Part 3

It is quite evident, from what has been said above, that remarkable responses to environmental stimuli are made by animals quite devoid of a brain and lacking in those sense organs popularly assumed to be necessary to such responses of the organism as have just been described.

FOOTNOTES:

See his classical work, “The Formation of Vegetable Mould Through the Action of Worms, with Observations on Their Habits,” New York, 1883.

Cf. Morgan. Prof. C. L., “Animal Life and Intelligence,” 1891; “Habit and Instinct,” 1896; “Animal Behavior,” 1900.

Shipley and MacBride, “Zoology,” 4th Ed., 1920.

STARFISH

Memory, according to Romanes, begins with the Echinoderms--e.g., Starfish, Sea-anemones, etc.; and Preyer’s extensive experiments with Starfish led him to believe that he had “discovered indubitable indications of intelligent action” in the case of Ophiurus (“brittle star”). The question is still under debate, with the weight of authority on the side of Loeb, Jennings, Gaser and others, whose experiments led them to the opposite conclusion.

Thomson finds that Starfish learn to meet new difficulties in new ways. If they cannot surmount their difficulties one way, they will try another.

Starfishes are nearly always hungry and they consider Sea-urchins a delicacy. But Sea-urchins are armed with small but sharp “three-bladed screws” on their backs. Knowing this, the Starfish deliberately strip these blades away and proceeds to devour the Sea-urchin with its elastic mouth.

Holmes observes that “the behavior of Echinoderms is certainly complex and plastic to a remarkable degree,” but he concludes that the power of forming associations in this group is very doubtful.

FOOTNOTES:

See Thomson, Prof. J. Arthur, “Secrets of Animal Life,” 1919.

SEA-ANEMONES

Some authors find evidences of intelligence in the Cœlenterata, which includes Hydroids, Jelly-fish, Sea-anemones, etc. The Sea-anemone, possessing no nerve-ganglia, when dislodged from its partnership with the Hermit-crab will quickly attach itself to the Crab’s leg and again climb up on to the back of the shell, in which the crustacean makes its “home.”

Professor J. Arthur Thomson observes that the Sea-anemone “is in some cases more than quiescent in regard to the partnership,” and adds that while responsiveness to the touch of the Hermit-crab may have come to be ingrained in its early constitution, “it is difficult to think clearly of its racial establishment.”

The behavior of some Cœlenterata, as Holmes remarks, “is often highly plastic and capable of being modified in many ways as the result of previous experience.” This is true also of the Vermes (“worms”) and Echinodermata. “We do not intend to deny the existence of intelligence in the groups mentioned; we think it not improbable that intelligence of a primitive sort may be discovered, at least in the more highly developed members of these divisions; but at the present time we can only grant the Scotch verdict of ‘not proven’.”

FOOTNOTES:

See, on this phase of the subject, Holmes, “The Evolution of Animal Intelligence,” Chapter IX, 1911.

MOLLUSKS

Among the Mollusks, not only the highly organized Cephalopods (Cuttle-fish, Octopus, etc.), but even the lowly Oyster, and the more active Snail and Slug appear to possess associative memory.

Prof. A. H. Cooke (Cambridge Natural History, Vol. III), declares that Oysters can learn from experience. Says he:--

“As soon as an Oyster is taken out of the sea, it closes its shells, and keeps them closed until the shock of removal has passed away, or perhaps until the desirability of a fresh supply of water suggests itself. The men take advantage of this to exercise the Oysters, removing them from the sea for longer and longer periods. In time this has the desired effect; the well-educated Mollusk learns that it is hopeless to ‘open’ when out of the water, and so keeps his shell closed and his gills moist, and his general economy in good condition.”

A certain degree of intelligence has been attributed to Snails. Miss Elizabeth Lockwood Thomson, for example, experimented extensively with these Mollusks and found that they are educable--that they can learn by experience.

FOOTNOTES:

Miss Thomson’s experiments are described in “Behavior Monographs,” Vol. III, No. 3, 1917, Cambridge, Mass.

OCTOPI

Schneider, Uexküll and Kollman all testify that the Octopus possesses at least a rudimentary intelligence. Romanes agrees with these authorities in attributing to this Mollusk “unmistakable evidences of consciousness and intelligence.”

“That Loligo (Octopus) and related higher Cephalopods have an extreme agility, resourcefulness, and caution is already fully recognized by naturalists, though abundant observations and experiments are still much needed,” says Prof. John Muirhead Macfarland, in his “The Course and Causes of Evolution” (1917).