Sipuncula History The first species of this phylum was described in 1827 by the French zoologist Henri Marie Ducrotay de Blainville who named it Sipunculus vulgaris. A related species was later described as Golfingia macintoshii by E. Ray Lankester. The specimen was provided by a friend of his, Professor Mackintosh. The specimen was dissected by Lankester between rounds of golf at Saint Andrews golf club in Scotland from which the species derives its name. Habitat Sipunculids are all marine and are relatively common, and live in shallow waters, either in burrows or in discarded shells like hermit crabs do. Anatomy Sipunculans are worm-like animals ranging from 2 to 720 millimetres (0.079 to 28.346 in) in length, with most species being under 10 centimetres (3.9 in). Three genera (Aspidosiphon, Lithacrosiphon and Cloeosiphon) possess epidermal modifications, called the anal shield near the anteriorly located anus on the trunk just below the introvert of the animal. Edibility
Cuttlefish Cuttlefish eat small mollusks, crabs, shrimp, fish, octopuses, worms, and other cuttlefish. Their predators include dolphins, sharks, fish, seals, seabirds, and other cuttlefish. Their life expectancy is about one to two years. Recent studies indicate cuttlefish are among the most intelligent invertebrates. Cuttlefish also have one of the largest brain-to-body size ratios of all invertebrates. Video of a cuttlefish in its natural habitat Physiology Cuttlebone A cuttlefish possesses an internal structure called the cuttlebone, which is porous and is made of aragonite. This broadclub cuttlefish (Sepia latimanus) can go from camouflage tans and browns (top) to yellow with dark highlights (bottom) in less than a second. Skin An infant cuttlefish protects itself with camouflage The chromatophores are elastic sacs containing different pigments. Camouflage The color variations in the mimicked substrate and animal skin are very similar. Eyes Cuttlefish eye closeup
Cmdr_Hadfield : Tonight's Finale: Our Earth... Xenoturbella Xenoturbella is a genus of bilaterian animals; it contains two marine worm-like species. The first known species (Xenoturbella bocki) was discovered in 1915 by Sixten Bock but the first published description was only in 1949 by Einar Westblad. Taxonomy The genus Xenoturbella contains two species: Its taxonomic position has been considered enigmatic since its discovery. Description Life cycle The association of specimens of Xenoturbella with mollusc larva has led many to suggest that they are molluscivores. Eggs of Xenoturbella are 0.2 mm wide, pale orange and opaque. Newly hatched embryos are free-swimming (tending to stay close to water surface) and ciliated. References Jump up ^ Westblad, E (1949) Xenoturbella bocki n. g., n. sp., a peculiar, primitive Turbellarian type. Additional material E. External links
Turritopsis nutricula Turritopsis nutricula is a small jellyfish. Several different species of the genus Turritopsis were formerly classified as T. nutricula, including the "immortal jellyfish" which is now classified as T. dohrnii. References External links Media related to Turritopsis at Wikimedia Commons Data related to Turritopsis nutricula at Wikispecies Astronomy Picture of the Day Rotifer In some recent treatments, rotifers are placed with acanthocephalans in a larger clade called Syndermata. Taxonomy and naming About 2200 species of rotifers have been described. Their taxonomy is currently in a state of flux. One treatment places them in the phylum Rotifera, with three classes: Seisonidea, Bdelloidea and Monogononta. The largest group is the Monogononta, with about 1500 species, followed by the Bdelloidea, with about 350 species. There are only two known genera with three species of Seisonidea. The Acanthocephala, previously considered to be a separate phylum, have been demonstrated to be modified rotifers. The Rotifera, strictly speaking, are confined to the Bdelloidea and the Monogonata. Etymology The word "rotifer" is derived from a Latin word meaning "wheel-bearer", due to the corona around the mouth that in concerted sequential motion resembles a wheel (though the organ does not actually rotate). Anatomy Digestive system Biology
Alpheidae The family is diverse and worldwide in distribution, consisting of about 600 species within 38 or more genera. The two most prominent genera are Alpheus and Synalpheus, with species numbering well over 250 and 100, respectively. Most snapping shrimp dig burrows and are common inhabitants of coral reefs, submerged seagrass flats and oyster reefs. While most genera and species are found in tropical and temperate coastal and marine waters, Betaeus inhabits cold seas and Potamalpheops is found only in freshwater caves. When in colonies, the snapping shrimp can interfere with sonar and underwater communication. The shrimp are a major source of noise in the ocean. Description Ecology Some pistol shrimp species share burrows with goby fishes in a symbiotic relationship. Social behavior has been discovered in the genus Synalpheus. Pistol shrimp have also been noted for their ability to reverse claws. Snapping effect General References
Astrophysics: Fire in the hole! Andy Potts In March 2012, Joseph Polchinski began to contemplate suicide — at least in mathematical form. A string theorist at the Kavli Institute for Theoretical Physics in Santa Barbara, California, Polchinski was pondering what would happen to an astronaut who dived into a black hole. Obviously, he would die. But how? According to the then-accepted account, he wouldn’t feel anything special at first, even when his fall took him through the black hole’s event horizon: the invisible boundary beyond which nothing can escape. But Polchinski’s calculations, carried out with two of his students — Ahmed Almheiri and James Sully — and fellow string theorist Donald Marolf at the University of California, Santa Barbara (UCSB), were telling a different story1. Free interview Zeeya Merali talks about what would happen if she fell into a black hole The team’s verdict, published in July 2012, shocked the physics community. Fiery origins Quantum mechanics says that information cannot be destroyed.
Dicyemida Dicyemida, or Rhombozoa, is a phylum of tiny parasites that live in the renal appendages of cephalopods. Although the name "Dicyemida" precedes "Rhombozoa" in usage, and is preferred by most contemporary authors, "Rhombozoa" still enjoys much popular support. Taxonomy Classification is controversial. Traditionally, dicyemids have been grouped with the Orthonectida in the Mesozoa; however, molecular phylogenies indicate that dicyemids may be more closely related to the roundworms. The phylum is not divided in classes, but contains three families, Conocyemidae, Dicyemidae, and Kantharellidae. Molecular evidence suggests that this phylum are derived from the Lophotrochozoa. Anatomy Life cycle Dicyemids exist in both asexual and sexual forms. As the infection ages, perhaps as the nematogens reach a certain density, vermiform larvae mature to form rhombogens, the sexual life stage, rather than more nematogens. References Furuya H, Tsuneki K (May 2003).
Mantis shrimp Called "sea locusts" by ancient Assyrians, "prawn killers" in Australia and now sometimes referred to as "thumb splitters" – because of the animal's ability to inflict painful gashes if handled incautiously – mantis shrimp sport powerful claws that they use to attack and kill prey by spearing, stunning, or dismemberment. Although it only happens rarely, some larger species of mantis shrimp are capable of breaking through aquarium glass with a single strike from this weapon. Ecology These aggressive and typically solitary sea creatures spend most of their time hiding in rock formations or burrowing intricate passageways in the sea bed. Classification and the claw Mantis shrimp from the front Around 400 species of mantis shrimp have currently been described worldwide; all living species are in the suborder Unipeltata. They are commonly separated into two distinct groups determined by the manner of claws they possess: Eyes Suggested advantages of visual system