Investigating sentience and emotional states in wild octopuses: Michaella Pereira Andrade, Charles Morphy D. Santos, and Tatiana Leite

Michaella Pereira Andrade will use Wild Animal Initiative funding to perform a multifaceted study of juvenile wild octopuses (Octopus insularis). Photo credit: Tatiana Leite

December 12, 2022

This year marked a significant milestone for octopuses and other invertebrates — the UK government passed a bill recognizing crustaceans and cephalopods as sentient. Science played an important role in this legislation getting passed, thanks in part to a 2021 literature review by prominent sentience researchers who examined more than 300 scientific studies on invertebrate sentience. Ultimately, the review recommended that “all cephalopod molluscs and decapod crustaceans be regarded as sentient animals for the purposes of UK animal welfare law.”

The term “invertebrates” includes a diverse spectrum of animals, and the evidence for their sentience varies widely across groups — and even within groups. Very little research exists to support sentience in clams and mussels, while a sizable body of research supports sentience in cephalopods, which branched off from other molluscs hundreds of millions of years ago.

Octopuses are so biologically strange that astrobiologists study them as a model for alien life, and they seemed to have evolved sentience independently of vertebrates and of other invertebrates. Sentient animals can have positive and negative experiences, and we’re only beginning to understand how we might assess welfare for sentient invertebrate species, including octopuses. Their stark differences and separate evolutionary path from other invertebrates make them both challenging and exciting to study.

“The science on welfare for wild octopuses is still in the nursery, so to speak,” says Michaella Pereira Andrade, a PhD student studying Evolution and Diversity at Federal University of ABC (UFABC) in São Paulo, Brazil. With her advisors Tatiana Leite and Charles Morphy D. Santos, Andrade will use Wild Animal Initiative funding to perform a multifaceted study of juvenile wild octopuses (Octopus insularis). 

In the South Atlantic Ocean’s Rocas Atoll and two other sites off the coast of Brazil, the team plans to investigate emotional states in young octopuses, looking for individual variations in their behavior and scoping potential welfare indicators. Another aspect of the study will model evolutionary trees for octopuses to understand when sentience evolved in cephalopods. 

WHY WE FUNDED THIS PROJECT

We are interested in variations in animals’ sentience so that we may estimate their capacity for welfare and the quality of their lives in the wild. Understanding which animals are sentient at which developmental stages is therefore foundational to our work. This project is especially interesting because it will teach us a lot about what the lives of juvenile octopuses are like and the extent to which welfare impacts are mediated by personality traits.

Evolution, sentience, and welfare

“We know very little about how octopuses express their emotional states through their behavior, and studying this can help us know how to evaluate their welfare in the wild.”

—Michaella Pereira Andrade

Photo credit: Tatiana Leite

Long before Andrade knew that sentience and welfare were topics she could study scientifically, she spent her childhood fascinated by the inner workings of animal minds. Her curiosity about animal lives ultimately brought her under the mentorship of Leite, a professor and cephalopod researcher at the Federal University of Santa Catarina in Brazil, and Santos, an associate professor of comparative and evolutionary biology at UFABC.

This will be Andrade’s first time studying octopuses in the wild, and she’s excited to build on Leite’s decades of work on cephalopods. This research is part of the 25-year-long Cephalopod Project in Brazil, which Leite helps to coordinate. The species they will study, O. insularis,  lacks an established common name because of its recent discovery in the early 2000s by Leite and her colleagues. In a forthcoming book, they plan to call it the “stout reef octopus.”

“I think invertebrates are particularly interesting, maybe because people have historically looked down on them in terms of welfare and sentience,” Andrade says. “We know very little about how octopuses express their emotional states through their behavior, and studying this can help us know how to evaluate their welfare in the wild.”

To investigate the evolution of sentience in the first part of her project, Andrade will use previously published morphological and genetic data on molluscs to model when traits potentially associated with sentience likely emerged in the ancestors of octopuses. Andrade will employ a phylogenetic approach known as ancestral state reconstruction, which uses advanced statistics to enable scientists to estimate how evolutionary processes unfolded across time and explore how certain traits, such as nervous and sensory system features related to sentience, may have evolved. The analysis will also take into account traits that are present or absent in larval life stages to define the characteristics of sentience.

“When we study the evolution of traits related to sentience, we can understand the pattern and distribution of these traits,” Andrade says. “Only sentient animals have welfare, and [these traits] can help us understand which groups of animals are possibly sentient so we can look for welfare metrics in other animals.”

