Characteristics of Chordata

Animals in the phylum Chordata re-publishing four key features: a notochord, a dorsal hole nerve cord, pharyngeal slits, and also a post-anal tail.

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Key Takeaways

Key PointsThese attributes are only present during embryonic advancement in some chordates.The notochord provides skeletal support, gives the phylum that name, and develops into the vertebral column in vertebrates.The dorsal hole nerve cord develops into the main nervous system: the brain and spine.Pharyngeal slits are openings in the pharynx that construct into gill arches in bony fish and also into the jaw and inner ear in terrestrial animals.The post-anal tail is a skeletal extension of the posterior finish of the body, being missing in humans and also apes, although current during embryonic development.Key Termsnotochord: a functional rodlike framework that develops the main support that the human body in the shortest chordates; a primitive spinenerve cord: a dorsal tubular cord of nervous tissue over the notochord that a chordatepharyngeal slit: filter-feeding organs uncovered in non-vertebrate chordates (lancelets and also tunicates) and hemichordates living in aquatic environments

Characteristics the Chordata

Animals in the phylum Chordata re-publishing four an essential features that appear at part stage throughout their advancement (often, only during embryogenesis) (:

Defining attributes of chordates: In chordates, four usual features show up at some allude during development: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail.

a notochorda dorsal hollow nerve cordpharyngeal slitspost-anal tail


The chordates are named for the notochord: a flexible, rod-shaped framework that is discovered in the embryonic phase of all chordates and likewise in the adult stage of some chordate species. It is located between the digestive tube and the nerve cord, giving skeletal support through the length of the body. In part chordates, the notochord acts as the main axial support of the body throughout the animal’s lifetime.

In vertebrates, the notochord is present during embryonic development, in ~ which time the induces the development of the neural pipe which serves together a assistance for the occurring embryonic body. The notochord, however, is replaced by the vertebral obelisk (spine) in most adult vertebrates.

Dorsal hole Nerve Cord

The dorsal hollow nerve cord derives indigenous ectoderm the rolls right into a hole tube during development. In chordates, the is located dorsally (at the height of the animal) to the notochord. In comparison to the chordates, other animal phyla are defined by solid nerve cords that are located either ventrally or laterally. The nerve cord found in most chordate embryos establishes into the brain and spinal cord, which consist of the main nervous system.

Pharyngeal Slits

Pharyngeal slits room openings in the pharynx (the an ar just posterior to the mouth) that prolong to the exterior environment. In organisms the live in aquatic environments, pharyngeal slits allow for the leave of water that enters the mouth during feeding. Part invertebrate chordates usage the pharyngeal slits come filter food the end of the water the enters the mouth. In vertebrate fishes, the pharyngeal slits construct into gill arches, the bony or cartilaginous gill supports.

In most terrestrial animals, consisting of mammals and birds, pharyngeal slits are current only during embryonic development. In these animals, the pharyngeal slits develop into the jaw and inner ear bones.

Post-anal Tail

The post-anal tail is a posterior elongation of the body, extending beyond the anus. The tail contains skeletal elements and also muscles, which carry out a source of locomotion in aquatic species. In some terrestrial vertebrates, the tail likewise helps through balance, courting, and also signaling when danger is near. In humans and also other apes, the post-anal tail is existing during embryonic development, but is vestigial as an adult.

Chordates and also the evolution of Vertebrates

Chordata has two subphylums that invertebrates: Urochordata (tunicates) and Cephalochordata (lancelets).

Key Takeaways

Key PointsUrochordata (tunicates) and Cephalochordata (lancelets) space invertebrates due to the fact that they lack a backone.Larval tunicates (Urochordata) posses all four structures that classify chordates, but adult tunicates retain just pharyngeal slits.Larval tunicates swim because that a couple of days after hatching, then connect to a maritime surface and undergo metamorphosis right into the sessile adult form.Lancelets (Cephalochordata) are naval organisms the possess all functions of chordates; castle are named Cephalochordata due to the fact that the notochord extends right into the head.Lancelets might be the closest-living loved ones to vertebrates.Key TermsUrochordata: a taxonomic subphylum in ~ the phylum Chordata: the tunicates or sea squirtsCephalochordata: a taxonomic subphylum in ~ the phylum Chordata: the lanceletssessile: permanently attached to a substrate; not totally free to move about; “an attached oyster”

Chordates and also the advancement of Vertebrates

The most acquainted group the chordates is the vertebrates. However, in addition to the subphylum Vertebrata, the phylum Chordata additionally contains two subphylums the invertebrates: Urochordata and Cephalochordata. Members of these groups additionally possess the four distinctive features of chordates at some allude during your development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and also a post-anal tail. Uneven vertebrates, urochordates and cephalochordates never develop a bony backbone.


