. The animal creation: a popular introduction to zoology. Zoology. 298 CEPHALOPODA. r%'m^ their activity and the various means that they possess of seizing and of holding then- prey, are exceedingly destructive to fishes and crustaceans around our coasts. Their prehensile arms are, in the greater number of species, provided with suckers, called " Acetabula," _ that act like . cupping- glasses. The mechanism for producing adhesion by means of these Avon- derful organs is extremely curious. From the mar- gin of each cup muscular fibres converge towards the centre, at a short dis- tance
. The animal creation: a popular introduction to zoology. Zoology. 298 CEPHALOPODA. r%'m^ their activity and the various means that they possess of seizing and of holding then- prey, are exceedingly destructive to fishes and crustaceans around our coasts. Their prehensile arms are, in the greater number of species, provided with suckers, called " Acetabula," _ that act like . cupping- glasses. The mechanism for producing adhesion by means of these Avon- derful organs is extremely curious. From the mar- gin of each cup muscular fibres converge towards the centre, at a short dis- tance from which they leave a circular aperture ; behind this is a false floor that can be raised, like the piston of a syringe, and thus produce a complete vacuum with- in the cup. So perfect is this mechanism that, while the piston continues raised, it is easier to tear away the sucker from the arm than to release its hold, but as soon as the muscular effort raising the piston ceases, the vacuum produced by its retraction is in an instant destroyed, and all the suckers detach themselves.* Few spectacles are more wonderful than that pre- * The tenacity of the gripe of the Cephalopod was fiilly appre- ciated by Homer, but the beauty of liis simile has been but little understood by his translators:— " As when the Cuttle-fish enforced forsakes His rough abode, with his adhesive cups He gripes the pebbles still; So he, Ulysses, with his lacerated grasp, The crumbled stone retained, when from his hold The huge wave forced him, and he sank ; Homer's Odyss. Book Fig. 238.—STKUCTXIRE OF SUCKERS OF Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Jones, Thomas Rymer, 1810-1880. London : Society for Promoting Knowledge
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Keywords: ., bookauthorjo, bookcentury1800, bookdecade1860, booksubjectzoology
