PLANTS OF THE SEA 83 



Columbus in 1492. It lives and breeds on shores in the Caribbean, but breaks off 

 during storms, becomes pelagic, floating in clumps, and is carried to the Sargasso 

 Sea between the Bahamas and Bermuda by the Gulf Stream where it propagates 

 by fragmentation. It forms the basis of a fauna all its own (Chapter 1). The 

 mermaid's fishline. Chorda, is well named for its ropelike, unbranched strands, 

 which reach 15 feet in length. Beds of this alga are sometimes very extensive 

 especially on the East Coast. Chorda is an annual, growing each spring. 



The various kelps are the largest of algae and among the largest of all plants. 

 The immense beds of kelp are especially well known on the West Coast. They 

 can be dangerous to swim in, the long, very tough tendrils easily snagging the 

 swimmer or his equipment. They harbor a great number of fishes as well as 

 the famous and rare sea otter. Some kelps, however, are small and live in tidal 

 zones. The tvpical kelps or devil's aprons belong to the genus Latninaria. They 

 reach 15 to 20 feet in length but are usually seen much smaller. The wide, flat 

 blades are typical. In the common species, these blades are single, but other 

 species may have several blades rising out of a single stipe (stem). Other kelps 

 are the bladder kelp, Nereocystis, which is found in waters up to 100 feet deep 

 and grows best on shoals or rocks near active waves or currents; the sea colander, 

 Agariim, a seedy-looking plant with a perforated blade, which grows up to 5 feet 

 long in the north temperate Atlantic; the sea pumpkin, Pelagoj)hyciis, which 

 is a large kelp found from Santa Barbara to Baja California; the vine kelp, 

 Macrocystis, which is the longest of all algae, with a length of up to 200 feet. 



Lessionopsis is a verv bushy brown alga which reaches 6 feet in length. It 

 grows on rocks exposed to surf and is found only on the West Coast from 

 Alaska to Carmel, California. Alaria is large, sometimes up to 15 feet or more in 

 length. It has a prominent midrib and a group of small blades near the base of the 

 stipe. It is found on both coasts, mainly in colder waters. The sea palm, Postelsia, 

 is a very odd alga which grows on the West Coast in shallow waters where it is 

 exposed to the full force of the waves. Padina, the peacock tail, is a leathery, 

 funguslike form found in the tropics. It grows to a few inches in height. 



Some brown algae are of considerable economic importance. Gelatin and the 

 filler used in cheap ice creams come from them. They are widely used as food, 

 especially in the Orient. 



RED ALGAE: Phylum Rhodophyta— F/^wr^ 22 



It is often stated that red algae are adapted better than other algae for life in 

 deep waters. It would be perhaps better to substitute "intermediate" for "deep," 

 for these algae are able to utilize not the light of shortest wave length, the blues, 

 which most deeply penetrates the water, but rather the light of intermediate 

 wave lengths, the greens. Red algae possess the accessory pigment phycoeryth- 

 rin, which imparts a red to deep purplish color to the plant. Sometimes the 

 color may be orange or olivaceous. Phycoerythrin absorbs the light which is 

 almost exactly complementary to that absorbed by green algae. The greens of 

 the spectrum are most efficiently used by red algae, while reds and blues are 

 not of much use. Therefore, red algae tend to replace green algae in water 

 over a few feet deep and are found in waters to 100 feet or more in depth. 

 They are most common, and most efficiently photosynthetic, at 15 to 50 feet, 

 the depth where green light predominates and red light is weak. 



