setchellii has a rather unusual body form for a green alga. Unlike
most familiar green algae, C. setchellii is a crustose species,
forming a thick mat on rocks in the low intertidal zone. This green
crust comes in a variety of shades; most often the crust is brilliant
green, but in some areas of Monterey Bay the crust is dark green, almost
black in color. Crustose C. setchellii usually forms individual
round clusters on the substrate. These amorphous "blobs" in
the intertidal are often velvety in texture, varying from deep, dark
green to lighter shades of green in some individuals. The "cushion"
of the alga can reach a diameter of 25 centimeters, though individual
algae may coalesce into larger crusts over the substrate (Abbott
and Hollenberg 1976). The thallus of C. setchellii crusts
is typically 6 to 15 millimeters thick, forming a tight association
with the substrate to which it is attached (Abbott
and Hollenberg 1976).
Figure 1: Codium setchellii occurring
as a solitary round colony in the low intertidal (Point Pinos, Pacific
Grove, CA, USA)
unusual morphology appeared in individuals observed and collected from
Carmel (CA). Here, C. setchellii completely encrusted some
rocks. This unusual form had a velvet texture and formed thick and thin
mats over the rock. In some areas, the crust actually formed projections
off the main form; the function of these projections remains unknown,
but may be related to increasing surface area of nutrient uptake and
Figure 2: Unusual crust formation by C.
observed at Carmel Beach (Carmel, CA, USA) dominates the low intertidal
Similar to Codium setchellii
other organisms that live in the intertidal zone closely resemble Codium
setchellii. Some algae are similar in appearance to C. setchellii
from a distance, but only when examined up-close do the differences
some areas of Monterey Bay, the filamentous green alga Cladophora
columbiana often looks like C. setchellii. Both species
are green and have a similar globular appearance when wet. However,
the texture of Cladophora is clearly comprised of large filaments
which can be teased apart, a feature not seen in C. setchellii.
Figure 3: Tufts of the filamentous alga Cladophora
columbiana in the intertidal zone may resemble C. setchellii
from a distance
"Petrocelis" form (tetrasporophyte) of Mastocarpus
papillatus superficially resembles C. setchellii. Both
form crusts in the intertidal zone, but the crust of Mastocarpus
is dark brown in color and is much thinner than C. setchellii
Figure 4: The black crust of the tetrasporophyte
papillatus (sometimes called the "Petrocelis" morph)
one of the following links to learn more about Codium setchellii:
2005 Raúl Nava.
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