Stalked Crinoid Locomotion, and its Ecological and Evolutionary Implications

In the past two decades, much direct evidence has been gathered on active crawling by stalked crinoids, a group generally thought to be sessile. Detailed descriptions of crawling mechanics of isocrinids in aquaria revealed only exceedingly slow movements (~0.1 mm sec-1). Crawling at such speeds severely restricted the range of roles that this behavior could play in stalked crinoid biology and, consequently, in its potential impact on their ecology and evolutionary history. Here, we provide evidence collected in situ by submersible near Grand Bahama Island at a depth of 420 m for a different mode of crawling in stalked crinoids. Its most striking feature is a speed two orders of magnitude greater (~10-30 mm sec-1) than previously observed. The biomechanical cause for the differences in speeds between the two crawling modes is related to the difference in the number of articulations, and thus length of the arm, involved in the power stroke. We suggest that the high speed mode may represent an escape strategy from benthic enemies such as cidaroid echinoids, which occur with stalked crinoids and have been shown to ingest them. A first-order tally of crinoid genera possessing morphological traits required for crawling is provided. Crawling may have characterized some Paleozoic taxa, such as some of the advanced cladids (a group very closely related to post-Paleozoic crinoids), but the Permo-Triassic extinction represents a major threshold between the largely sessile crinoid faunas of the Paleozoic and the increasingly dominant motile crinoids of the post-Paleozoic

Urchins in the Meadow: Paleobiological and Evolutionary Implications of Cidaroid Predation on Crinoids

Deep-sea submersible observations made in the Bahamas revealed interactions between the stalked crinoid Endoxocrinus parrae and the cidaroid sea urchin Calocidaris micans. The in situ observations include occurrence of cidaroids within “meadows” of sea lilies, close proximity of cidaroids to several upended isocrinids, a cidaroid perched over the distal end of the stalk of an upended isocrinid, and disarticulated crinoid cirri and columnals directly underneath a specimen of C. micans. Guts of two C. micans collected from the crinoid meadow contain up to 70% crinoid material. Two of three large museum specimens of another cidaroid species, Histocidaris nuttingi, contain 14–99% crinoid material. A comparison of cidaroid gut contents with local sediment revealed significant differences: sediment-derived material consists of single crinoid ossicles often abraded and lacking soft tissue, whereas crinoid columnals, cirrals, brachials, and pinnulars found in the cidaroids are often articulated, linked by soft tissue, and unabraded. Furthermore, articulated, multi-element fragments often show a mode of fracture characteristic of fresh crinoid material. Taken together, these data suggest that cidaroids prey on live isocrinids. We argue that isocrinid stalk-shedding, whose purpose has remained a puzzle, and the recently documented rapid crawling of isocrinids are used in escaping benthic predators: isocrinids sacrifice and shed the distal stalk portion when attacked by cidaroids and crawl away, reducing the chance of a subsequent encounter. If such predation occurred throughout the Mesozoic and Cenozoic (possibly since the mid-Paleozoic), several evolutionary trends among crinoids might represent strategies to escape predation by slow-moving benthic predators

Siting Study for a Hydrokinetic Energy Project Located Offshore Southeastern Florida: Protocols for Survey Methodology for Offshore Marine Hydrokinetic Energy Projects

