UNDERWATER GUIDE TO MARINE LIFE 



subordination of the single cell to the life of the whole colony, a prerequisite 

 for a many-celled animal. 



This group forms the greatest of all linking groups in evolution. Not only does 

 it unite animals with plants and protozoans with sponges, but the other groups 

 of protozoans, as well as higher animals, were probably derived from flagellates. 



NootiltA.CQ. 



.. / - 



5jllCeou.s CKry^omonacl 



Cryp+on^onad "x V 





Radiolaricxrx 



Fig. 23. Protozoans. Adapted from several authors. 



The chrysomonads form a group of predominately photosynthetic planktonic 

 flagellates. They very often have a siliceous or calcareous skeleton and almost 

 always have two large, conspicuous yellow or brown bodies (chloroplasts) 

 within them which contain chlorophyll. 



The cryptomonads are oval-shaped and have a large gullet in which two 

 flagella arise. Some are photosynthetic and others ingest organic matter through 

 the gullet. None of these has a hard skeleton. 



The dinoflagellates are the largest and most numerous of the marine, plank- 

 tonic, photosynthetic protozoans and are of enormous importance in the economy 

 of the sea. The body is most often encased in plates made of cellulose, and there 

 are two flagella, one of which rests in a groove which circles the body. Ceratinni 

 is a common form in which long spines are developed as a flotation mechanism. 

 The red tide organism, Gyimiodiniuvi hrevis, occurs sporadically in tremendous 

 numbers along the coast of the Gulf of Mexico and in other warm seas. When 

 it appears, sea water is turned into a muddv, reddish color and svrupv consistencv, 

 causing a high mortality of marine life. If the temperature is high, it produces 

 a vapor that is very irritating to eyes, nose, and throat. No one knows what 

 causes sudden outbreaks of red tide. Gonyaulax causes similar damaging out- 

 breaks of "red water" in Southern California. Noctiltica is luminescent and non- 

 photosynthetic. It is large, to 1/25 of an inch in diameter, and when it is 

 disturbed by a wave, a boat, or a swimmer, will emit a sudden light. The com- 

 bined light of countless millions of them causes a beautiful, sparkling glow on 

 the water's surface. The natural color of NoctiJiica is pale pink and bv day a 

 pinkish tint may be given to the sea by them. 



All of the three groups of flagellates mentioned have some species which 



