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.[7]
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.