Semi-Supervised Visual Tracking of Marine Animals using Autonomous Underwater Vehicles

In-situ visual observations of marine organisms is crucial to developing behavioural understandings and their relations to their surrounding ecosystem. Typically, these observations are collected via divers, tags, and remotely-operated or human-piloted vehicles. Recently, however, autonomous underwater vehicles equipped with cameras and embedded computers with GPU capabilities are being developed for a variety of applications, and in particular, can be used to supplement these existing data collection mechanisms where human operation or tags are more difficult. Existing approaches have focused on using fully-supervised tracking methods, but labelled data for many underwater species are severely lacking. Semi-supervised trackers may offer alternative tracking solutions because they require less data than fully-supervised counterparts. However, because there are not existing realistic underwater tracking datasets, the performance of semi-supervised tracking algorithms in the marine domain is not well understood. To better evaluate their performance and utility, in this paper we provide (1) a novel dataset specific to marine animals located at http://warp.whoi.edu/vmat/, (2) an evaluation of state-of-the-art semi-supervised algorithms in the context of underwater animal tracking, and (3) an evaluation of real-world performance through demonstrations using a semi-supervised algorithm on-board an autonomous underwater vehicle to track marine animals in the wild.Comment: To appear in IJCV SI: Animal Trackin

Octopus arms exhibit exceptional flexibility

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Kennedy, E. B. L., Buresch, K. C., Boinapally, P., & Hanlon, R. T. Octopus arms exhibit exceptional flexibility. Scientific Reports, 10(1), (2020): 20872. doi:10.1038/s41598-020-77873-7.The octopus arm is often referred to as one of the most flexible limbs in nature, yet this assumption requires detailed inspection given that this has not been measured comprehensively for all portions of each arm. We investigated the diversity of arm deformations in Octopus bimaculoides with a frame-by-frame observational analysis of laboratory video footage in which animals were challenged with different tasks. Diverse movements in these hydrostatic arms are produced by some combination of four basic deformations: bending (orally, aborally; inward, outward), torsion (clockwise, counter-clockwise), elongation, and shortening. More than 16,500 arm deformations were observed in 120 min of video. Results showed that all eight arms were capable of all four types of deformation along their lengths and in all directions. Arms function primarily to bring the sucker-lined oral surface in contact with target surfaces. Bending was the most common deformation observed, although the proximal third of the arms performed relatively less bending and more shortening and elongation as compared with other arm regions. These findings demonstrate the exceptional flexibility of the octopus arm and provide a basis for investigating motor control of the entire arm, which may aid the future development of soft robotics.We gratefully acknowledge funding from Grant N00014-19-1-2445 from the Office of Naval Research, Tom McKenna and Marc Steinberg, Program Managers. We also thank the staff of the Marine Resources Center at MBL for assistance with water quality measurements, seawater system maintenance, and collection of food items for octopuses

The giant eyes of giant squid are indeed unexpectedly large, but not if used for spotting sperm whales

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in BMC Evolutionary Biology 13 (2013): 187, doi:10.1186/1471-2148-13-187.We recently reported (Curr Biol 22:683–688, 2012) that the eyes of giant and colossal squid can grow to three times the diameter of the eyes of any other animal, including large fishes and whales. As an explanation to this extreme absolute eye size, we developed a theory for visual performance in aquatic habitats, leading to the conclusion that the huge eyes of giant and colossal squid are uniquely suited for detection of sperm whales, which are important squid-predators in the depths where these squid live. A paper in this journal by Schmitz et al. (BMC Evol Biol 13:45, 2013) refutes our conclusions on the basis of two claims: (1) using allometric data they argue that the eyes of giant and colossal squid are not unexpectedly large for the size of the squid, and (2) a revision of the values used for modelling indicates that large eyes are not better for detection of approaching sperm whales than they are for any other task. We agree with Schmitz et al. that their revised values for intensity and abundance of planktonic bioluminescence may be more realistic, or at least more appropriately conservative, but argue that their conclusions are incorrect because they have not considered some of the main arguments put forward in our paper. We also present new modelling to demonstrate that our conclusions remain robust, even with the revised input values suggested by Schmitz et al

