Mysterious Morphology: An Investigation of the Octopus Keel and Its Association with Burrowing.

The octopus keel is a trait that has been hypothesized to be connected with burrowing in octopuses, but has never been explored in any detail. We investigated the association between these two traits using two approaches. First, we examined the phylogenetic correlation between the presence of a keel and known burrowing behavior in cirrate octopuses. Second, burrowing and non-burrowing captive Muusoctopus leioderma were evaluated for keel prominence to determine whether the keel is lost more rapidly in non-burrowing individuals. Pagel's test for the coevolution of binary characteristics showed the model of best fit for the resulting phylogenetic tree to be one of evolutionary interdependence, and that non-burrowing Muusoctopus leioderma lost their keels over time, while burrowing individuals maintained their keels. Together, these results indicate the keel may be a trait associated with burrowing in octopuses.

The Open acidification Tank Controller: An open-source device for the control of pH and temperature in ocean acidification experiments.

Ocean acidification is the process by which the increase in atmospheric CO2 causes a corresponding increase in seawater CO2 and results in lowering the seawater pH. While this process is likely to have substantial impacts on marine ecosystems, research into the effect of ocean acidification has been limited by the high costs of quality tools to perform ocean acidification treatments in the lab. The Open Acidification Tank Controller is designed to reduce the cost of ocean acidification research by providing a device that can monitor and control pH and temperature of aquaria as well as or better than commercially available research-grade devices, but for less than $250 USD per aquarium. The device is centered around an Arduino Mega 2560 and is assembled into a 3D printed housing. It monitors pH using a BNC glass pH probe and temperature using a three-wire waterproof PT100 temperature sensor. The Open Acidification Tank Controller also features web-based parameter reporting, and data storage to a micro-SD card. This device can hold aquarium pH and temperature at given setpoints, ramp between two values over a user-defined time period, or produce a sine-wave fluctuation in values.

The Open-source Camera Trap for Organism Presence and Underwater Surveillance (OCTOPUS).

This Open-source Camera Trap for Organism Presence and Underwater Surveillance (OCTOPUS) was designed to operate as a motion activated camera trap, deployable at depths of up to 800 ft for ∼72 h deployments. The core components of the OCTOPUS are built off a Raspberry Pi 3B+ with a custom PCB hat which operates a strobe lighting system and a high definition Arducam camera. When an appropriate threshold of motion is detected, the OCTOPUS captures a high-definition image of the subject. Field trials for this system demonstrated its use for cryptic benthic organisms, specifically small octopus (Octopus rubescens). The OCTOPUS collected data on several species allowing the observation and quantification of interspecific and conspecific interactions. This system unlocks the potential of autonomous underwater data collection for a wide range of applications, from species specific observations to large scale ecological assessments.

Open Source Solutions in Experimental Design: An Introduction to the Symposium.

The Open Science movement has increased dramatically in popularity with deserved calls to action around transparency, access to resources, and inclusion in our field. However, its practical applications within experimental design have been slow to uptake, with researchers unsure where to even start with the dizzying array of open source hardware and software solutions available. The perceived time investment and unknown cost, especially in implementing open source hardware, has stagnated the implementation of inexpensive experimental solutions, but we sought to increase awareness to lower the barrier to participation in this space. While there are countless technical and financial advantages to integrating open source solutions into every biologist's experimental design, we put an emphasis on the "people" part of the equation in our symposium. This symposium championed innovative experimental designs by early career Society for Integrative and Comparative Biology researchers across all fields of biology, from plants to animals, in the lab or in the field, or even virtually engaging with the public and students. The Open Science movement operates within community norms that champion transparency, continuous development, and collaboration. These values are congruent with the priorities of reducing barriers to participation in science, and we hope our symposium's collection of open source solutions encourages readers to adopt these or other innovative designs into their own experimentation.

Den-Associated Behavior of Octopus rubescens Revealed by a Motion-Activated Camera Trap System.

Dens are a crucial component of the life history of most shallow water octopuses. However, den usage dynamics have only been explored in a few species over relatively short durations, and Octopus rubescens denning behavior has never been explored in situ. We built four underwater camera traps to observe the behavior of O. rubescens in and around their dens. To distinguish individuals, octopuses were captured and given a unique identifiable visible implant elastomer tag on the dorsal side of their mantle. After being tagged and photographed, each octopus was released back to its original capture site within its original den bottle. The site is unique in that octopuses reside almost exclusively in discarded bottles, therefore aiding in locating and monitoring dens. Motion-activated cameras were suspended in a metal field-of-view above bottle dens of released octopuses to observe den-associated behaviors. Cameras were regularly retrieved and replaced to allow continuous monitoring of den locations in 71 h intervals for over a month. We found that O. rubescenswas primarily active during the day and had frequent interactions with conspecifics (other members within the species). We also found that rockfish and red rock crabs tended to frequent den locations more often when octopuses were not present, while kelp greenling both visited dens more frequently and stayed longer when octopuses were present. Our results, demonstrate the utility of motion-activated camera traps for behavioral and ecological studies of nearshore mobile organisms.

Providing interactive and field laboratories while teaching university marine biology classes in an era of COVID-19.

An entirely online upper-division university marine invertebrates course modeled after a field experience-intensive course that also provided interaction with live animals and research experience was offered at Rosario Beach Marine Laboratory in the summer of 2020. We describe online methods we used for providing field experiences to students participating online, as well as a workstation and interactive method for identification and detailed anatomical examination of live macroinvertebrates with students. Students were also involved as active participants in a field research project. Nearly all of the equipment involved is inexpensive or readily available in most university biology laboratories or classrooms.

Impact of Short- and Long-Term Exposure to Elevated Seawater Pco2 on Metabolic Rate and Hypoxia Tolerance in Octopus rubescens.

AbstractMuch of the CO2 released by human activity into the atmosphere is dissolving into the oceans, making them more acidic. In this study we provide the first data on the short- and long-term impacts of ocean acidification on octopuses. We measured routine metabolic rate (RMR) of Octopus rubescens at elevated CO2 pressure (Pco2) with no prior acclimation and 1 or 5 wk of acclimation and critical oxygen pressure (Pcrit) after 5 wk of acclimation. Our results show that with no prior acclimation, octopuses had significantly higher RMRs in 1,500-µatm Pco2 environments than octopuses in 700- or 360-µatm environments. However, after both 1 and 5 wk of acclimation there was no significant difference in RMRs between octopuses at differing Pco2, indicating that octopuses acclimated rapidly to elevated Pco2. In octopuses acclimated for 5 wk at 1,500 µatm Pco2, we observed impaired hypoxia tolerance, as demonstrated by a significantly higher Pcrit than those acclimated to 700 µatm Pco2. Our findings suggest that O. rubescens experiences short-term stress in elevated Pco2 but is able to acclimate over time. However, while this species may be able to acclimate to near-term ocean acidification, compounding environmental effects of acidification and hypoxia may present a physiological challenge for this species.