Dehlsen Associates, LLC was awarded a grant by the United States Department of Energy (DOE) Golden Field Office for a project titled “Siting Study Framework and Survey Methodology for Marine and Hydrokinetic Energy Project in Offshore Southeast Florida,” corresponding to DOE Grant Award Number DE-EE0002655 resulting from DOE funding Opportunity Announcement Number DE-FOA- 0000069 for Topic Area 2, and it is referred to herein as “the project.” The purpose of the project was to enhance the certainty of the survey requirements and regulatory review processes for the purpose of reducing the time, efforts, and costs associated with initial siting efforts of marine and hydrokinetic energy conversion facilities that may be proposed in the Atlantic Ocean offshore Southeast Florida. To secure early input from agencies, protocols were developed for collecting baseline geophysical information and benthic habitat data that can be used by project developers and regulators to make decisions early in the process of determining project location (i.e., the siting process) that avoid or minimize adverse impacts to sensitive marine benthic habitat. It is presumed that such an approach will help facilitate the licensing process for hydrokinetic and other ocean renewable energy projects within the study area and will assist in clarifying the baseline environmental data requirements described in the U.S. Department of the Interior Bureau of Ocean Energy Management, Regulation and Enforcement (formerly Minerals Management Service) final regulations on offshore renewable energy (30 Code of Federal Regulations 285, published April 29, 2009). Because projects generally seek to avoid or minimize impacts to sensitive marine habitats, it was not the intent of this project to investigate areas that did not appear suitable for the siting of ocean renewable energy projects. Rather, a two-tiered approach was designed with the first step consisting of gaining overall insight about seabed conditions offshore southeastern Florida by conducting a geophysical survey of pre-selected areas with subsequent post-processing and expert data interpretation by geophysicists and experienced marine biologists knowledgeable about the general project area. The second step sought to validate the benthic habitat types interpreted from the geophysical data by conducting benthic video and photographic field surveys of selected habitat types. The goal of this step was to determine the degree of correlation between the habitat types interpreted from the geophysical data and what actually exists on the seafloor based on the benthic video survey logs. This step included spot-checking selected habitat types rather than comprehensive evaluation of the entire area covered by the geophysical survey. It is important to note that non-invasive survey methods were used as part of this study and no devices of any kind were either temporarily or permanently attached to the seabed as part of the work conducted under this project

Using Skeletons for Void Filling in Large-Scale Additive Manufacturing

In additive manufacturing (AM), slicing software is used to generate tool paths that are then converted to G-Code, which tells the 3D printer how to build a part. Toolpaths are generated using closed-loop paths. Sometimes the space left for a closed-loop is not sized perfectly. This can lead to overfill or underfill issues. Therefore, skeletonization of a polygon seeks to resolve this issue by creating an open-loop path to fill the voids between adjacent toolpaths. A straight skeleton was used to explore this work. Straight skeletonization represents the topological skeleton of a shape through line segments. After skeletonization, the extrusion rate can be varied to adjust bead width more precisely to fill the gap.Mechanical Engineerin

Cross-country collaboration for physical activity promotion: experiences from the European Union Physical Activity Focal Points Network

Background: An analysis of currently existing partnerships and cross-country collaboration for physical activity (PA) promotion is valuable for understanding how such partnerships operate, and how they impact national PA promotion efforts. This study aimed to outline the formation and development of the European Union's (EU) Physical Activity Focal Points Network, to evaluate its outputs and benefits and to describe its potential and challenges. Methods: A mixed methods approach were employed, including document analysis, semi-structured interviews with key officials and an online evaluation survey with the focal points. Results: The network was founded in 2014. Its main task is to coordinate the national collection of information for the EU's Health-Enhancing Physical Activity (HEPA) Monitoring Framework. Besides collecting data, focal points usually meet twice a year to share best practices and plan activities for the promotion of PA within the EU. The results of the evaluation survey show that participation in the network helped members specify goals for PA promotion, gain more knowledge regarding how to promote PA, identify more opportunities to promote PA in their country and to join a collaborative project with other countries. Conclusions: The study shows that the EU Physical Activity Focal Points Network may serve as an example of successful cross-country collaboration in PA promotion. The network has been able to make a contribution to monitoring the implementation of the EU Council Recommendation on HEPA across sectors in particular and of PA promotion in the EU in general. © 2022 The Author(s). Published by Oxford University Press on behalf of the European Public Health Association.This research was conducted as part of a project funded by the German Federal Ministry of Health (ZMVI1-2520WHO001 and ZMVI1-2521WHO001). The ministry was neither involved in writing this manuscript nor in the decision to submit the article for publication

The Shallow-Water Crinoid Fauna of Lakshadweep Atolls, North-Western Indian Ocean

