Cnidaria (silent c - pronounced // from New Latin cnida, fr. Gk κνιδη "nettle") is a phylum containing some 11000 species of relatively simple animals found exclusively in aquatic, mostly marine, environments. Cnidarians get their name from cnidocytes, which are specialized cells that carry stinging organelles. The corals, which are important reef-builders, belong here, as do the familiar sea anemones, jellyfish, sea pens, sea pansies and sea wasps. The names Coelenterata and Coelentera were formerly applied to the group, but as those names included the Ctenophores (comb jellies), they have been abandoned. Cnidarians are highly evident in the fossil records, having first appeared in the Precambrian era.

The basic body shape of a cnidarian consists of a sac with a gastrovascular cavity, with a single opening that functions as both mouth and anus. It has radial symmetry, meaning that whichever way it is cut along its central axis, the resulting halves would always be mirror images of each other. Their movement is coordinated by a decentralized nerve net and simple receptors. Several free-swimming Cubozoa and Scyphozoa possess rhopalia, complex sensory structures that can include image-forming eyes with lenses and retinas ^*, and a gravity-sensing statolith comparable in function to the otolith of the vertebrate inner ear. Tentacles surrounding the mouth contain nematocysts, specialized stinging cells, which they use to catch prey and defend themselves from predators. The ability to sting is what gives cnidarians their name.

There are four main classes of Cnidaria:

More on [ Cnidaria ]

PLoS Medicine: New Articles

Towards a Data Sharing Culture: Recommendations for Leadership from Academic Health Centers
Rebecca Crowley and colleagues propose that academic health centers can and should lead the transition towards a culture of biomedical data sharing.
Key Issues in Conducting a Meta-Analysis of Gene Expression Microarray Datasets
Adaikalavan Ramasamy and colleagues outline seven key issues and suggest a stepwise approach in conducting a meta-analysis of microarray datasets.
Revision Rates after Primary Hip and Knee Replacement in England between 2003 and 2006
Jan van der Meulen and colleagues show that about one in 75 patients with a primary hip or knee replacement needed a revision of their prosthesis within 3 years.

EurekAlert! - Biology

Biophysical Society names 2009 award recipients
Fri, 05 Sep 2008 00:00:00 -0400
(Biophysical Society) The Biophysical Society is pleased to announce the recipients of its 2009 Society awards. The eight recipients will receive their awards at the Society's 53rd Annual Meeting on Monday, March 2, 2009, at the Boston Convention and Exhibitions Center in Massachusetts.
Iowa State wins $18.5M grant to create NSF Center for Biorenewable Chemicals
Fri, 05 Sep 2008 00:00:00 -0400
(Iowa State University) The National Science Foundation has awarded Iowa State University and its research partners an $18.5 million grant to establish an NSF Engineering Research Center for Biorenewable Chemicals based at Iowa State. The center's focus will be to develop catalysts that promote the chemical reactions that can efficiently produce biorenewable chemicals. The center is also expected to create partnerships that promote innovation, transform engineered systems and produce engineering graduates who can contribute in a global economy.
INCF organizes the first congress dedicated to the emerging field of neuroinformatics
Fri, 05 Sep 2008 00:00:00 -0400
(INCF - International Neuroinformatics Coordinating Facility) The first INCF Congress of Neuroinformatics will convene Sept. 7-9 at the Stockholm City Conference Center in Stockholm. The emerging neuroinformatics field combines neuroscience and informatics research to develop advanced tools and approaches to understanding the structure and function of the brain. The tools may also be applied to brain disorders and diseases. With a broad international outreach, the meeting will bring together experts from all disciplines contributing to neuroinformatics.

Subscribe to Biology RSS feed