For more content, Click Here and experience this XYHor in its entirety! An arthropod ("joint-foot") is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages (paired appendages). Arthropods form the phylum Arthropoda, which includes Hexapoda (Insects; Springtails), Chelicerata (arachnids [Spiders, Scorpions]; Horseshoe Crabs, Sea Spiders) myriapods (Centipedes; Millipedes), and crustaceans (Crabs, Lobsters, Shrimp) and the extinct Trilobitomorpha (Trilobites). Arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Their versatility has enabled them to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80% of all described living animal species, some of which, unlike most animals, are very successful in dry environments. Arthropods' primary internal cavity is a hemocoel, which accommodates their internal organs, and through which their haemolymph â analogue of blood â circulates; they have open circulatory systems. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. Their nervous system is "ladder-like", with paired ventral nerve cords running through all segments and forming paired ganglia in each segment. The evolutionary ancestry of arthropods dates back to the Cambrian period. The group is generally regarded as monophyletic, and many analyses support the placement of arthropods with cycloneuralians (or their constituent clades) in a superphylum Ecdysozoa. Overall, however, the basal relationships of Metazoa are not yet well resolved. Likewise, the relationships between various arthropod groups are still actively debated.
The new discovery sheds light on the evolution of insect and crustacean nervous systems.
With help from 15 fossils recently discovered in Greenland, scientists are now able to peer inside the brain of an animal that lived 520 million years ago.
After their surprise resurgence into the Monterey Bay back in October, pelagic red crabs have returned! Also known as tuna crabs because of their natural affinity for being fast food for fast fish, these colorful crustaceans cruised into our Great Tide Pool this morning.
Pushed in by the high tide and the solid winter swell, Aquarium visitors and staff willing to brave the rain on a gray Monterey day were treated to a rare sight to sea. Indeed, before late last year, pelagic red crabs had not been seen in the bay since the massive El NiĂąo of 1983. Usually found off of Baja and southern California, these bio-indicators of warm water and shifted currents have once again found prime conditions to invadeâand be ingestedâoff our back deck.
A newly identified âspooky toxinâ launches a broad attack but might be eased with a version of a known drug.
Knocking out an animal 15 times your size â no problem. A newly identified toxin in the venom of a tropical centipede helps the insect overpower giant prey in about 30 seconds.
Hermaphrodites are common in the natural world, where animals may appear one sex but have the reproductive organs of both. But whatâs rare about these butterflies (and some crustaceans, birds) is that they are bilateral gynandromorphs, meaning they are both sexes split. Scientists think this happens when a femaleâs egg develops two nuclei, that become âdouble fertilizedâ in mating, resulting in an embryo thatâs half of each sex.Â
The top image is a colored Scanning Electron Micrograph (SEM) of three Acorn Barnacles attached to a rock. Barnacles are encrusters, attaching themselves permanently to a hard substrate. Around 1,220 barnacle species are currently known.
SEE HOW DIVERSE BARNACLES ARE
Acorn Barnacles, among the most common type, are sessile (non-motile), growing their shells directly onto the substrate. Once attached, these sedentary marine crustaceans filter plankton from the water using their feathery legs (not seen). These can be withdrawn into the hard shell when the barnacles are threatened or left out of water at low tide.Â
Barnacles attach themselves to rocks using a strong glue. The second SEM (above) shows a section through the byssus (glue threads) of an Acorn Barnacle. This adhesive has attracted much research, as it is hoped similar synthetic glues could be created for use in medicine and other environments that call for a glue that can be used underwater.
It has been recently discovered that before these clever little sea creatures attempt to attach themselves to their permanent perch, they release a small droplet of oil. This lipid substance displaces water and thus prepares the surface for their incredibly strong, phosphoprotein adhesive.
Technology could be used to wipe out malaria carrying mosquitos or other pests but UN experts say fears over possible military uses and unintended consequences strengthen case for a ban
Theyâre investing in Gene Drives.
(For a really good intro to gene drives and the opportunities and threats they pose: x) As the headline states, it can be used as an âextinction technologyâ. (It basically quickly forces genes to spread through a population.)
The article pretty much nails it when they point out that everyone is nervous about a branch of the military investing in this. Cause really, anyone looking into this should have the greatest amount of oversight possible. This technology can be used for a lot of good, but also a lot of bad. And most importantly, even the best intentions could have disastrous effects with this technology.
DARPA - the govâtâs fringe science division - basically argues that a big part of the rationale is to be ready for others who might use it in a negative way. Which does seem important, to be fair. I guess the question becomes, âwho watches the watchmen?â
Highlights:
A US military agency is investing $100m in genetic extinction technologies that could wipe out malarial mosquitoes, invasive rodents or other speciesâŚ
The use of genetic extinction technologies in bioweapons is the stuff of nightmares, but known research is focused entirely on pest control and eradicationâŚ
Some UN experts, though, worry about unintended consequences. One told the Guardian: âYou may be able to remove viruses or the entire mosquito population, but that may also have downstream ecological effects on species that depend on them.â
âMy main worry,â he added, âis that we do something irreversible to the environment, despite our good intentions, before we fully appreciate the way that this technology will work.ââŚ
âDarpa is not and should not be the only funder of gene-editing research but it is critical for the Department of Defense to defend its personnel and preserve military readiness,â he said.
Darpa believes that a steep fall in the costs of gene-editing toolkits has created a greater opportunity for hostile or rogue actors to experiment with the technology.
âThis convergence of low cost and high availability means that applications for gene editing â both positive and negative â could arise from people or states operating outside of the traditional scientific community and international norms,â the official said. âIt is incumbent on Darpa to perform this research and develop technologies that can protect against accidental and intentional misuse.â
P.s. Related story on how Britain wants to genetically alter rats to help reduce their overall numbers. (x)
@franzanth noticed this caterpillar (left) that looks like itâs mimicking weaver ants (right.) It turns out that the caterpillar is so good at mimicking ants that it even fools image recognition software.
Tiny peacock spiders make up for size in pizzazz. Males, like Maratus volans pictured here, are only about 5 mm long, but theyâre famous for their flashy midsection and leg-raising mating dance. To enchant a female, they display a flap-like body part called a fan. There are more than 40 peacock species including one, Maratus jactatus, that was nicknamed Sparklemuffin for its iridescent scales. Itâs a lot to impress a potential mate, but thereâs a lot at stake: if a female spider doesnât like your dance moves, she might just eat you alive.
Photo: JĂźrgen Otto
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