222 



THE BIOLOGY OF MARINE ANIMALS 



excluding larger particles (> 30^ in Oikopleura). Within the cavity of the 

 house is an elaborate collecting apparatus containing paired wings divided 

 into dorsal and ventral chambers. Water enters the ventral division on each 



Fig. 5.17. Spontaneous Squirting by an Ascidian Phallusia mammillata 



The animal was starved for 14 hours, and given food (flagellate culture) continuously 

 for 6 hours. Food added at first arrow, and stopped at second arrow. Time scale in 

 hours. (From Hoyle (47).) 



Septa 



Tube to 

 mouth 

 i 



Coarse 

 filter 



Exit 



Feedmg 

 filter 



Tail Bod y 



Fig. 5.18. Oikopleura albicans in its House 

 The arrows show the feeding currents. (From Lohmann.) 



side, and on passing through the dorsal division it is strained of all 

 suspended matter by many fine septa. This collected food material is 

 sucked into the pharynx by ciliary action. When the pressure inside the 

 house rises sufficiently, it forces open a spring door at the posterior 

 end. Ejection of water through this opening propels the animal forward, 