Potential for sound sensitivity in cephalopods

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Advances in Experimental Medicine and Biology 730 (2012): 125-128, doi:10.1007/978-1-4419-7311-5_28.Hearing is a primary sense in many marine animals and we now have a reasonable understanding of what stimuli generate clear responses, the frequency range of sensitivity, expected threshold values and mecha-nisms of sound detection for several species of marine mammals and fishes (Fay 1988; Au et al. 2000). For marine invertebrates, our knowledge of hearing capabilities is relatively poor and a definition or even certainty of sound detection is not agreed upon (Webster et al. 1992) despite their magnitude of biomass and often central role in ocean ecosystems. Cephalopods (squid, cuttlefish, octopods and nautilus) are particularly interesting subjects for inver-tebrate sound detection investigations for several reasons. Ecologically, they occupy many of the same niches as sound-sensitive fish (Budelmann 1994) and may benefit from sound perception and use for the same reasons, such as to detect predators, navigate, or locate conspecifics. Squid, for example, are often the prey of loud, echolocating marine mammals (Clarke 1996), and may therefore be expected to have evolved hearing to avoid predators. Anatomically, squid have complex statocysts that are considered to serve primarily as vestibular and acceleration detectors (Nixon and Young 2003). However, statocysts may also be analogs for fish otolithic organs, detecting acoustic stimuli (Budelmann 1992). Previous studies have debated the subject of squid hearing and recently there has been a revival of research on the subject. Here, we briefly review what is known about squid sound detection, revisit hearing definitions, discuss potential squid susceptibility to anthropogenic noise and suggest potential future research direc-tions to examine squid acoustic sensitivity.2013-01-2

Early multi-wavelength emission from Gamma-ray Bursts: from Gamma-ray to X-ray

The study of the early high-energy emission from both long and short Gamma-ray bursts has been revolutionized by the Swift mission. The rapid response of Swift shows that the non-thermal X-ray emission transitions smoothly from the prompt phase into a decaying phase whatever the details of the light curve. The decay is often categorized by a steep-to-shallow transition suggesting that the prompt emission and the afterglow are two distinct emission components. In those GRBs with an initially steeply-decaying X-ray light curve we are probably seeing off-axis emission due to termination of intense central engine activity. This phase is usually followed, within the first hour, by a shallow decay, giving the appearance of a late emission hump. The late emission hump can last for up to a day, and hence, although faint, is energetically very significant. The energy emitted during the late emission hump is very likely due to the forward shock being constantly refreshed by either late central engine activity or less relativistic material emitted during the prompt phase. In other GRBs the early X-ray emission decays gradually following the prompt emission with no evidence for early temporal breaks, and in these bursts the emission may be dominated by classical afterglow emission from the external shock as the relativistic jet is slowed by interaction with the surrounding circum-burst medium. At least half of the GRBs observed by Swift also show erratic X-ray flaring behaviour, usually within the first few hours. The properties of the X-ray flares suggest that they are due to central engine activity. Overall, the observed wide variety of early high-energy phenomena pose a major challenge to GRB models.Comment: Accepted for publication in the New Journal of Physics focus issue on Gamma Ray Burst

INTEGRAL upper limits on gamma-ray emission associated with the gravitational wave event GW150914

Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we put upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, discovered by the LIGO/Virgo collaboration. The omni-directional view of the INTEGRAL/SPI-ACS has allowed us to constrain the fraction of energy emitted in the hard X-ray electromagnetic component for the full high-probability sky region of LIGO trigger. Our upper limits on the hard X-ray fluence at the time of the event range from $F_{\gamma}=2 \times 10^{-8}$ erg cm$^{-2}$ to $F_{\gamma}=10^{-6}$ erg cm$^{-2}$ in the 75 keV - 2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy E$_\gamma/$E$_\mathrm{GW}<10^{-6}$. We discuss the implication of gamma-ray limits on the characteristics of the gravitational wave source, based on the available predictions for prompt electromagnetic emission.Comment: accepted for publication in ApJ

Rethinking professional practice: the logic of competition and the crisis of identity in housing practice

The relationship between professionalism, education and housing practice has become increasingly strained following the introduction of austerity measures and welfare reforms across a range of countries. Focusing on the development of UK housing practice, this article considers how notions of professionalism are being reshaped within the context of welfare retrenchment and how emerging tensions have both affected the identity of housing professionals and impacted on the delivery of training and education programmes. The article analyses the changing knowledge and skills valued in contemporary housing practice and considers how the sector has responded to the challenges of austerity. The central argument is that a dominant logic of competition has culminated in a crisis of identity for the sector. Although the focus of the article is on UK housing practice, the processes identified have a wider relevance for the analysis of housing and welfare delivery in developed economies