240 



Aquatic Organisms 



wild ducks and geese eat great quantities of duckmeat 

 (Lemna) and succulent submerged aquatics. Canvas- 

 backs fatten on the wild celery (Vallisneria). In 

 Cayuga Lake in winter they gorge themselves with the 

 starch-filled winter buds of the pondweed, Potamogcton 



Fig. 147. Floating nest of pied-billed grebe (Podilymhus podireps) in 



a cat-tail marsh, surrounded by water. 



pus ill us. They also dive and pluck up from the bottom 

 mud the reproductive tubers of the pondweed, Potamoge- 

 ton pectinatus (see fig. 228 on p. 381). 



Water birds, having attained the freedom of the air, 

 *r;\ wide anging beyond all other animals. They come 



d go annual migrations. They settle here and 



