SEA LAMPREYS AND THEIR NESTS 



325 



in color that it takes a trained eye to discover them. They hatch in about a 

 fortnight, long after the nest has been deserted and scattered by the flow 

 of the river. The larvae differ greatly from the adults; so much, in fact, 

 that they were once thought to be a distinct species, which was named 

 ammoccetes. 



The ammoccetes lie in burrows in the sand, feeding on microorganisms. 

 They live thus for three or four years before they metamorphose into lam- 

 preys. The external changes in this process consist in the development of 

 eyes, modifications in the form of the mouth, gills and of several other 

 organs. Internally the transformation is no less profound. When the 

 metamorphosis is completed, the lampreys migrate to the sea. Here they 

 live three to four years — the exact period has not been definitely ascer- 

 tained — until they reach maturity and are ready to run up streams for 

 the purpose of spawning. 



After spawning the lampreys, it appears, die, none of them returning 

 again to the sea. One may often encounter dead lampreys tangled in 

 the tall grass here and there along the river bank, where they had crept in to 

 die. There are several causes for their death after spawning, the most 

 important one perhaps being, that they are attacked by microorganisms 

 through the wounds which they have inflicted upon each other with their 

 rasping teeth while on the nest, and that in their weakened condition due 

 to the labor of tugging and transporting stones, they are unable to resist the 

 inroads of the disease and therefore soon succumb. 



Three lampreys engaged in building a nest. They root up and transfer the pebbles, 

 thus forming a circular depression some three feet across and a few inches deep. Photo- 

 graph of living lampreys on the bottom of the Nissequague River. The new group in the 

 American Museum is a faithful reproduction of this scene 



