Characteristics of Chordata

Animals in the phylum Chordata re-superstructure four crucial features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

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Key Takeaways

Key PointsThese characteristics are only existing during embryonic breakthrough in some chordates.The notochord provides skeletal support, provides the phylum the name, and develops right into the vertebral pillar in vertebrates.The dorsal hole nerve cord creates into the central nervous system: the brain and spine.Pharyngeal slits space openings in the pharynx that construct into gill arcs in bony fish and also into the jaw and inner ear in terrestrial animals.The post-anal tail is a skeletal expansion of the posterior end of the body, being absent in humans and apes, although existing during embryonic development.Key Termsnotochord: a flexible rodlike framework that forms the main support that the body in the shortest chordates; a primitive spinenerve cord: a dorsal tubular cord of worried tissue over the notochord that a chordatepharyngeal slit: filter-feeding organs uncovered in non-vertebrate chordates (lancelets and tunicates) and also hemichordates living in aquatic environments

Characteristics the Chordata

Animals in the phylum Chordata re-publishing four vital features that show up at part stage throughout their development (often, only during embryogenesis) (:

Defining features of chordates: In chordates, four typical features appear at some suggest during development: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail.

a notochorda dorsal hole nerve cordpharyngeal slitspost-anal tail


The chordates are called for the notochord: a flexible, rod-shaped framework that is uncovered in the embryonic phase of all chordates and likewise in the adult phase of some chordate species. It is located in between the cradle tube and also the nerve cord, offering skeletal support through the size of the body. In some chordates, the notochord acts together the primary axial assistance of the body throughout the animal’s lifetime.

In vertebrates, the notochord is current during embryonic development, at which time that induces the advancement of the neural tube which serves together a support for the emerging embryonic body. The notochord, however, is replaced by the vertebral pillar (spine) in many adult vertebrates.

Dorsal hollow Nerve Cord

The dorsal hollow nerve cord derives from ectoderm that rolls into a hollow tube during development. In chordates, it is located dorsally (at the top of the animal) come the notochord. In contrast to the chordates, other pet phyla are characterized by hard nerve cords that are located either ventrally or laterally. The nerve cord discovered in many chordate embryos creates into the mind and spinal cord, which comprise the main nervous system.

Pharyngeal Slits

Pharyngeal slits space openings in the pharynx (the an ar just posterior come the mouth) that extend to the external environment. In organisms the live in aquatic environments, pharyngeal slits enable for the departure of water that enters the mouth during feeding. Some invertebrate chordates usage the pharyngeal slits come filter food the end of the water that enters the mouth. In vertebrate fishes, the pharyngeal slits develop into gill arches, the bony or cartilaginous gill supports.

In most terrestrial animals, including mammals and birds, pharyngeal slits are present only throughout embryonic development. In this animals, the pharyngeal slits construct into the jaw and inner ear bones.

Post-anal Tail

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

Chordates and the evolution of Vertebrates

Chordata contains two subphylums the invertebrates: Urochordata (tunicates) and also Cephalochordata (lancelets).

Key Takeaways

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

Chordates and the evolution of Vertebrates

The most familiar group of chordates is the vertebrates. However, in addition to the subphylum Vertebrata, the phylum Chordata also contains 2 subphylums the invertebrates: Urochordata and Cephalochordata. Members of these groups also possess the 4 distinctive features of chordates at some allude during their development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and also a post-anal tail. Uneven vertebrates, urochordates and also cephalochordates never develop a bony backbone.


Members the Urochordata are also known together tunicates. The surname tunicate derives indigenous the cellulose-like carbohydrate material, referred to as the tunic, i m sorry covers the external body of tunicates. Although tunicates room classified together chordates, just the larval kind possesses all four common structures. Adult only maintain pharyngeal slits and also lack a notochord, a dorsal hollow nerve cord, and a post-anal tail.

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

Most tunicates space hermaphrodites. Tunicate larvae flower from eggs within the adult tunicate’s body. After hatching, a tunicate larva swims because that a couple of days till it finds a an ideal surface on i m sorry it can attach, typically in a dark or shaded location. It then attaches via the head to the surface and undergoes metamorphosis right into the adult form, in ~ which allude the notochord, nerve cord, and tail disappear.

Most tunicates live a sessile presence on the ocean floor and also are suspension feeders. The primary foods items of tunicates room plankton and detritus. Seawater enters the tunicate’s body through its incurrent siphon. Suspended material is filtered the end of this water through a mucous network (pharyngeal slits) and also is passed into the intestine via the action of cilia. The anus empties right into the excurrent siphon, which expels wastes and water. Tunicates are discovered in shallow ocean waters roughly the world.


Members the Cephalochordata own a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail in the adult stage. They execute not have a true brain, however the notochord extends right into the head, which provides the subphylum its surname ( “cephalo” is Greek for head). Extinct members of this subphylum encompass Pikaia, i beg your pardon is the oldest known cephalochordate. Pikaia fossils to be recovered from the citizen shales of Canada and dated come the center of the Cambrian age, making them more than 500 million years old.

Extant members of Cephalochordata are the lancelets, named for your blade-like shape. Lancelets are only a couple of centimeters long and also are typically found buried in sand at the bottom of warm temperate and also tropical seas. Like tunicates, they are suspension feeders. V notochord and also paired muscle blocks, the lancelet and Pikaia might belong to the chordate group of pets from i m sorry the vertebrates have actually descended.

Cephalochrodates: The lancelet, favor all cephalochordates, has a head. Adult lancelets retain the four an essential features of chordates: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and also a post-anal tail. Water from the mouth beginning the pharyngeal slits, i m sorry filter the end food particles. The filtered water climate collects in the atrium and exits with the atriopore.