Approaching the topic from a comparative biology perspective can help us reframe our understanding of sentience not as an “evolutionary step before the emergence of the human phenomenon but as a variable and essential natural feature,” Santos says. “Furthermore, recognizing the vast plethora of possibilities of sentience may modify our perception of the vastness of the animal kingdom, which is a condition to reinforce the support for wild animal initiatives.” 

Octopus emotions

Andrade will observe juvenile wild octopuses living off the coast of Brazil. Photo credit: Tatiana Leite

For the field portion of the project, Andrade will observe juvenile octopuses living in the wild at three locations off the coast of Brazil. The first, Rocas Atoll, is a remote, ring-shaped island rich with coral and other marine life. The ring protects the waters inside the island, making it an ideal location for vulnerable planktonic octopuses to grow. 

Young octopuses who inhabit the shallow waters in the atoll take shelter in dens until they’re old enough to move into open water. The other two study sites include a national park with a tourist beach and a fishing location. These locations will provide opportunities to contrast challenges that juvenile octopuses face in different environments. 

Studying animals in the wild can yield insights about animal behavior that are difficult or even impossible to observe in captive settings. For example, Leite has observed that octopuses in the lab display a narrower range of chromatic changes than they do in the ocean. Color fluctuations could indicate an octopus’ internal state, hinting at one possible way to measure welfare in cephalopods.

As part of her field work, Andrade will set up cameras near each juvenile octopus den she discovers, giving them time to habituate to the camera equipment. So far, researchers haven’t identified a reliable, noninvasive way to keep track of individual wild octopuses, so Andrade will depend on juvenile octopuses’ tendency to return to the same den. She’ll also take note of any unique physical features the octopuses may have, such as markings or injuries.

From there, she will introduce a series of objects to each octopus, watching them interact with the object for about five minutes. Objects will vary from a plastic toy crab to a PVC tube and a simulated predator. Though she will observe the octopuses on site in real time, the cameras will capture how they react so she can later assess different aspects of personality, including boldness and activity level. 

Just as individual people may have different reactions when presented with an interesting object, Andrade hypothesizes that the octopuses will react in varying ways dependent on their personality traits, and these variations could impact how we might assess welfare in cephalopods. Andrade will repeat the tests multiple times on each individual. Leite’s 20 years of experience with similar experimental methods will help ensure minimal negative impacts to the octopuses from these interactions.

“These tests were chosen to help us better understand how the octopuses might express their emotional state and how individuality might impact these states,” Andrade says. 

She plans to compare these experimental reactions with observations of octopuses in the wild participating in activities that are likely to indicate a negative or positive emotional response, such as eating, resting, or escaping from predators. Andrade and her team will also review the camera footage in detail to code and assign reactions and behaviors.

Cephalopod welfare

Countries around the world are only beginning to recognize cephalopods and other invertebrates as sentient. Photo credit: Tatiana Leite

Andrade’s investigations of octopus emotions are laying groundwork for future studies on wild octopus welfare, she says. An animal may be capable of having positive and negative experiences, but until we know how to measure their emotional states, we can only make educated guesses about their welfare. If Andrade observes the same specific behaviors, body patterns, or physical indicators each time a juvenile octopus has a stressful experience, this may provide clues about their well-being. 

As the UK sentience bill shows, countries around the world are only beginning to recognize cephalopods and other invertebrates as sentient. In Brazil, which has a robust octopus fishery, Leite hopes this research could lead to better welfare laws for cephalopods to reduce their suffering. Brazilian universities and scientific institutions also don’t consider cephalopod welfare for experimental purposes, so Leite would like to see this research lead to a shift of perspective in academia, as well.

From a scientific perspective, Andrade says she appreciates the challenges posed by studying welfare, particularly for invertebrates. If we can learn how wild octopuses express their emotional states, she says, it brings us one step closer to measuring their welfare.

“One of the most exciting things about wild animal welfare research,” she adds, “is that there’s still so much more to learn.”

RELATED RESEARCH

Leite coauthored a 2011 paper on the habitat, population density, and diet of O. insularis in Rocas Atoll : “Atol das Rocas: an oasis for Octopus insularis juveniles.” This 2021 paper by Andrade et al. explores the evolution of sentience: “What if… sponges originated 890 million years ago? On the emergence of some precursors of animal sentience.”

Andrade’s proposed study is funded by Wild Animal Initiative’s Grants Program. This is the seventh and final story in a series of features on our spring 2022 cohort of grantees. Please subscribe to our newsletter to get future stories delivered straight to your inbox.