Researchers in the Crook Lab come from diverse educational backgrounds and have many different career goals.  

PrincipAl Investigator

Dr. Robyn Crook 

I am an evolutionary biologist and behavioral neuroscientist. I received my undergraduate degree in Zoology at the University of Melbourne, Australia, in 2004. I moved to New York City to complete my Doctorate in Biology (Ecology, Evolution and Behavior) at the City University of New York. After developing an interest in how selection on behavior shapes the evolution of brains, I took a cellular neuroscience post-doc at the University of Texas Medical School at Houston in 2008. I started here at SF State as an Assistant Professor in 2015. My research lab's primary focus is the evolution and function of injury-induced behavior, including pain. My students work mainly on the model organism Euprymna, but also on octopuses and other squid species as pertinent questions arise. 

In addition to running my research lab, I teach undergraduate and graduate courses in the Physiology major and P&B Masters programs.  My current teaching assignments are Human Physiology Lab in the Fall, and Neural Systems Physiology in the Spring.

Lab Members

Masters students


Meghan Holst (Class of 2020)

I am a Masters student in the Physiology and Behavior program at San Francisco State University. I am also a biologist at Aquarium of the Bay in San Francisco. 

For my Master’s thesis, I am interested in studying the decline in Giant Pacific Octopus (GPO’s),Enteroctopus dofleinias they go through senescence (terminal reproduction).

Similar to salmon's reproductive life cycle, cephalopods undergo major physical deterioration during this time. Senescent octopuses have a myriad of symptoms that vary from each individual, but always include anorexia, deterioration of the skin, sinking of the eyes, and stereotypic repetitive behaviors. As octopus slowly decline and deteriorate, facilities housing them question how ethical it is to allow animals to experience extended terminal decline. However, it is currently unknown how octopuses experience senescence physically and mentally.

I hypothesize that as GPO’s decline, their nervous system also declines. The nervous system is responsible for sensing stimuli from the environment and sending this message to the central brain. If the nervous system is degrading, I hypothesize that GPO’s ability to sense stimulus will decline. To test this, I am measuring how GPO’s respond to the same stimulus over time. I expect that GPO’s will have a decrease in stimulus response as they continue through senescence until eventual death. Understanding how GPO’s perceive their environment and translate stimulus will the be first step towards understanding how they experience senescence. This research will produce information critical for making ethical welfare decisions of octopus on display or in lab settings worldwide. 

 I am collaborating with multiple aquariums across the country to study captive GPO’s. It is my intention that through collaboration, our industry will have a better understanding of senescence in GPO’s and how their deterioration may influence their well-being. 

Upon receiving my M.S. in Physiology and Behavior, I plan to complete a Ph.D. that will complement the research I conduct at Aquarium of the Bay. Research conducted with SFSU and a future Ph.D. program will contribute to Aquarium of the Bay’s mission to protect, restore, and inspire conservation.


Stephanie Bazarini (Class of 2019)

I’m a Masters student in the Physiology and Behavior program at SFSU.

I'm interested in the physiological factors that pre-dispose women to chronic pain, particularly how fluctuations in female reproductive hormones can affect neural sensitization. I am using the Hawaiian bobtail squid as a comparative model to examine whether estrogen influences nociceptive sensitivity after injury.  The females of this species express estrogen receptors, but do not undergo estrous cycles like mammals do.  

I am exposing groups of injured and uninjured squid to either no, chronic, or acute doses of estrogen in tank water and comparing neuroanatomy, behavior and neural excitability among the treatments. The estrogen exposures are designed to either replicate the effect of chronic environmental exposures throughout development or to mimic the interaction of an acute estrogen peak co-incident with inflammation. I hypothesize that estrogen exposure increases estrogen receptor and dendritic spine density in developing brains, and greater behavioral and neural sensitization after injury. However preliminary data suggests that estrogen-exposure reduces neural responses to injury.

My hope is that this work will increase our understanding of conserved mechanisms of estrogen/injury interactions and provide new insight into existing mammalian pain studies. Additionally, this work will improve our knowledge of the effects of environmental estrogens.

My goal is to earn a PhD in a Neuroscience program where I can continue to research the role that steroid hormones play in disease states that disproportionately affect women.

I have taught the BIOL 230 (Introductory Biology for Majors) Lab class for three semesters and really enjoy getting to share my love for biology with students at the beginning of their university careers. I have also worked as a GA for the Neural Systems (BIOL 642) and Hormones and Behavior (BIOL 622) classes. I am very honored to have been selected as and ARCS (Achievement Reward for College Scientists) scholar for the 2018 – 2019 academic year.

Stephanie is funded by the ARCS Foundation Scholarship program.


Ryan Howard (Class of 2019) 

I’m a Masters student in the Marine Biology program at SFSU.

 Research experiences in the Great Barrier Reef and along the Costa Rican coast introduced me to cephalopods and their breathtaking rapid adaptive camouflage. Pursuing research to understand this complex behavior led me to the Crook Lab where I study how minor tissue injury to their adaptive skin affects camouflage behaviors of Indo-Pacific octopuses. 

