How to tag a jellyfish? A methodological review and guidelines to successful jellyfish tagging

Jellyfish have become a topic of interest of many marine scientists and managers alike due to their conspicuous socio-economic and environmental impacts. However, our knowledge about their "everyday life" remains limited. While electronic tags (transmitters and loggers) have been extensively used to study marine vertebrates for the past 50 years, tagging is still in its infancy for marine invertebrates and jellyfish in particular. Progress has been hampered by the difficulty and limited knowledge of attaching tags to soft-bodied animals. We argue that there is huge potential to use tagging to gather basic information on the ecology and behaviour of these species. Here, we give an overview of what has been learned so far by deploying tags on jellyfish, and why tagging is an appropriate method to study their behaviour and ecology. We then describe different tagging techniques, their advantages, disadvantages and challenges, and the steps to ensure future successful jellyfish tagging studies

The characteristics of woody debris and sediment distribution in headwater streams, southeastern Alaska

10.1139/cjfr-31-8-1386Canadian Journal of Forest Research3181386-1399CJFR

Mechanisms and behavioural functions of structural coloration in cephalopods

Octopus, squid and cuttlefish are renowned for rapid adaptive coloration that is used for a wide range of communication and camouflage. Structural coloration plays a key role in augmenting the skin patterning that is produced largely by neurally controlled pigmented chromatophore organs. While most iridescence and white scattering is produced by passive reflectance or diffusion, some iridophores in squid are actively controlled via a unique cholinergic, non-synaptic neural system. We review the recent anatomical and experimental evidence regarding the mechanisms of reflection and diffusion of light by the different cell types (iridophores and leucophores) of various cephalopod species. The structures that are responsible for the optical effects of some iridophores and leucophores have recently been shown to be proteins. Optical interactions with the overlying pigmented chromatophores are complex, and the recent measurements are presented and synthesized. Polarized light reflected from iridophores can be passed through the chromatophores, thus enabling the use of a discrete communication channel, because cephalopods are especially sensitive to polarized light. We illustrate how structural coloration contributes to the overall appearance of the cephalopods during intra- and interspecific behavioural interactions including camouflage