Midwater Magic over the Redondo Barge

Well, not this guy.




Lately, these magnificent bulls have been lolling on the dock.








Above the barge, midwater graced us with her wonders. The bell on this lemony beauty was ~ 1 inch.








Thetys vagina is the largest species of salp. If you give one a little squeeze, you’ll find it fairly rigid, almost like plastic. That’s because the thick tunic (outer covering) is composed of cellulose.





As Thetys moves through the water, so it feeds. As it gulps along, water flows in this end…





and twenty contracting muscle bands shoot water out this end…





A filter feeder, Thetys continuously secretes a fine mucous net, which sieves the very smallest of particles from the water. The entire food-clogged net is rolled up, transported to the esophagus for consumption, and replaced by another net.





To take advantage of favorable conditions, salps have the ability to bump-up their numbers in short order. They do this by way of a form of reproduction called “alternation of generations”. This term refers to having a solitary asexual phase, alternating with an aggregate sexual phase.

At one point in the dive, I counted eight solitary Thetys and luckily spotted this one reproducing. The white structure is a “stolon”, which is producing a double chain of perhaps hundreds of individuals. Because the solitary phase is asexual, its only option is to clone itself by budding.








However, the budded, aggregate individuals are sequential hermaphrodites - meaning they have both female and male reproductive organs. Some of the individuals in the chain become females and release a single egg, which is fertilized by an older male in the chain. The baby salp is brooded and nourished within the parent until it can survive on its own. The resulting salp will be a solitary-phase animal, and can only reproduce by budding! So closes the circle.

Cyclosalpa bakeri in the asexual phase.





A chain of Salpa maxima, sexual phase.





Pyrosoma is an example of a colonial salp. Each of the little units functions just like a free-living animal, but remains imbedded in a common cylinder.




Ok, enough about salps!

Nice shots and info! Merry, just a question I have this morning (it's not on my mind constantly,) Thetys is undoubtedly quite a unique creature, but it's given name.....is it fairly recently named, and do you know anything about that naming process? Myself far away from the "Scientific Naming Agency" I was wondering if it's like naming streets, following a theme? Or was it (because of recently named?) kind of a lighthearted joking type thing? Like a scientist named "Thety" made the discovery? If not who's Thety? I know there's a whole big group of way serious scuba photographers that may not understand my question "at all!" I'd just like to know more about it is all. Thanks,

OMG beautiful photos as always and great descriptive explanations. I saw a couple of these salps last time I dove Catalina Dive Park. Amazing creatures.

I am so bummed because I have not been able to dive due to sinus trouble. UGH! On a brighter note it was great to meet you and Phil last Friday. The made my whole weekend, really. I appreciate both of your contributions to the board.

H2Ocean:

Nice shots and info! Merry, just a question I have this morning (it's not on my mind constantly,) Thetys is undoubtedly quite a unique creature, but it's given name.....is it fairly recently named, and do you know anything about that naming process? Myself far away from the "Scientific Naming Agency" I was wondering if it's like naming streets, following a theme? Or was it (because of recently named?) kind of a lighthearted joking type thing? Like a scientist named "Thety" made the discovery? If not who's Thety? I know there's a whole big group of way serious scuba photographers that may not understand my question "at all!" I'd just like to know more about it is all. Thanks,

Click to expand...

Theyts is the genus and vagina is Latin for sheath. Jeez, get your mind outta the gutter.

Hi H2Ocean,

I'm glad you asked about the etymology of the scientific name. Originally, I thought of including this in the report, but thought no one would be interested!

According to Pacific Coast Invertebrates by Wrobel and Mills, Thetys was one of the Nereids, a Greek nymph who dressed in seaweed. As Phil loves to point out, vagina is Latin for sheath or scabbard.

The yellow Narcomedusae, Aegina citrea, was named for the youngest daughter of the river god Asopus, who was abducted by Zeus. Citrea refers to the deep yellow color, citron.

Excellent photos and very, very good descriptions, thanks.

I am thanking you Sooo much for that Merry!! Although I don't have any more questions right now about it, that "thing" has just jumped on top of the list of most interesting things we're seeing down there. I did notice, just as soon as I posted this question, the "Aegina citrea, and was thinking "there might be somewhat of a theme?" I didn't know vagina was a latin derived word!! But I kind of had a blurry western'er (minds in the gutter!) idea of how "That" was given to the salp as a name!! The Thetys part is way cool! "a Greek nymph?" This is way nice! Thanks again!

I remain awed by your ability to get sharp, detailed pictures of these highly mobile, translucent creatures. And to post a photo essay that is so educational is just icing on the cake. Thank you for the effort!

I love it when you and Max post reports of your dives. They're always well worth taking the time to read.

Wow Merry! Stunning photos, superb report. The Thetys reproducing is an incredible find. I would have never thought that the Pyrosoma is a colonial salp. Many colonial salps I've seen are segmented in a way which easily identify them as being multiple individuals linked. The Pyrosoma on the other hand looks to the lamens eye as just an individual. Excellent info!