Members that Urochordata are likewise known together tunicates. The surname tunicate derives from the cellulose-like carbohydrate material, dubbed the tunic, i m sorry covers the external body of tunicates. Back tunicates are classified as chordates, just the larval kind possesses every four common structures. Adult only maintain pharyngeal slits and lack a notochord, a dorsal hole nerve cord, and a post-anal tail.

Urochordates: (a) This picture shows a swarm of the tunicate Botrylloides violaceus. (b) The larval phase of the tunicate possesses all of the features characteristic the chordates: a notochord, a dorsal hole nerve cord, pharyngeal slits, and also a post-anal tail. (c) In the adult stage, the notochord, nerve cord, and tail disappear.

Most tunicates space hermaphrodites. Tunicate larvae flower from eggs inside the adult tunicate’s body. After ~ hatching, a tunicate larva swims for a few days until it finds a an ideal surface on which it deserve to attach, usually in a dark or shaded location. It climate attaches via the head come the surface and undergoes metamorphosis right into the adult form, at which allude the notochord, nerve cord, and tail disappear.

Most tunicates live a sessile presence on the ocean floor and are suspension feeders. The primary foods of tunicates room plankton and also detritus. Seawater start the tunicate’s body v its incurrent siphon. Suspended product is filtered out of this water by a mucous network (pharyngeal slits) and also is passed right into the intestine via the action of cilia. The anus empties right into the excurrent siphon, which expulsion wastes and also water. Tunicates are found in shallow ocean waters approximately the world.


Members that Cephalochordata possess a notochord, dorsal hole nerve cord, pharyngeal slits, and also a post-anal tail in the adult stage. They execute not have actually a true brain, yet the notochord extends right into the head, which provides the subphylum its name ( “cephalo” is Greek because that head). Extinct members the this subphylum incorporate Pikaia, which is the oldest known cephalochordate. Pikaia fossils were recovered indigenous the burgess shales of Canada and dated to the middle of the Cambrian age, making them more than 500 million years old.

Extant members of Cephalochordata space the lancelets, named for their blade-like shape. Lancelets are just a few centimeters long and also are normally found hidden in sand at the bottom of warm temperate and also tropical seas. Choose tunicates, they space suspension feeders. V notochord and also paired muscle blocks, the lancelet and Pikaia might belong to the chordate group of pets from which the vertebrates have actually descended.

Cephalochrodates: The lancelet, favor all cephalochordates, has a head. Adult lancelets maintain the four an essential features the chordates: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail. Water native the mouth beginning the pharyngeal slits, i beg your pardon filter out food particles. The filtered water then collects in the atrium and also exits through the atriopore.

Key Takeaways

Key PointsThe clade Craniata includes animals that have a cranium: a bony, cartilaginous, or fibrous framework that surrounds the brain, jaw, and also facial bones.Members that Craniata encompass the vertebrates and hagfish.Genomic evidence argues that vertebrates diverged from cephalochordates (lancelets), which had actually previously sail from urochordates (tunicates).Fossil evidence says that most vertebrate diversity originated in the Cambrian explosion 540 million years ago.Two whole- genome duplications developed in beforehand vertebrate history.Key Termscranium: the component of the skull enclosing the brain, the braincasegenomics: the research of the complete genome of an organismCambrian explosion: the fairly rapid figure (over a period of many millions that years), roughly 530 million year ago, the most significant animal phyla as demonstrated in the fossil record

Craniata and Vertebrata

The clade Craniata is a subdivision of Chordata. Members of Craniata posses a cranium, i beg your pardon is a bony, cartilaginous, or fibrous structure bordering the brain, jaw, and also facial bones. The clade Craniata includes all vertebrates and the hagfishes (Myxini), which have a cranium but lack a backbone. Hagfish space the only known living pets that have a skull, yet not a vertebral column.


Hagfish: Although the lacks a backbone, the hagfish is a member the the Craniata clade due to the fact that it own a bony skull.

Clade Craniata: Craniata, including this fish (Dunkleosteus), are identified by the presence of a cranium, mandible, and also other face bones.

Vertebrates: Vertebrata are defined by the visibility of a backbone, such as the one the runs with the middle of this fish. All vertebrates are in the Craniata clade and have a cranium.

Vertebrate Evolution

In the phylum Chordata, the closest relatives of the vertebrates space the invertebrate chordates. Based on the molecular analysis of vertebrate and also invertebrate genomes (genomics), scientists can determine the evolutionary background of different phylogenetic groups.

According to these genomic analyses, vertebrates appear to be an ext closely concerned the lancelets (cephalochordates) than to the tunicates (urochordates). This argues that the cephalochordates an initial diverged from urochordates, and that vertebrates subsequently diverged indigenous the cephalochordates. This hypothesis is additional supported by the fossil of a 530 million-year-old organism v a mind and eyes like a vertebrate, however without the skull found in a craniate. A compare of the genomes of a lancelet, tunicate, lamprey, fish, chicken, and human evidenced that 2 whole-genome duplications emerged in the early history of the Vertebrata subphylum.

