Phylum Chordata

Phylum Chordata

The phylum Chordata contains all animals that possess, at some point during their lives, a hollow nerve cord and a notochord, a flexible rod between the nerve cord and the digestive track. The phylum Chordata is an extremely diverse phylum, and the one most recognizable to us. The phylum contains about 43,700 species, most of them concentrated in the subphylum Vertebrata, making it the third-largest phylum in the animal kingdom. The phylum Chordata is divided into three subphylums: Urochordata (tunicates), Cephalachordata (lancelets), and Vertebrata (vertebrates). The first two phyla are very small containing only about 2,000 species total. Tunicates are marine animals that only show the attributes of the chordata phylum in the larva stage, and when they turn into adults lose the notochord and nerve cord. Adult tunicates look like small sacs around 3 cm tall attached to the ocean floor. Lancelets, which are similar in appearance to small fish, keep the nerve chord and notochord into maturity but are extremely simple in structure and lack a backbone.

The third phylum, vertebrata, is the most important, and is distinguished by a backbone (made either of bone or cartilage) containing interlocking vertebrae and a skull enclosing a brain.

Features:  The most distinctive morphological features of chordates are the notochord, nerve cord, and visceral clefts and arches.

The notochord is an elongate, rod-like, skeletal structure dorsal to the gut tube and ventral to the nerve cord.The nerve cord of chordates develops dorsally in the body as a hollow tube above the notochord. The visceral (also called pharyngeal or gill) clefts and arches are located in the pharyngeal part of the digestive tract behind the oral cavity and anterior to the esophagus. The visceral clefts appear as several pairs of pouches that push outward from the lateral walls of the pharynx eventually to reach the surface to form the clefts. 

http://faculty.college-prep.org/~bernie/sciproject/project/Kingdoms/Animal%20Kingdom%20-%205/Local%20copy/classification/chordata.html

http://tolweb.org/Chordata/2499

http://www.misterabrams.com/biosite/biopages/animals/animal_notes/chorda1.gif

Phylum Chordata: Subphylum UrochordataThe Urochordata, sometimes known as the Tunicata, are commonly known as "sea squirts." The

body of an adult tunicate is quite simple, being essentially a sack with two siphons through which water enters and exits. Water is filtered inside the sack-shaped body. However, many tunicates have a larva that is free-swimming and exhibits all chordate characteristics: it has a notochord, a .dorsal nerve cord, pharyngeal slits, and a post-anal tail. This "tadpole larva" will swim for some time; in many tunicates, it eventually attaches to a hard substrate, it loses its tail and ability to move, and its nervous system largely disintegrates. Some tunicates are entirely pelagic; known as salps, they typically have barrel-shaped bodies and may be extremely abundant in the open ocean.

Urochordates are small marine animals with larvae that swim freely and adults that attach themselves to the

ocean floor.

Characteristics of Urochordata:- 1)Possesses a Notochord,a hollow nerve cord and a post anal tail. 2)Body has more than two cell layers and includes tissues and organs. 3)Has a U shaped gut. 4)Body has no coelomic body cavity. 5)Body wholly enclosed in a 'tunic' of secreted protein and cellulose-like material. 

6)Are hermaphroditic, normally with only one ovary and testis. 7)Has a nervous system composed of a anterior ganglion from which individual nerves issue. 8)Has no excretory organs. 9)Has a distinct larval stage. 10)All are filter feeders. 11)Live in marine environments. 12)About 2,000 species currently known.

http://www.earthlife.net/inverts/urochordata.html

http://www.ucmp.berkeley.edu/chordata/urochordata.html

http://www.encyclopedia.com/topic/Urochordata.aspx

Tunicates. Photo by Crissy Huffard, UCMP

Spicule from a living tunicate from Moorea, French Polynesia, photographed using an Environmental Scanning Electron Microscope

https://www.mun.ca/biology/scarr/142007_Urochordata.jpg

Adult form Larvae form

Phylum Chordata: Subphylum CephalochordataThe Cephalochordata are a small subphylum (about 28 species) of of small, 5 to 10 centimetres long, but fascinating animals. visually they look like simplified fishes, and they are quite capable of swimming short distances. Normally however they prefer to spend their time in the sand of marine shores. All known species are marine. They occur all around the world in both temperate and tropical waters. They have long fascinated biologists because they exhibit all four basic characteristics of the phylum Chordata (a dorsal nerve cord, a notochord, a post annul tail and

pharyngeal gill slits) in the adult stage of their lives. Among the 28 known species one occurs off European shores (Branchiostoma lanceolatum) which was the original lancelet, and four occur of the coasts of North America, one of which isBranchiostoma virginiae.

Known as lancelets or as amphioxus (from the Greek for "both [ends] pointed," in reference to their shape), cephalochordates are small, eel-like, unprepossessing animals that spend much of their time buried in sand. However, because of their remarkable morphology, they have proved crucial in understanding the morphology and evolution of chordates in general -- including vertebrates.

