CLASS CTENOPHORA 
COMB-JELLIES 
HESE are delicate, free-swimming, generally spherical 
bodies, resembling jellyfishes in outline, transparency, and 
gelatinous consistency, but differing from them widely in the 
manner of locomotion. They are called “comb-jellies” from 
the rows of flat cilia, arranged like the teeth of a comb, which 
run in eight meridional lines over the surface. It is by means of 
these cilia that the animal moves through the water. The little 
paddles are worked in unison, in single lines, or each one of them 
can be moved independently, and they give the animal varying 
and peculiar motions. The Ctenophora are nearly transparent, 
but have a prismatic coloring, caused by the waving cilia, and at 
night they are phosphorescent. They are widely distributed, 
being found in all seas. 
The mouth of the animal opens into a gullet which extends 
two thirds through the length of the body. On each side of the 
gullet is a vertical tube. The two tubes unite at the base of the 
gullet, and from there run as a single canal to the end opposite 
the mouth, and open to the outside through two excretory pores. 
From the base of the gullet, where the tubes unite, two other 
tubes extend laterally, which divide and subdivide in a horizontal 
plane, becoming eight in number, and connect at the surface with 
the lines of cilia; then, dividing, run in opposite directions to the 
poles of the spherical body. The animal derives its nourishment 
and air through this circulatory system. A nervous system is 
situated at the pole opposite the mouth, in a small area surrounded 
by cilia, in the center is an eye-speck, or lithocyst. 
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