ENEMIES OF THE CRUSTACEANS. 259 
Phyllosomas, thin as a leaf of paper, and so transparent that 
their blue eyes are their only visible parts while swimming in 
the water; and yet these flimsy creatures are nothing but the 
voung of the large and bulky Palinuri. 
Though several of the lower crustaceans ascend into the 
regions of eternal snow, while others hide themselves in the 
perpetual night of subterranean grottoes; though many delight 
in the sweet waters of the river or the lake, or rapidly multiply 
in stagnant pools, yet the chief seat of their class, which alto- 
gether comprises about 1,600 known species, is in the ocean 
and its littoral zone, where their numbers, their voracity, 
and their powerful claws, render them the most formidable 
enemies of all the lower aquatic animals that are not 
swift or cunning enough to escape them. Even the fishes 
and cetaceans are, as we have seen, exposed to their attacks; 
and as the whale, the carp, the sturgeon, the shark, the perch, 
have each of them their peculiar crustacean parasites, it can 
easily be imagined how large the number of still unknown 
species must be which feast on that vast host of fishes that has 
never yet been accurately examined. On the other hand, the 
crustaceans constitute a great part of the food, as well of the sea- 
stars, sea-urchins, annelides, and many of the molluscs, as also 
of the fishes and sea-birds; and as they are found of all sizes, 
from microscopical minuteness to the gigantic proportions of 
the Inachus Kempferi of Japan, the fore-arm of which measures 
four feet in length, and the others in proportion, so that it 
covers about 25 feet square of ground, they are able to 
satisfy the wants or the voracity of a vast number of enemies, 
from the rotifer or the polyp that feed on tiny entomostraca or 
the larvee of the barnacle, to man, who selects a great variety 
of the fat and luscious decapods for his share of the feast. 
A great fecundity enables the crustaceans to bear up against 
all these persecutions. 12,000 eggs have been found on the 
lobster; 6,807 on the shrimp; 21,699 on the great crab 
(Platycarcinus pagurus). The lower orders are still more 
prolific, for such is the rapidity with which many of them come 
to maturity and begin to propagate that it has been calculated 
that a single female Cyclops may be the progenitor in one year 
of 4,442,189,120 young! Endowed with such powers, the 
