PLANKTON OF THE GULF OF MAINE 
31 
To answer a question that has often been asked me by zoologists as well as 
laymen, I may remark that there is no level in the Gulf of Maine but supports a 
varied pelagic fauna. 
NERITIC AND OCEANIC PLANKTON 
None of the criteria by which the plankton can be subdivided ecologically (e. g., 
relation to temperature, season of reproduction, depth of habitat, etc.) is more 
fundamental than whether its members do or do not depend on the coast line with its 
shallows and great supply of foodstuffs; that is, whether they are neritic or oceanic. 
This distinction is as interesting to the oceanographer as to the biologist, a know- 
ledge of the mutual distribution of the two groups on the high seas often going far to 
reveal the mutual relationships and fluctuations of waters of coastal and of offshore 
origin. 
The pelagic larvae of various familiar bottom-dwelling animals (a host in them- 
selves), including most of the worms, bivalve and gastropod mollusks, decapod 
crustaceans, barnacles, starfishes, and sea-urchins, so abundant in the bays and 
shallow waters along the coasts of the Gulf of Maine, belong to the neritic category. 
The adults of many medusae, including the largest and most conspicuous species as 
well as others minute, are equally neritic, for they pass through a fixed stage in shallow 
waters during early life. Here, also, fall certain small phyllopod crustaceans (e. g., 
Evadne), which, though pelagic for most of their lives, survive unfavorable seasons 
in the form of resting spores on the bottom, a life history analogous to that of many 
diatoms, which consequently fall in the neritic category also, as do various other pelagic 
plants less prominent in the plankton. There is also a whole series of planktonic 
animals, particularly among the copepods, bound to the neighborhood of the coast 
by some unknown bond (perhaps by dependence on a particular food supply), and 
hence to be classed as neritic, although they are pelagic throughout life both as 
larvas and as adults. Here, too, must be classed the pelagic eggs of all the species of 
fish that spawn in shallow water, such as cod, haddock, pollock, silver hake, cunners, 
and flounders of sundry species. 
Contrasted with this coastwise population of the open sea are all the oceanic 
animals and plants, which are not only free floating or swimming throughout life but 
show no apparent relation to the coast line in their distribution — to borrow a nautical 
term, they form its “blue water” population. 
It is, of course, impossible to draw a hard and fast distinction between the neritic 
and oceanic categories, the border line being bridged in too many instances by the 
many pelagic forms occurring indifferently both near shore and out at sea, and also 
by animals that are dependent on the bottom in deep water at some stage of existence 
but not in shallow water; for example, by the hydromedusan genus Calycopsis, 
which probably passes through a fixed stage but has never been found nearer shore 
than the continental slope. However, the division holds fairly well for the Gulf 
of Maine. 
In northern seas, generally, n iritic elements form a large part, if not practically 
the whole, of the plankton of she tered bays and estuaries and off river mouths — 