Both fossil and also genomic evidence suggests that vertebrates arose during the Cambrian explosion.The Cambrian explosion to be the relatively brief expectations of time during the Cambrian period during i beg your pardon many animal groups appeared and also rapidly diversified. Most modern animal phyla originated during the Cambrian explosion.

Characteristics that Vertebrates

Vertebrata is a subphlyum of Chordata the is further defined by their bony backbone.

Key Takeaways

Key PointsAs chordates, vertebrates have the same common features: a notochord, a dorsal hole nerve cord, pharyngeal slits, and also a post-anal tail.Vertebrates room further identified from chordates by their vertebral column, which forms when your notochord develops into the shaft of bony vertebrae be separated by discs.Vertebrates room the only chordates that have actually a brain as part of their main nervous system.Key Termsvertebral column: the collection of vertebrae that defend the spinal cord; the spinal columnchordate: a member of the phylum Chordata; numerous pets having a notochord at some stage of your development; in vertebrates this creates into the spinenotochord: a versatile rodlike structure that creates the main support of the body in the shortest chordates; a primitive spine

Characteristics of Vertebrates

Vertebrates space members the the subphylum Vertebrata, under the phylum Chordata and also under the kingdom Animalia. Animals that own bilateral symmetry have the right to be split into 2 groups, protostomes and deuterostomes, based upon their fads of embryonic development. The deuterostomes, who name converts as “second mouth,” consist of of two phyla: Chordata and also Echinodermata. Echinoderms are invertebrate marine pets that have pentaradial symmetry and a spiny body covering; the phylum has sea stars, sea urchins, and sea cucumbers. The phylum Chordata has two groups of invertebrate chordates, however the many conspicuous and also familiar members that Chordata are the vertebrates.

Phylum chordata: every chordates space deuterostomes, own a notochord. Vertebrates are identified by having a vertebral column.

As chordates, every vertebrates have actually a comparable anatomy and morphology v the exact same qualifying characteristics: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail. However, the subphylum Vertebrata is differentiated from the phylum Chordata through the advancement of the notochord into a bony backbone. Vertebrates incorporate the amphibians, reptiles, mammals, and birds, as well as the jawless fishes, bony fishes, sharks, and also rays.

Diversity that vertebrates: pets with backbones: The subphylum Vertebrata consists of all animals that own backbones, gills, and a central nervous device in at least one step of development. Vertebrates include amphibians, reptiles, mammals, and also birds, and the jawless fishes, bony fishes, sharks, and also rays.

More than 64,000 varieties of vertebrates have been described, yet the extant vertebrate types represent only a small part of all the vertebrates that have actually existed. Vertebrates selection in size from the frog varieties Paedophryne amauensis (as little as 7.7 mm (0.3 inch)) to the blue whale (as huge as 33 m (110 ft)). Vertebrates comprise around 4 percent of all described pet species; the remainder are invertebrates, which lack backbones.

Anatomy and also Morphology

All vertebrates are developed along the basic chordate human body plan: a stubborn rod running through the size of the pet (vertebral column), v a hollow tube that nervous organization (the spinal cord) over it and the gastrointestinal tract below. In every vertebrates, there is a mouth at anterior end of the animal and also an anus before the posterior end of the body. Over there is a tail posterior to the anus during at the very least one step of the animal’s development.

The Vertebral Column

Vertebrates are identified by the visibility of the vertebral column. In vertebrates, the notochord creates into the vertebral column or spine: a collection of bony vertebrae every separated through mobile discs. This vertebrae are always found ~ above the dorsal side of the animal. However, a couple of vertebrates have secondarily shed their vertebrae and, instead, retain the notochord right into adulthood (e.g., the sturgeon fish).


Vertebral column: A fossilized skeleton the the dinosaur Diplodocus carnegii shows severe example of the backbone that characterizes vertebrates.

Central concerned System

Vertebrates are additionally the only members of Chordata to own a brain. In chordates, the central nervous mechanism is based on a hollow nerve tube that runs dorsal to the notochord along the length of the animal. In vertebrates, the anterior end of the nerve pipe expands and differentiates into three brain vesicles.

Vertebrate Classification

Vertebrates are the largest group of chordates, with an ext than 62,000 living species. Vertebrates room grouped based upon anatomical and also physiological traits. The timeless groups incorporate Agnatha, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia.

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Animals the possess jaws are well-known as gnathostomes, an interpretation “jawed mouth.” Gnathostomes include fishes and also tetrapods (amphibians, reptiles, birds, and also mammals). Tetrapods have the right to be further split into two groups: amphibians and amniotes. Amniotes are pets whose eggs are adjusted for terrestrial living; this group contains mammals, reptiles, and also birds. Amniotic embryos, emerging in either an externally-shelled egg or one egg carried by the female, are detailed with a water-retaining environment and are safeguarded by amniotic membranes.