Welcome to Mr Aslanov’s Lessons
QUESTION-TYPE BASED TESTS
FunEnglishwithme +99894 6333230
Pterocladia from which agar is also available. Happily, New Zealandmade agar is now obtainable in health
food shops.
Section D
Seaweeds are divided into three classes determined by colour - red, brown and green - and each tends to live
in a specific location. However, except for the unmistakable sea lettuce (Ulva), few are totally one colour;
and
especially when dry, some species can change colour quite significantly - a brown one may turn quite
black, or a red one appear black, brown, pink or purple. Identification is nevertheless facilitated by the fact
that the factors which determine where a seaweed will grow are quite precise, and they therefore tend
to occur in very well-defined zones. Although there are exceptions, the green seaweeds are mainly shallow-
water algae; the browns belong to medium depths, and the reds are plants of the deeper water.
Flat rock
surfaces near mid-level tides are the most usual habitat of sea bombs, Venus’ necklace and most brown
seaweeds. This is also the location of the purple laver or Maori karengo, which looks rather like a reddish-
purple lettuce. Deep-water rocks on open coasts, exposed only at very low tide, are usually the site of bull
kelp, strap weeds and similar tough specimens. Those species able to resist long periods of exposure to the
sun and air are usually found
on the upper shore, while those less able to stand such exposure occur nearer to
or below the lowwater mark. Radiation from the sun, the temperature level, and the length of time immersed
all play a part in the zoning of seaweeds.
Dostları ilə paylaş: