Just curious about these things

[icechip]

On a dive last Saturday came across these long strands of plant life. Usually do not see anything like this at this particular site. Maybe it is an early season growth we don't see later on? Some went towards the surface and others stretched across the bottom. Found them interesting and just curious to learn more about them.

 

[Seaweed Doc]

Is this in Maine?

On the color, would you describe it as grass-green or yellowish-brownish?

Any sense if it's hollow or solid?

How long was it?

 

[icechip]

Yes, off Rockport, Maine. Some were several feet long. Most were grass-green. They seemed fairly solid and lined with fuzz, if that makes sense.

 

[Seaweed Doc]

My knee-jerk response is the brown alga Chorda filum. However, keep in mind that I've not actually SEEN Chorda in nature. It generally grows well north of where I live on the US West Coast, though has been reported here in Washington State.

I checked with a friend from Maine, and she concurred that it was probably Chorda. (And Chorda filum is the only species of Chorda in Maine.)

Given the one photo shows them as much yellower than the "sea lettuce" in the background, I think it's probably not a green alga. "Lined with fuzz" is classic Chorda description, though if you snapped one open you'd find it's hollow. (It's pretty tough, though, as I understand.)

Chorda is a kelp, although in kind of a weird family all its own.

Common names are plentiful and inconsistent, but "Dead man's rope" seems the most frequently used common name in English.

 

[icechip]

That's pretty cool. Thank you for the information.

 

[Seaweed Doc]

You're welcome.. I'm not too useful, except occasionally I know a seaweed name!

 

[RyanT]

The other interesting thing is that despite a superficial resemblance to plants, they are not. They (the algae in general) are part of their own kingdom only sharing a distant ancestor with plants.

 

[Seaweed Doc]

The other interesting thing is that despite a superficial resemblance to plants, they are not. They (the algae in general) are part of their own kingdom only sharing a distant ancestor with plants.

It's worse than that. They should be placed across multiple kingdoms. Greens (as widely accepted) are true plants. In my opinion (though a bit more debatable), red algae are also plants. If they're not, they need a group all their own.

But browns, dinoflagellates (the algae in coral, also the cause of classic "red tides"), diatoms, etc. are totally different. They're more closely related to water molds (like the cause of the Irish potato famine) than to plants or true fungi.

Maybe I should ask PADI if they want to develop an algae diving specialty certification?

 

[RyanT]

Thanks @Seaweed Doc. I was going to make an even more general statement than I did, but a quick look at algal phylogenies revealed their evolutionary histories are indeed complex! I didn't realize that the greens were considered plants. Interesting! I would take an algae speciality course, but indeed, I don't think it would fill as quickly as something like a "reef fish ID course."

 

[icechip]

Pretty interesting that the Chorda is from its own kingdom, neither plant nor animal? Going to have to read more on this.