4-8 Memoir Sears Foundation for Marine Research 



caudal brush-shaped, with rounded corners, extending forward on ventral side of trunk for 

 a distance about as long as base of ist dorsal j no separate anal fin; anus anterior to ventral 

 origin of caudal by a distance about % as long as base of ist dorsal. 



Color. Small specimens, whether on their way downstream or in salt water, are white 

 below and uniformly colored above, usually described as blackish-blue or lead-colored and 

 as more or less silvery." But large specimens, approaching maturity, are usually olive- 

 brown above, or of varying shades of yellow-brown, green, red or blue, mottled with a 

 darker shade of the ground color, although sometimes nearly black, the dark patches con- 

 fluent; lower surface whitish, gray, or of a pale shade of the same hue as ground color of 

 back. During the breeding season, at least in the landlocked form, the colors become still 

 more brilliant, with the ground tint described as turning bright yellow. 



Size. The length, at the time of transformation, ranges from about lOO to 200 mm. 

 Sexually mature specimens, taken in American rivers, average about 2 to 2 V2 feet in length, 

 the largest of a considerable series from the Navesink River being 33 inches long, weighing 

 two pounds, four ounces; the maximum recorded length is about three feet. 



Developmental Stages. The eggs are small, spherical. A female has been found to 

 contain 236,000 ova. Segmentation is total, but slightly unequal. The larvae, which differ 

 widely from the adult in external appearance and habits, as well as in internal morphol- 

 ogy, are described above (p. 45). 



Habits. Since Lampreys never take the hook and are seldom captured in nets, except 

 close to the beach in pound nets or in estuarine situations with shad nets, they are not often 

 seen in the open sea; consequently, little is known of their habits in the sea, except that they 

 are rapid, vigorous swimmers, progressing by an undulating motion, as does an eel, and 

 that they are exceedingly aggressive in their attacks on other fishes. Occasionally they are 

 found attached firmly to driftwood and even to boats. 



The fact that Lampreys, when encountered in salt water, are usually close to 

 the land or even in estuarine situations, suggests that most of them remain in compara- 

 tively shallow water during their sojourn in the sea. But some stray far offshore and 

 descend to considerable depths. Odd specimens have been caught on the Grand Banks at 

 86 fathoms north of Emerald Bank; on the seaward slopes of the Nova Scotian Banks off 

 Nova Scotia, at 200 to 350 fathoms;"" at 85 and at 100 fathoms on the western side of 

 the Gulf of Maine; at 247 fathoms off Martha's Vineyard and at 547 fathoms off Nan- 

 tucket, Massachusetts. 



The geographic range of the species, combined with observations on the vertical dis- 

 tribution of temperature at different seasons, shows that it is tolerant of a wide range of 

 temperature. It is equally tolerant of salinities ranging from fresh water to that of full 

 oceanic saltness (3.5 per cent or even more). 



The normal food of the Sea Lamprey is the blood of other fishes, which it attacks 

 by sucking with the oral disc. Usually the Lamprey fastens to the side of its victim, where 



59. Those that we have seen have lost all color in ...e preservative. 



60. Specimens in the U.S. National Museum. 



