SECTION 1. — GENERAL SURVEY OF THE ANIMAL PLANKTON 
(ZOOPLANKTON) 
Few living zoologists have been as fortunately placed as were we on setting 
sail on the Grampus from Gloucester on our first oceanographic cruise in the Gulf of 
Maine on July 9, 1912, for a veritable mare incognitum lay before us, so far as its 
floating life was concerned, though the bottom fauna can be described as compara- 
tively well known. Not but what an extensive list of pelagic crustaceans, coelenter- 
ates, and other planktonic animals had been recorded thence, but everything was 
yet to be learned as to what groups or species would prove predominant in the 
pelagic fauna; their relative importance in the natural economy* of the Gulf; their 
geographic and bathymetric variations; their seasonal successions, migrations, and 
annual fluctuations; their temperature affinities, whether arctic, boreal, or tropic; 
and whether they were oceanic or creatures of the coastal zone. We even had no 
idea (incredible though it may seem at this place and day) what we should prob- 
ably catch when we first lowered our tow nets into deeper strata of Massachusetts 
Bay, for, so far as we could learn, tows had never previously been tried more than 
a few fathoms below its surface. Nor did we at first realize, when the catch was 
examined in our floating laboratory, that the little reddish copepods (Calanus) 
darting to and fro in the glass dish, with a few large Sagittas (S. elegans ) and young 
euphausiids among them, would prove the backbone of the local planktonic fauna. 
Such, however, has proved to be the case; for station after station, cruise after 
cruise, year after year, have yielded cumulative evidence that (taken by and large) 
the calanoid copepods are its predominant members at all seasons, except where 
deposed from the leading role by the local or temporary swarming of some other 
and usually larger animal. Our first summer’s cruise was enough to show that 
Calanus Jinmarchicus (large among copepods but small if judged by more familiar 
standards) is the most important member of the plankton of the Gulf of Maine, if 
bulk and numbers both be taken into account, and that it plays much the same 
role there that it does in North European waters (Bigelow, 1914, p. 99). 
Calanus, as "red feed” or “cayenne,” is well known to the local fishermen, 
who are quite aware of its importance as food for fishes. 4 Side by side with Calanus 
we have everywhere found its relative, Pseudocalanus elongatus (p. 275) ; but even 
where the latter outnumbers the former, as sometimes happens, it adds but little to 
the bulk of the catch, so tiny is it. We have so constantly found the copepod 
Metridia lucens (p. 253), the chsetognath, or “glassworm,” Sagitta elegans (p. 308), 
the ampliipod genus Eutliemisto (p. 156), the euphausiid genera Thysanoessa (several 
species, p. 133) and Meganyctiphanes (p. 147), the pteropod Limacina retroversa 
(p. 116), the ctenophore Pleurobrachia pileus (p. 365), and (in deep water) the larger 
copepod Euchfeta (p. 230), associated with Calanus, that all these together may be 
spoken of as the “ Calanus community” (figs. 10 and 11), a community that domi- 
nates the animal plankton from the Grand Banks on the north to Cape Cod (in 
winter even to Chesapeake Bay) on the south, and from the coast line, on the one 
hand, out to the continental slope, on the other. 
* See page 188 for a further account of this copepod. 
16 