Adaptive camouflage has evolved independently several times both in terrestrial and aquatic species, and though it’s a widespread defensive strategy, little research exists explaining how organisms compensate when superficial injuries disrupt camouflage patterns. Octopuses are phenomenal model organisms for studying this dynamic because of their ability to adjust their camouflage displays in less than a second. 

My research is focused on determining the roles nociceptive sensitization and visual self-referencing play when octopuses make camouflage decisions after being superficially injured. By creating sham and true superficial injuries I can regulate which sensory input mechanism is accessible to the study subjects. I’m then able to quantify the camouflage components (e.g. color and luminance) and compare treatment groups with image analysis software. I hypothesize that octopuses utilize sensory input from both nociceptive sensitization and visual self-referencing to influence their camouflage behaviors. 

This project is designed to provide insight into the sensory mechanisms utilized by octopuses for implementing their complex camouflage behavior. My hope is that this research will produce significant findings that will inspire researchers to ask similar questions in other model organisms that uses adaptive camouflage.

I’m honored to be a NIH MA-MS/Ph.D. Bridge to the Future Fellow while earning my M.S. degree from SFSU. After graduation, I’m committed to continuing my education in an Ecology and Evolutionary Biology Ph.D. program, where I plan to study cephalopod behavior and ecology.  My ultimate goal is to actively support underrepresented groups achieve their dreams of becoming STEM researchers by partnering with organizations such as the Society for Advancement of Chicanos/Hispanics and Native Americans in Science (SACNAS). 

Ryan is supported by an NIH-Bridge Fellowship.


Vivien Enriquez (class of 2019)

I am master's student in the Physiology and Behavior program at SFSU. 

With a diverse background in biological anthropology, wildlife conservation, and animal behavior my graduate research explores questions related to how microorganisms influence characteristic animal host behavior and survival. Microorganisms, such as bacteria, viruses, and fungi dominate the natural world in terms

of sheer abundance and are consistently offering new insight into their role in animal development, health, and behavior. 

Using the Hawaiian bobtail squid-Vibrio fischeri model, I am investigating how the bioluminescent, bacterial symbiont (Vibrio fischeri) impacts a suite of host behaviors, such as swimming and foraging, and survival throughout multiple stages of the squids' development. To examine these impacts, I am conducting behavioral observations through experiments that manipulate the colonization process by rearing squid in the presence or absence of V. fischeri

Completing this research will add to our existing knowledge about this rigorously studied model system and will provide insight into how V. fischeri may offer more to its host than bioluminescence. I hope the completion of this study will serve as a jumping-off point for additional research questions which tackle the mechanisms behind why bacterial symbionts may be key for host survival. 

Upon receiving my M.S. degree from SFSU, I plan to continue my studies in animal behavior and host-symbiont interactions by completing a Ph.D. program in Ecology and Evolutionary Biology.  I am thrilled to have conducted my research in the Department of Biology at SFSU as an NIH Research Initiative for Scientific Enhancement (RISE) Fellow and California State University Sally Casanova Pre-Doctoral Scholar. 

Vivien is funded by the NIH-RISE fellowship program.


Karen Bueno (class of 2018)

I am a Master's student in the Physiology and Behavior Program at San Francisco State University. I received my Bachelor's degree in Zoology from SFSU in 2013.

My thesis project seeks to understand how environmental stressors such as elevated seawater temperatures might affect nociception in cephalopods and other intertidal and subtotal species.

Karen is funded by the NIH-RISE fellowship program.


Undergraduate Students

Undergraduates can receive class credit for their research internship by applying to be admitted to the BIOL699 course, 'Special Study in Biology'.

Spring 2020

Amirah Burleigh

Timothy Balilo

Alan Fallahi

Ichigo Zachau


Crook Lab Alumni


Hanna Butler Struben - MS Biology (Physiology and Behavior).

Nasira Johnson - BS Marine Biology

Ana Martinez - BS Physiology

Joseph Abdelmessih - BS Physiology


Samantha Brophy - BS Physiology. Now Research Specialist, Gladstone Institute, UCSF

Emily Zepeda - BS Cell & Molecular Biology. Now PhD Candidate, UC Davis

Robert Veline - BS Physiology. Now Research Specialist, UCSF

Katherine Stennette - REU BREED student.

Sara Tom - BS Physiology

Lemo Dayekh - BS Physiology

Penman Bastani - BS Physiology

Robert Dasmarinus - BS Physiology

Sugar McQuarn - BS Physiology


Kia Seehafer - REU BREED student. Now PhD Candidate, U. Minnesota

Paul Perez - BS Physiology. Now Senior Research Associate, Genetics core, UCSF

Christina Lardie - BS Physiology. Now paramedic, Sacramento County Fire Dept.

Lauren Lopes - BS Physiology. Currently at San Francisco General Hospital

Joshua Hernandez - BS Physiology

Stephanie Skidmore - BS Physiology