Page 49 - Algae

32 Algae: Anatomy, Biochemistry, and Biotechnology

FIGURE 1.48 Algal evolution and endosymbiotic events.

A number of algal groups have secondary plastids derived from those of red algae, including
several with distinctive pigmentation. The cryptomonads (Cryptophyta) were the first group in
which secondary plastids were recognized on the basis of their complex four membrane structure.
Like red algae, they have chlorophyll a and phycobiliproteins, but these are distributed in the
intrathylakoidal space rather than in the phycobilisomes found in red algae, Glaucophyta, and
Cyanophyta. In addition, cryptomonads possess a second type of chlorophyll, chlorophyll c,
which is found in the remaining red lineage plastids. These groups, which include the Heterokon-
tophyta (including kelps, diatoms, chrysophytes, and related groups), Haptophyta (the coccolitho-
phorids), and probably those dinoflagellates (Dinophyta) pigmented with peridinin, have
chlorophylls a and c, along with a variety of carotenoids, for pigmentation. Stacked thylakoids
are found in those lineages (including the cryptomonads) that lack phycobilisomes. The derivation