They are diurnal, hunting during the day, and are known to move, looping end over end, or contract, in response to light. New research published in BioMed Central's open access journal BMC Biology shows that stinging cells (cnidocytes) in hydra tentacles, which the animals use for self protection and to catch prey, are linked via a simple nervous system to primitive light responsive cells that co-ordinate the animals' feeding behavior.
This is the fresh water polyp, Hydra magnipapillata. Credit: Dr. David Plachetzki, University of California
Hydra are members of a family of radially symmetric animals (Cnidaria), all of which use specialized cnidocytes to catch prey. This family also includes well-known creatures such as jellyfish and corals, which, like other cnidarians, have the simple design of a mouth surrounded by tentacles. Hydra tentacles contain barbed, poison containing cnidocytes that they use to stun animals like the water flea, Daphnia, before eating them alive, and to protect themselves from attack by other animals.
Researchers from the University of California lead by Dr David Plachetzki have discovered that the light sensitive protein opsin found in sensory cells is able to regulate the firing of harpoon-like cnidocytes. These light sensitive neurons are found integrated into arsenals that include the stinging cnidocytes as well as desmoneme cnidocytes, used to grasp prey, and sticky isorhiza, which help the hydra to summersault at 10cm a day.
The linking of opsin to cnidocytes explains how hydra are able to respond to light even though they do not have eyes. Dr Plachetzki described how other proteins necessary for phototransduction are also present in the sensory cells. "Not only did we find opsin in the sensory neurons that connect to cnidocytes in the hydra, but we also found other components of phototransduction in these cells. These included cyclic nucleotide gated ion channels (CNG) required to transfer the signal and a hydra version of arrestin, which wipes the phototransduction slate clean for a second signal."
Dr Plachetzki continued, "We were also able to demonstrate that cnidocyte firing itself is effected by the light environment and that these effects are reversed when components of the phototransduction cascade are turned off."
Cnidarians have been around for over 600 million years. However the hydra's simple approach to using light, to aid survival and increase their chances of catching prey, uses the same visual pathway as humans and hints at a common ancestor.
Notes to Editors1. Cnidocyte discharge is regulated by light and opsin-mediated phototransduction
Article citation and URL available on request on the day of publication.
2. BMC Biology is the flagship biology journal of the BMC series, publishing open-access, peer-reviewed research and methodology articles of special importance and broad interest in any area of biology, as well as reviews, opinion pieces, comment and Q&As on topics of special or topical interest.
3. BioMed Central (http://www.biomedcentral.com/) is an STM (Science, Technology and Medicine) publisher which has pioneered the open access publishing model. All peer-reviewed research articles published by BioMed Central are made immediately and freely accessible online, and are licensed to allow redistribution and reuse. BioMed Central is part of Springer Science+Business Media, a leading global publisher in the STM sector.
Dr. Hilary Glover | EurekAlert!
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences