little fellows above are called sea salps (that is not a misspelling). They start their lives as tiny, gel-bodied creatures called oozoids. One oozoid pumps out a swarm of clone-oozoids, and they form a chain as seen in the video.



One aggregated into chains, the individuals are called blastoozoids. These chains can be up to 15 feet long, and are frequently encountered around Antarctica. Luckily, salps are harmless; they feed entirely on plankton.

This would be one of the scariest sights in the world if it wanted to eat you.

Sea salps in a chain start as females, then mature into males over time. The females are thus successfully fertilized throughout the chain, allowing more jelly globs into the seas. There's a reason why tunicates are some of the most common creatures in the ocean, but that is no excuse to not study them as we would any other animal.

In fact, recent research suggests that sea salps might be slowing down global climate change. If you ignore the ads here, you might just learn something.