Since cephalochordates have no hard parts, their fossil record is extremely sparse. However, fossil cephalochordates have been found in very old rocks indeed, predating the origin of the vertebrates. The famous Middle Cambrian Burgess Shale of British Columbia has yielded a few fossils of Pikaia, which appears to be a cephalochordate (although the fossils are still being restudied). More recently, Yunnanozoon, from the Early Cambrian of south China, was reported to be a cephalochordate, the earliest known (Chen et al., 1995). These fossils show that the chordate lineage appeared very early in the known history of the animal kingdom, and they strengthen the case for an origin of true vertebrates from a cephalochordate-like ancestor.

http://www.earthlife.net/inverts/cephalochordata.html

http://www.ucmp.berkeley.edu/chordata/cephalo.html

https://classconnection.s3.amazonaws.com/85/flashcards/726085/png/subphylum_cephalochordata__(lancelets)_11323460553942.png

https:// classconnection.s3.amazonaws.com/990/flashcards/1347990/jpg/lancelet_anatomy1334507409575.jpg

Cepahalochordata diagram

Phylum Chordata: Subphylum Vertebrata: Class MammaliaMammals are members of class Mammalia, air-breathingvertebrate animals characterized by the possession ofendothermy, hair, three middle ear bones, and mammary glands functional in mothers with young. Most mammals also possess sweat glands and specialized teeth. The largest group of mammals, the placentals, have a placenta which feeds the offspring during gestation. The mammalian brain, with its characteristic neocortex, regulates endothermic and circulatory systems, the latter featuring red blood cells lacking nuclei and afour-chambered heart. Mammals range in size from the 30–40 millimeter (1- to 1.5-inch) bumblebee bat to the 33-meter (108-foot) blue whale. 

Mammals are both the most diverse and the most advanced of all the groups in the kingdom Animalia, though they make up only about 4,600 species. Mammals are distributed worldwide, occurring on all continents and most islands. Even islands that are said to be without mammals will have whales in the nearby waters. One species has even begun to colonize local space off earth.

http://eol.org/pages/1642/overview

http://nellyshaven.weebly.com/class-mammalia.html

http://faculty.college-prep.org/~bernie/sciproject/project/Kingdoms/Animal%20Kingdom%20-%205/Local%20copy/classification/chordata.html

http://mammalsamphibiansreptilesbirds.wikispaces.com/file/view/collage_mammals.jpg/98252731/collage_mammals.jpg

Phylum Chordata: Subphylum Vertebrata: Class Mammalia: Subclass Monotremata

 The first group of mammals, called monotremes, lay eggs similar to those of birds. There are only five living monotreme species: the duck-billed platypus and four

species of echidna (also known as spiny anteaters). All of them are found only in Australia and New Guinea. Monotremes are not a very diverse group today, and

there has not been much fossil information known until rather recently.

http://www.ucmp.berkeley.edu/mammal/monotreme.html

Echidna. Photo by Dr. Lloyd Glenn Ingles © 2001 California Academy of Sciences.

Platypus brestfeeding its babies

http://i.imgur.com/eVIl8Um.jpghttps://qph.is.quoracdn.net/main-qimg-0873fc1c68360350767571a7d7d8eacf?convert_to_webp=true

Platypus eggs

Phylum Chordata: Subphylum Vertebrata: Class Mammalia: Subclass Marsupialia

Marsupials are the group of mammals commonly thought of as pouched mammals (like the wallaby and kangaroo at left). They give live birth, but they do not have long gestation times like placental mammals. Instead, they give birth very early and the young animal, essentially a helpless embryo, climbs from the mother's birth canal to the nipples. There 

it grabs on with its mouth and continues to develop, often for weeks or months depending on the species. The short gestation time is due to having a yolk-type placenta in the mother marsupial. Placental mammals nourish the developing embryo using the mother's blood supply, allowing longer gestation times.

They include kangaroos, koalas (above left), tasmanian devils, wombats (above right), and other typical Australian mammals. Until recently, they also included the marsupial wolf, Thylacinus (below). Like the quagga, the marsupial wolf is now extinct. The last individual was seen in Tasmania in the

1950s.

Thylacinus, an extinct marsupial wolf.

Red-necked Wallaby. Photo by Gerald and Buff Corsi, © 2002 California Academy of Sciences.

Red Kangaroo. Photo by Gerald and Buff Corsi, © 2002 California Academy of Sciences.

Marsupials

http://splarks.com/blog/wp-content/uploads/2012/09/MarsupialCollage1.jpg

(Fact lang siguro to)Phylum Chordata: Subphylum Vertebrata: Class Placodermi

Placodermi is a class of extinct armoured fish that known from fossils dating from the late Silurian to the end of the Devonian. As fierce as some Placoderms were, they persisted only 50 million years, which pales in comparison with the 400 million year history of sharks. Their head andthorax were covered by articulated armoured plates, while the rest of the body had no scales or small scales. 

Unlike all other jawed vertebrates, placoderms never had teeth, and did not descend from toothed ancestors. Instead, bony plates associated with the jaws performed the function of teeth, sometimes forming razor-like, literally self-sharpening edges.

http://webcache.googleusercontent.com/search?q=cache:http://www.fossilmuseum.net/Tree_of_Life/PhylumChordata/class_placodermi.htm

http://www.ucmp.berkeley.edu/vertebrates/basalfish/placodermi.html

Bothriolepis canadensis model sketch

http://www.ucmp.berkeley.edu/vertebrates/basalfish/dunkleosteus.jpg

http://www.fossilmuseum.net/Fossil_Galleries/Fish_Devonian/Dunkleosteous/Dunkleosteous1t.jpg

Dunkleosteus Armoured Fish Fossil ModelDevonianHamar L'ghdad, Morocco

links

http://www.infoplease.com/encyclopedia/science/chordata-subphylum-vertebrata.html

http://anthro.palomar.edu/animal/animal_4.htm

http://faculty.college-prep.org/~bernie/sciproject/project/Kingdoms/Animal%20Kingdom%20-%205/Local%20copy/classification/chordata.html