Tool Use by a Predatory Worm

Abstract

Tool use in non-human organisms represents one of the most fiercely contested topics in animal behavior research. Tool use by an animal has been claimed to represent an evolutionarily significant jump in rational thought and ability. Here, I test the hypothesis that Diopatra cuprea are stay-at-home predators who use algae, shells, and sticks as a tool to decorate their tubes in order to serve as an advertisement for attracting prey. Diopatra are a sedentary, tube-dwelling annelid found in great abundance along the intertidal zone. These worms construct and live in long tubes, with the majority of the tube below the sediment surface and a small portion exposed above ground. They then decorate the exposed portion with three different materials: algae, shells, and sticks. To test this hypothesis, I determined what microorganisms took up residence on Diopatra tubes, analyzed the rate at which the worms rebuilt their tubes, and observed the feeding behavior of Diopatra. I found that the same group of microorganisms lived on all three decoration types, but in differing quantities. I also found that if a worm had the exposed portion of its tube destroyed by a disturbance event, it would rebuild the tube almost immediately. I was able to observe Diopatra eating off of their tubes in the laboratory setting and then experimentally determine what their likely food sources are, leading me to the conclusion that the decoration on their tubes serves as a tool for the worms and plays a vital role in their feeding behavior.