Key Takeaways

Key PointsThe clade Craniata includes pets that have actually a cranium: a bony, cartilaginous, or fibrous framework that surrounding the brain, jaw, and also facial bones.Members that Craniata include the vertebrates and also hagfish.Genomic evidence argues that vertebrates diverged from cephalochordates (lancelets), which had actually previously sail from urochordates (tunicates).Fossil evidence argues that most vertebrate diversity source in the Cambrian to explode 540 million year ago.Two whole- genome duplications developed in at an early stage vertebrate history.Key Termscranium: the part of the skull enclosing the brain, the braincasegenomics: the examine of the complete genome of an organismCambrian explosion: the relatively rapid illustration (over a duration of countless millions that years), around 530 million years ago, the most significant animal phyla as demonstrated in the fossil record

Craniata and Vertebrata

The clade Craniata is a subdivision the Chordata. Members the Craniata posses a cranium, which is a bony, cartilaginous, or fibrous structure bordering the brain, jaw, and also facial bones. The clade Craniata includes all vertebrates and also the hagfishes (Myxini), which have a cranium however lack a backbone. Hagfish room the only recognized living pets that have actually a skull, yet not a vertebral column.


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

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

Vertebrates: Vertebrata are defined by the presence of a backbone, such together the one that runs through the center of this fish. All vertebrates are in the Craniata clade and also have a cranium.

Vertebrate Evolution

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

According to this genomic analyses, vertebrates show up to be an ext closely related to the lancelets (cephalochordates) than to the tunicates (urochordates). This says that the cephalochordates an initial diverged from urochordates, and that vertebrates ultimately diverged indigenous the cephalochordates. This hypothesis is further supported by the fossil the a 530 million-year-old organism v a brain and eyes prefer a vertebrate, however without the skull uncovered in a craniate. A compare of the genomes of a lancelet, tunicate, lamprey, fish, chicken, and human confirmed that 2 whole-genome duplications occurred in the early history of the Vertebrata subphylum.

Both fossil and genomic evidence suggests that vertebrates developed during the Cambrian explosion.The Cambrian explosion to be the fairly brief span of time throughout the Cambrian duration during i beg your pardon many pet groups appeared and also rapidly diversified. Most modern animal phyla originated during the Cambrian explosion.

Characteristics of Vertebrates

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

Key Takeaways

Key PointsAs chordates, vertebrates have actually the same common features: a notochord, a dorsal hole nerve cord, pharyngeal slits, and also a post-anal tail.Vertebrates room further differentiated from chordates by your vertebral column, which develops when your notochord establishes into the pillar of bony vertebrae be separate by discs.Vertebrates room the only chordates that have actually a mind as component of their central nervous system.Key Termsvertebral column: the collection of vertebrae that protect the spinal cord; the spinal columnchordate: a member of the phylum Chordata; numerous pets having a notochord in ~ some phase of your development; in vertebrates this establishes into the spinenotochord: a functional rodlike framework that creates the key support of the human body in the lowest chordates; a primitive spine

Characteristics the Vertebrates

Vertebrates are members that the subphylum Vertebrata, under the phylum Chordata and under the kingdom Animalia. Animals that own bilateral symmetry deserve to be split into two groups, protostomes and deuterostomes, based on their trends of embryonic development. The deuterostomes, who name translates as “second mouth,” consists of two phyla: Chordata and also Echinodermata. Echinoderms space invertebrate marine animals that have actually pentaradial symmetry and also a spiny human body covering; the phylum includes sea stars, sea urchins, and sea cucumbers. The phylum Chordata contains two teams of invertebrate chordates, yet the many conspicuous and also familiar members of Chordata space the vertebrates.

Phylum chordata: all chordates space deuterostomes, possessing a notochord. Vertebrates are differentiated by having a vertebral column.

As chordates, all vertebrates have actually a comparable anatomy and morphology with the very same qualifying characteristics: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. However, the subphylum Vertebrata is identified from the phylum Chordata by the advance of the notochord right into a bony backbone. Vertebrates incorporate the amphibians, reptiles, mammals, and also birds, and the jawless fishes, bony fishes, sharks, and also rays.

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

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

Anatomy and Morphology

All vertebrates are built along the an easy chordate human body plan: a stubborn rod running through the size of the pet (vertebral column), with a hole tube of nervous tissue (the spinal cord) above it and also the gastrointestinal tract below. In every vertebrates, over there is a mouth in ~ anterior finish of the animal and also an anus prior to the posterior finish of the body. Over there is a tail posterior to the anus during at least one phase of the animal’s development.

The Vertebral Column

Vertebrates are defined by the visibility of the vertebral column. In vertebrates, the notochord develops into the vertebral tower or spine: a collection of bony vertebrae each separated by mobile discs. These vertebrae are constantly found on the dorsal next of the animal. However, a few vertebrates have actually secondarily shed their vertebrae and, instead, retain the notochord into adulthood (e.g., the sturgeon fish).


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

Central nervous System

Vertebrates are likewise the just members the Chordata to own a brain. In chordates, the central nervous device is based on a hollow nerve tube that runs dorsal come the notochord along the size of the animal. In vertebrates, the anterior finish of the nerve tube expands and differentiates into three mind vesicles.

Vertebrate Classification

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

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Animals the possess jaws are well-known as gnathostomes, definition “jawed mouth.” Gnathostomes incorporate fishes and tetrapods (amphibians, reptiles, birds, and also mammals). Tetrapods have the right to be further split into 2 groups: amphibians and also amniotes. Amniotes are animals whose eggs are adjusted for terrestrial living; this group has mammals, reptiles, and birds. Amniotic embryos, occurring in either an externally-shelled egg or one egg lugged by the female, are listed with a water-retaining environment and are safeguarded by amniotic membranes.