ward into the digestive cavity. The larger jelly-fishes, with tentacles streaming out to a length of thirty or forty feet, could easily paralyze large animals. It has been suggested that some of the sudden and strange disappearances of bathers may have been caused by these fearful creatures.
Hundreds of little air-pumps are employed by the star-fish. These sucking-disks upon the under side of the flexible rays enable the animal to adhere with surprising power. And it can also protrude its stomach to inwrap prey which is too large to swallow. It is thus able, by turning itself inside out, to suck an oyster from its shell; and, having an especial fondness for these mollusks, it makes great havoc among the oyster-beds.
The tongue is the prehensile organ of the univalve mollusks. Being covered with rows of toothed plates it acts like a rasp, or can be protruded beyond the head to serve as a drill. The vegetable-feeding snails have also a bony plate in the roof of the mouth to aid in cutting. The common garden-snail has not less than 28,000 teeth on its strap-shaped tongue. These mollusks, and all animals hereafter mentioned, have the superior power of vision which, enabling them to discover food or pursue their prey, is of the greatest aid in getting food. The other senses are also aids to prehension.
Fig. 3.—Common Poulpe (Octopus vulgaris).
The devil-fish, so called, the highest of mollusks, is possessor of an apparatus which for terrible efficiency could hardly be surpassed. Its prey is seized by eight long "arms" which surround the mouth, and the grasp is assured by rows of sucking-disks on the inner side of these arms. Indeed, these diminutive air-pumps hold so firmly that an arm will sometimes tear from the head. Some species have in addition two other arms equaling the body in length, which are commonly folded beneath the head, out of the way. As the creature nears its intended prey, these two long arms are quickly projected and seize the
