THE STEINHART AQUARIUM - Gulf of Guinea Science ...

subsequently grow into the familiar kelp,
which when mature sheds spores to repeat
the process.
Mortality/Longevity: Relatively few herbivores
graze directly on living kelp, abalone and sea
urchins being notable exceptions. Most of its
energy enters the food chain as detritus, bits of
dead organic matter dissolved in the water that
are taken up by a variety of filter feeders. The
plant is a perennial. Holdfasts may survive 4
to 10 years, fronds from 6 to 12 months.
Conservation Status: An increase in the
population of sea urchins, probably caused
by the indiscriminate hunting of the sea otter,
which preys heavily on urchins, may have been
a prime reason for the disappearance of large
expanses of kelp forests along the Pacific Coast
in the recent past. Now protected, sea otters
have increased in number, and the kelp forests
again cover their historic ranges.
Remarks: Kelp forests provide food and shelter
for many kinds of invertebrates and fish as well
as a few species of birds and marine mammals,
such as otters and seals. Holdfasts are home
for a variety of small snails, worms, and other
organisms.
Giant kelp is the fastest growing organism
known, adding almost .6 m a day to its length
under optimal conditions!
Kelp beds along the Pacific Coast are the most
extensive and richly populated in the world,
supporting millions of organisms representing
some 1,000 species.
RED (DIVISION RHODOPHYTA)
Encrusting Coralline Algae
Corallina spp. (Corallinaceae)
Distribution: Widespread in all the world’s
oceans.
Habitat: Common on intertidal rocky shores
and coral reefs.
Appearance: Their crustose growth form can
range from just a few micrometers to several
centimeters thick. May present a few pink to
grayish pink patches on rocks or reefs, or cover
nearly 100% of an area. Some species may be
purple, yellow or blue. The structure is hard,
California Academy of Sciences
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strengthened by calcareous deposits within
the cell walls.
Diet: Create their own food through
photosynthesis. Like all red algae, they
contain phycoerythrin, a pigment which
reflects red light and absorbs blue light. Blue
light penetrates water to a greater depth than
most other wavelengths, allowing red algae
to photosynthesize in deeper water than most
other algal groups.
Remarks: Some 1600 species of encrusting
coralline algae have been described. The
family also includes articulating corallines
(see below).
Thick encrusting corallines provide
microhabitat for a number of invertebrates,
some of which also feed on the algal film that
grows on the coralline.
Encrusting corallines are especially significant
in the ecology of coral reefs: their calcium
carbonate structure helps cement the reef
together, and they are important sources of
primary production.
Articulating Coralline Algae
Corallina spp. (Corallinaceae)
Distribution: Aleutian Islands to the Galapagos
Islands (Corallina vancouveriensis). Corallina
officinalis has an even greater distribution, and
the variety chilensis occurs along the entire
California coast and beyond.
Habitat: Corallina vancouveriensis forms dense
tufts and mats in the middle to lower intertidal
zone. Corallina officinalis var. chilensis occurs
from tide pools to the subtidal.
Appearance: Both are red (Rhodophyta) articulated
calcareous algae with pinnate branching.
Armored segments much more robust on Corallina
vancouveriensis.
Reproduction and Development: Alternation
of generations. The sporophyte and gametophyte
plants appear similar.
Remarks: Heavy calcification of the outer part
of the cell wall is an effective defense against
herbivory.
Generic name means “little coral.”
Corallina officinalis is the medicinal algae of the
ancients, named by Linnaeus for its use as a
vermifuge (to expel parasites from the intestinal
tract). Linnaeus erroneously believed the
corallines were coral-like animals.