BIOLOGY OF THE SEA-HOW THEY LIVE 



37 



THIRD LtVEl -"' 



(secondary consumfrs)--^ 



SECOND LEVEL / ANIMAL PLANKTON 



(PRIMARY CONSUriERS) / (e ,. protozoa, pferopod. 

 and c«-t*^tttccans) 



SWIMMING PREDATORS 

 bony (i%h, s«a twr-H^s, 3*A snak« 



SUN 



DISSOLVED WUTRIENTS 

 { *o.l1-s and qosea ) 



SUN 



Fig. 9. A simplified food cycle of the coral reef arranged in order of energy Qfood') 

 source levels. This is a representation of the total of all the food chains in the com- 

 munity using animals from the coral reef as examples. The first level is photosyn- 

 thetic, the second level herbivorous, and the third level carnivorous. However, any 

 one animal may helong to more than one level— the omnivore which eats both animal 

 and plant matter. Bacteria may he said to constitute a fourth level since they live on 

 decaying matter. In general, the higher the level the less is the dependence upon the 

 level immediately preceding for food and the more efficient the iise of the food supply. 

 Conversely, the higher the level the greater the energy loss through respiration, a 

 fact related to the increased activity in the animals of the higher over those of the 

 lower levels. (^Adapted from Allee and others, 19S0.') 



LARGE PREDATORS 

 MEDIUM-SIZrO PRfOATORS 

 SMALL PREOATORS 



I KILLER WHALE i WH\1 

 I I SEALS » BLUEFISHJI 



\TE SHARK 

 ILARCC BASS; JACK 

 HERRING ) WRASSE J GOBICS 



ANIMAL PLANKTON 



PLANT PLANKTON 



Vig. 10. The pyramid of numbers; the higher the energy level Qfg. 9) or the farther 

 out on the food chain an animal is, the less numerous it is. The rectangular areas 

 represent relative numbers of animals. Examples are given opposite each rectangle. 



SYMBIOSIS 



The word "symbiosis" is derived from syn, meaning "together" and hios, 

 meaning "hfe" and means nothing more or less than "hving together." An 

 animal that lives with another is called a "symbiont." There are various ways, 

 however, in which animals and plants do this, ranging from nothing more than 