A biodiversity survey carried out from 2016 to 2018 by the Department of Science and Technology in the Lakshadweep Atolls, India, recorded six species of shallow-water feather stars new to the archipelago (Comanthus wahlbergii, Comaster schlegelii, Himerometra robustipinna, Dichrometra palmata, Stephanometra indica, and Phanogenia typica). Himerometra sol A.H. Clark, 1912, previously known only from the Maldive Islands, is synonymized under Himerometra robustipinna (Carpenter, 1881). This study brings the total number of shallow-water crinoids recorded from Lakshadweep to ten species. Of the four species collected previously from the archipelago, only Comatella nigra was found in this survey. Of those not collected, Comatella stelligera and Oligometra serripinna are widespread in the Indo-western Pacific region, whereas Heterometra compta is known only from Lakshadweep, and its validity remains uncertain. The known shallow-water crinoid fauna of the archipelago is substantially less diverse than that of the adjacent and environmentally similar Maldive Islands, emphasizing the need for additional research in this island group, in particular, to determine whether the differences are actual or not, and whether they are based on natural conditions versus anthropogenic impacts

Taphonomy of Isocrinid Stalks: Influence of Decay and Autotomy

Stalks of isocrinid crinoids are differentiated into cirri-bearing columnals (nodals) and columnals lacking cirri (internodals). This skeletal differentiation allowed us to test whether stalk fragmentation is random or whether it occurs preferentially at a specific articulation. Our analyses indicate that the patterns of fragmentation in multicolumnal segments of extant isocrinids collected by submersible, by dredging, and in sediment samples, as well as those found as fossils, are nonrandom. The preferred plane of fragmentation corresponds to the synostosis, the articulation between a nodal and the internodal distal to it. In isocrinids this articulation has a characteristic morphology and is the site of autotomy. Although stalk shedding by autotomy may contribute to the observed patterns, decay experiments on isocrinid stalks, both in situ and in the lab, suggest that post-mortem disarticulation also results in nonrandom fragmentation. Thus both processes, autotomy and post-mortem decay, contribute to the observed pattern of fragmentation. Underlying both processes is the organization of soft tissues at synostoses

Growth, Injury, and Population Dynamics in the Extant Cyrtocrinid Holopus mikihe (Crinoidea, Echinodermata) near Roatan, Honduras

The crinoid order Cyrtocrinida is known mainly from Mesozoic fossils; its few surviving members, all from bathyal environments, are among the most peculiar living crinoids. Cyrtocrinids attributed to Holopus mikihe Donovan and Pawson, 2008, have been observed in large numbers via submersible off the western coast of Roatán, Honduras, on vertical and overhanging walls at depths between 430 and 640 m. Observations in 2012, 2013, and 2014 have permitted the first estimates of population structure, growth, and regeneration. Two size modes were observed; the flat barnacle-like “juvenile” stage resembles confamilial and co-occurring Cyathidium pourtalesiAméziane, 1999, whereas the larger “adults” elevate the crown on a stumplike calyx. The 99th percentile growth rate was 0.19 cm yr–1, giving a minimum predicted age of 16 yrs for the largest specimen and 8.7 yrs for the median specimen; the median growth rate was 0.04 cm yr–1, corresponding to 72 and 39 yrs. However, the slower rate of growth in juvenile compared to adult specimens means that these ages are underestimates; actual median age may be closer to 50 yrs. Arm regeneration rate is estimated at 0.6 cm yr–1, and 9.8% of adult individuals were visibly injured, giving an interval of about 1.4 yrs between arm loss events. No recruitment or mortality was observed, and aggregations of evenly-sized individuals were prevalent, consistent with sporadic local recruitment and mortality

Continuous-time Latent Markov Factor Analysis for exploring measurement model changes across time

Drawing valid inferences about daily or long-term dynamics of psychological constructs (e.g., depression) requires the measurement model (indicating which constructs are measured by which items) to be invariant within persons over time. However, it might be affected by time- or situation-specific artifacts (e.g., response styles) or substantive changes in item interpretation. To efficiently evaluate longitudinal measurement invariance, and violations thereof, we proposed Latent Markov factor analysis (LMFA), which clusters observations based on their measurement model into separate states, indicating which measures are validly comparable. LMFA is, however, tailored to “discretetime” data, where measurement intervals are equal, which is often not the case in longitudinal data. In this paper, we extend LMFA to accommodate unequally spaced intervals. The so-called “continuous-time” (CT) approach considers the measurements as snapshots of continuously evolving processes. A simulation study compares CT-LMFA parameter estimation to its discrete-time counterpart and a depression data application shows the advantages of CT-LMFA