RE: paleonet Definition of "Algae"? (was non-green plants and Mistaken Point)

["Peg Yacobucci" <mmyacob@xxxxxxxxxxxxxx>]

Well, now this raises the issue of what it means to say "algae":

On their last midterm, my upper-level paleo students listed algae as
prokaryotes, no doubt thinking of "blue-green algae" (which are, of
course, really cyanobacteria) and those imprecisely-named "algal mats"
they've seen on sed/strat trips.

The poster below is suggesting that "algae" means photosynthetic
(eukaryotic) protists.

When *I* think of "algae" I think of a group of eukaryotic,
multicellular, aquatic, green plants.

So, paleobotanists out there, what is the proper use of the term
"algae"?

Peg Yacobucci
Assistant Professor
Bowling Green State University
Department of Geology
190 Overman Hall
Bowling Green, OH  43403
(419) 372-7982

-----Original Message-----
From: paleonet-owner@nhm.ac.uk [mailto:paleonet-owner@nhm.ac.uk] On
Behalf Of bivalve
Sent: Tuesday, October 08, 2002 2:32 PM
To: paleonet@nhm.ac.uk
Subject: Re: paleonet non-green plants and Mistaken Point

>I don't know if there are any instances of algae that can live
non-photosynthetically (if there are I would be interested...) <

Algae more or less means photosynthetic protists, so it is somewhat moot
whether one can speak of non-photosynthetic algae.  However, within the
various clades that are generally thought of as algae, there are
facultative and obligate heterotrophs.  Obligate heterotrophs may
outnumber photosynthesizers among dinoflagellates, and many of the
photosynthesizing ones can feed heterotrophically as well (which is one
reason why photosymbiotic animals get rid of zooxanthellae under
stress).  Molecular studies suggest that gain and loss of photosynthesis
has happened many times.  However, I do not know of any complex,
multicellular "algae" that do not photosynthesize.