156 MARVELS OF FISH LIFE 



and barnacle larvae still remain (in a somewhat altered 

 form), the larvae of star-fishes, urchins, and numerous 

 others are now added to the sea. 



Thus it will be seen that in the spring and autumn 

 the sea is a mass of minute animal and vegetable life. 



In the spring the larval fish mainly feed upon the 

 diatoms, and later on in the year to a great extent upon 

 the larvae of various marine animals. 



The smaller forms of plankton life can only be 

 collected in a net with a very fine mesh, but if any of my 

 readers are anxious to examine plankton under the 

 microscope, it is not difficult to make a net of No. 20 

 bolting cloth, which can be purchased from flour milling 

 engineers. When at the seaside such a net slowly 

 towed behind a boat, will bring up many quaint forms 

 of life, but at times the main catch may be almost 

 entirely a large round protozoan, about a twenty-fifth 

 of an inch in diameter, known as noctiluca ; this, when 

 seen for the first time, may be mistaken for a fish's 

 egg. The phosphorescence in the sea on a summer's 

 night is due to these protozoa. If a spoonful or two 

 of the noctiluca be collected as described and spread 

 out on a piece of blotting paper, it is quite easy to 

 read by the light given off from them. Noctiluca, like 

 diatoms, at certain seasons increase with miraculous 

 rapidity, and by daylight may cause the sea to appear 

 of a reddish-brown colour. 



As the water in the sea swarms with plankton, so 

 the bottom of the sea is carpeted with teeming life ; 



