The Elasmobranchs swallow infected molluscs or fish; pike and trout devour smaller fry; birds pick up sticklebacks, insects and worms which contain Cestode larvae; and man lays himself open to infection by eating the uncooked or partially prepared flesh of many animals.
So far as is known at present, all sticklebacks construct a nest for the reception or the spawn, which is jealously guarded by the male until the young are hatched, which event takes place in from ten to eighteen days after oviposition.
Sticklebacks are short-lived animals; they are said to reach an age of only three or four years; yet their short life, at least that of the males, is full of excitement.
Lampreys, sticklebacks, cattoids, sturgeons - the white sturgeon (Acipenser transmontanus) is commonly known as the "Oregon sturgeon" - trout and salmon are the principal anadromous fish, the salmon and trout being the most important economically.
It is now known to consist of the young fry of herrings and sprats in varying proportions mixed with a few shrimps, gobies, sticklebacks, pope-fishes and young flounders: but these impurities are as far as possible picked out from the whitebait before it is marketed.