Tunicates Good or Bad?

[HowardE]

So these tunicates are all over the Captain Tony in Boynton Beach, FL.

What's the deal with tunicates? Are they good, bad, indifferent? Are they like a weed of the sea?

Is this photo a larval stage, and what happens when it grows up?

Thanks.

 

[archman]

Those appear to be "generic" colonial types of Clavelina, what some people like to call "lightbulbs". They don't do any damage, and are quite pretty. The more the merrier, from an ecological perspective. It's those nasty encusting compound tunicates (i.e. Didemnium) that you have to watch out for.

You have adult specimens in your photo. Larval tunicates look like teensy tadpoles, and swim around.

 

[HowardE]

People here call them blue bell tunicates... Is this correct?

What would they be classified as? in a broad, non-technical way.

 

[gangrel441]

Depends on how non-scientific you want to get.

Animals.

Invertibrates.

Most animals in their phylum are vertibrates. Tunicates are among the most complex inverts in the sea. They have a central nervous system.

The ones in your picture don't look much like the Blue Bell Tunicates in Humann's book, but they sure match the description. He uses the term "dense blue" in the description, but the pic he has in the book is more of a purple. Then again, I am partially color blind.

I would say Blue Bell is probably what you have there...

 

[archman]

People here call them blue bell tunicates... Is this correct?

I believe so. I can make up any sort of common name for a critter, and so long as I can get enough people to use it, it'll be correct.

What would they be classified as? in a broad, non-technical way.

True Tunicates. Simple Colonial Tunicates, specifically. They share a common attachment, but not extensive tissues and a siphon like the more complicated compound forms.

A lot of weenies refer to oceanic salps, doliolids, and the like as "pelagic tunicates". I don't know why they do this, when they can simply call them salps, doliolids, and the like. Ha, maybe they're just lazy.

True Tunicates belong in a different grouping within the Urochordata, and live on the bottom and attach to stuff. Most suck in water and filter out food particles, vaguely like sponges. But they're far more complicated internally. They have a heart that beats, a small brain, convoluted digestive tract, and one super-tough outer coating that's a close ringer to plant cellulose. Many species concentrate odd metals like vanadium or chomium in their bodies. They can also reverse their heartbeat, which we can't do. Cute, huh?

 

[alcina]

Arch -

That is very cool info on tunicates. I guess I am slack and have never really given them much thought beyond "ooo, pretty!"

Is there a good, user friendly book or site that gives more info on these and/or other invertebrates? I'm not looking for a highly scientific text, more along the lines of tidbits of interesting info to pass along and get people excited about more than the big fish!

 

[archman]

Hardly anyone ever asks about tunicates. What a delight to discuss them. We even have a member up in the northeast who works on some exotic form. Maybe she'll chime in with some goodness.

As for a good general reference, the Humann invertebrate guides have a decent section. Or at least the Caribbean guide does. I know my own students neglect reading it though, as it's near the back of the book. I'm sure somebody around here can name a Pacific book that has a fair tunicate section in it. The closest thing I have is Claudia Mill's book on gelatinous critters, but that only covers those bloody "pelagic tunicates".


In the Caribbean at least, a great many divers lump tunicates as sponges or corals. Some folks even think they're plants. I believe if one goes through our own ScubaBoard photo galleries, many pictures of tunicates will be found in inappropriate sub-galleries. Occasionally I write comments to have such pictures moved, and hopefully the messages are read. I wish all the invertebrates clogging up Marine Plants would be removed. They remain there, taunting me with their falsity.

 

[alcina]

Hmmm, the Humann book is tough to find here...guess I'll have to try to remember it next time some one is coming this way or next time I get back.

So far my books aren't nearly as interesting or enlightening as your post!

I like these little guys - so many varieties and interesting shapes and colours...I get asked about them a lot (as you said, mostly people thinking they are something else) it is great to have some info that is striking!

 

[gangrel441]

Hey Arch...while we are on the topic (and I know you said Pacific isn't your specialty), I snapped this shot in Costa Rica. I am fairly certain it is some form of tunicate, and they were all over the place, but I have been unable to identify it. Any ideas?

 

[archman]

Hey Arch...while we are on the topic (and I know you said Pacific isn't your specialty), I snapped this shot in Costa Rica. I am fairly certain it is some form of tunicate, and they were all over the place, but I have been unable to identify it. Any ideas?

I could swear I've seen this photo before... was it posted at an earlier date? If so, whatever we said last time would be appropriate. I remember that the consensus on that critter was inconclusive.

If this pic hasn't been posted before, it looks like a solitary tunicate... sort of. I need a closeup. It could also be a colonial tunicate (all by itself), or even a sponge. Caribbean sponges aren't usually this colour, however. The lack of any sorts of visible markings and the elongate form leans me most towards a solitary tunicate, like Rhopalaea or Ascidia. Ha, maybe it's a piece of plastic.