[海洋[DK出版社地球百科丛书]]-Ocean-(DK-Eyewitness-Books)_部分5.pdf

Shiny pearls
Pearls are produced by
mussels and oysters in
response to irritation.
Natural pearls form around
a piece of grit that gets
between the oyster’s shell
and its skin (mantle).
Tissues from the mantle
surround the grit to
produce mother-of-pearl
layers. Pearls are cultivated
Shell can
by inserting particles into a Salt pans
clam, along with some skin close to
protect When seawater evaporates, a salt-crystal
from another clam. Many crust is left behind. Large quantities of
kinds of clams produce itself from
predators sea salt are produced by flooding
pearls, but only those with shallow ponds (pans) with
shiny, inner layers to the seawater and letting the water
shell make shiny pearls. evaporate in the hot sun.
Sea salt is produced in
places with warm
weather and little rain.
The salt in seawater
is mostly sodium
chloride, but there
is also sulphate,
Double strand magnesium,
of blue pearls calcium, and
potassium.
Gloves can
be made
Noble pen shell
from byssus
grows to 2 ft
threads of
(60 cm) in length
noble pen
shell
Tapered
shell is
brittle
Silver cross inlaid
with abalone shell
Hole to expel
water and
waste
Byssus threads made
by shell to anchor it
to the seabed
Golden threads
The pen shell produces a thick mat Rainbow hues
of byssus threads to anchor it in the Inside an abalone
soft seabed of the Mediterranean. shell are all the colors
These threads were once collected, of the rainbow. The heavy
spun into fine, golden thread, and shell’s mother-of-pearl is used
then woven into cloth. Some say the to make jewellery and buttons.
cloth may have started the legend of These shells are popular with New
the golden fleece of Ancient Greek Zealand’s Maoris. Abalones are also eaten.
mythology, where the fleece was With a muscular foot that clings to the seabed,
that of a winged ram. the shells have to be