Defense Date

6-22-2022

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Timothy Swain, Ph.D.

Second Advisor

Eben Gering, Ph.D.

Third Advisor

Chelsea Bennice, Ph.D.

Fourth Advisor

Lauren Nadler, Ph.D.

Keywords

associative and spatial learning, memory, food preference, neurobiology, marine invertebrate, animal behavior, histology, animal care

Abstract

Cephalopods and vertebrates have convergently evolved diverse adaptations such as large brains, problem-solving skills, tool use, and learning and memory abilities. These traits have been observed in cephalopods (e.g., octopus), in which they are able to solve mazes and navigate complex environments. Although there is evidence that all orders within Cephalopoda have an evolved capacity for learning and long and/or short-term memory, some appear to have less advanced cognitive abilities (e.g., nautilus) than others (e.g., octopus). The purpose of this project to determine whether the California two-spotted octopus (Octopus bimaculoides) is an example of a cephalopod with higher cognitive function, which may have evolved in response to selective pressures related to finding food and avoiding predators. This species’ cognitive ability was assessed in ~4 month old octopus using a food preference test and a learning test (ability to recognize a habitat created from 3D printed rocks and navigate to its hidden food source). Methods for determining associative learning for this species were also developed. Due to possible disinterest in the food sources and premature mortality, neither study yielded substantial insights to cognition or memory in the focal species. The octopus were observed interacting sporadically with experiment objects or hiding, a sharp contrast from the everyday interactions during husbandry where they ate once or twice a day every other day. Histology of octopus’ brains from early life stages (i.e., hatchlings and juveniles) from ages three weeks to thirteen weeks did show increased development of the optic, pedal and vertical lobes of the brain, and general overall growth and development of the brain. These results revealed full brain development as young as 11 weeks, suggesting capability for higher learning and memory. Consequently, potential enhancements to future O. bimaculoides husbandry and study design are discussed along with the possible outcomes and significance of studies into cephalopod memory and cognition.

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