The beroe is a most active being, its habits conforming to the organisation with which it is endowed. Such an array of paddles prophesies of a mercurial temperament and an energetic character. It can, however, anchor itself and lie by when occasion offers. It is provided with two long cables, prettily set with spiral filaments or tendrils, by means of which it can make fast to any point. When not in use, it can retract them, and stow them away in two _sacs_ or pouches within the body, where they may be seen coiled up, through the transparent walls. The mouth is a simple opening at one pole of the globular body. No arms are needed. The beroe is spared the labour and uncertainty of the chase. As it dances gaily along, streams of water, bearing nutritive particles, pass through the orifice into its stomach.
In this creature, as in many of the lower animals, there is a remarkable power of retaining vitality after the most serious injuries; nay, in portions actually severed from the body, it will continue for some time. Mr Patterson, in his excellent _Introduction to Zoology_, mentions that on one occasion he divided a fragment of the body of a beroe, lately taken from the shore and shattered by a storm, 'into portions so minute that one piece of skin had but two cilia attached to it, yet the vibration of these organs continued for nearly a couple of days afterwards!' But we must leave the beroe, charmer though it be.
Another member of this section--the _Ciliograde acalephæ_, as they are called--is the Girdle of Venus, which resembles a ribbon in form, and is sometimes five or six feet in length, covered with cilia, and brilliantly phosphorescent. This must be one of the most beautiful of the _fireworks_ of the ocean.
The jelly-fishes of another section are furnished with one or more air-bags, which assist them in swimming, and hence bear the name of _hydrostatic acalephæ_. In the Portuguese man-of-war (_Physalia_), the bag is large, and floats conspicuously on the surface of the water. From the top of it rises a purple crest, which acts as a sail, and by its aid the little voyager scuds gaily before the wind. But should danger threaten--should some hungry, piratical monster in quest of a dinner heave in sight, or the blast grow furious--the float is at once compressed, through two minute orifices at the extremities a portion of the air escapes, and down goes the little craft to the tranquil depths, leaving the storm or the pirate behind. In one species (_Cuvieria_), the floats are numerous and prettily ranged round the margin of the body. Resting on these, the creature casts about its long fishing-lines, and arrests the passing prey.