Characteristics of Chordata

Animals in the phylum Chordata re-publishing four key features: a notochord, a dorsal hole 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 part chordates.The notochord gives skeletal support, provides the phylum the name, and develops right into the vertebral obelisk in vertebrates.The dorsal hole nerve cord creates into the central nervous system: the mind and spine.Pharyngeal slits are openings in the pharynx that construct into gill arcs in bony fish and also into the jaw and also inner ear in terrestrial animals.The post-anal tail is a skeletal expansion of the posterior finish of the body, being absent in humans and also apes, although existing during embryonic development.Key Termsnotochord: a flexible rodlike framework that develops the main support of the body in the lowest chordates; a primitive spinenerve cord: a dorsal tubular cord of worried tissue over the notochord the a chordatepharyngeal slit: filter-feeding organs uncovered in non-vertebrate chordates (lancelets and tunicates) and hemichordates living in aquatic environments

Characteristics that Chordata

Animals in the phylum Chordata re-superstructure four vital features that appear at some stage throughout their advancement (often, only during embryogenesis) (:

Defining attributes of chordates: In chordates, four common features appear 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 called for the notochord: a flexible, rod-shaped structure that is found in the embryonic phase of all chordates and also in the adult stage of part chordate species. The is located between the digestive tube and also the nerve cord, providing skeletal support through the size of the body. In some chordates, the notochord acts together the major axial support of the human body throughout the animal’s lifetime.

In vertebrates, the notochord is existing during embryonic development, in ~ which time that induces the advance of the neural pipe which serves as a assistance for the developing embryonic body. The notochord, however, is changed by the vertebral column (spine) in most adult vertebrates.

Dorsal hole Nerve Cord

The dorsal hollow nerve cord derives native ectoderm that rolls into a hole tube throughout development. In chordates, that is situated dorsally (at the top of the animal) come the notochord. In contrast to the chordates, other animal phyla are defined by heavy nerve cords that are located either ventrally or laterally. The nerve cord uncovered in most chordate embryos establishes into the mind and spinal cord, which make up the central nervous system.

Pharyngeal Slits

Pharyngeal slits space openings in the pharynx (the an ar just posterior come the mouth) that prolong to the exterior environment. In organisms the live in aquatic environments, pharyngeal slits permit for the exit of water the enters the mouth throughout feeding. Some invertebrate chordates usage the pharyngeal slits to filter food out 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, including mammals and also birds, pharyngeal slits are existing only during 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 of the body, extending past the anus. The tail consists of skeletal elements and also muscles, which carry out a source of locomotion in aquatic species. In some terrestrial vertebrates, the tail additionally helps through balance, courting, and also signaling once danger is near. In humans and other apes, the post-anal tail is present during embryonic development, however is vestigial as an adult.

Chordates and also the advancement of Vertebrates

Chordata consists of two subphylums the invertebrates: Urochordata (tunicates) and Cephalochordata (lancelets).

Key Takeaways

Key PointsUrochordata (tunicates) and Cephalochordata (lancelets) room invertebrates because they lack a backone.Larval tunicates (Urochordata) posses all four structures that classify chordates, but adult tunicates retain only pharyngeal slits.Larval tunicates swim because that a few days after hatching, then affix to a maritime surface and also undergo metamorphosis into the sessile adult form.Lancelets (Cephalochordata) are marine organisms that possess all attributes of chordates; lock are named Cephalochordata since the notochord extends into the head.Lancelets may be the closest-living relatives to vertebrates.Key TermsUrochordata: a taxonomic subphylum within the phylum Chordata: the tunicates or sea squirtsCephalochordata: a taxonomic subphylum in ~ the phylum Chordata: the lanceletssessile: permanently attached come a substrate; not totally free to relocate about; “an enclosed oyster”

Chordates and also the development of Vertebrates

The most acquainted group that chordates is the vertebrates. However, in addition to the subphylum Vertebrata, the phylum Chordata also contains two subphylums that invertebrates: Urochordata and also Cephalochordata. Members of this groups likewise 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 also cephalochordates never construct a bony backbone.


Members the Urochordata are likewise known together tunicates. The surname tunicate derives indigenous the cellulose-like carbohydrate material, called the tunic, i beg your pardon covers the outer body the tunicates. Back tunicates are classified together chordates, only the larval type possesses all four usual structures. Adult only maintain pharyngeal slits and also lack a notochord, a dorsal hollow nerve cord, and a post-anal tail.

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

Most tunicates space hermaphrodites. Tunicate larvae hatch from eggs within the adult tunicate’s body. After hatching, a tunicate larva swims for a few days till it find a perfect surface on i beg your pardon it deserve to attach, commonly in a dark or shaded location. It climate attaches via the head to the surface and undergoes metamorphosis into the adult form, at which suggest the notochord, nerve cord, and tail disappear.

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


Members the Cephalochordata own a notochord, dorsal hollow nerve cord, pharyngeal slits, and also a post-anal tail in the adult stage. They carry out not have a true brain, yet the notochord extends right into the head, which provides the subphylum its surname ( “cephalo” is Greek for head). Extinct members the this subphylum include Pikaia, which is the oldest well-known cephalochordate. Pikaia fossils were recovered from the citizen shales that Canada and dated come the center of the Cambrian age, do them more than 500 million year old.

Extant members that Cephalochordata room the lancelets, named for your blade-like shape. Lancelets are just a few centimeters long and also are generally found buried in sand in ~ the bottom of warm temperate and tropical seas. Prefer tunicates, they room suspension feeders. With notochord and paired muscle blocks, the lancelet and Pikaia might belong come the chordate team of animals from i m sorry the vertebrates have descended.

Cephalochrodates: The lancelet, choose all cephalochordates, has actually a head. Adult lancelets retain the four key features the chordates: a notochord, a dorsal hole nerve cord, pharyngeal slits, and also a post-anal tail. Water indigenous the mouth beginning the pharyngeal slits, i beg your pardon filter out food particles. The filtered water climate collects in the atrium and exits v the atriopore.

Key Takeaways

Key PointsThe clade Craniata includes pets that have actually a cranium: a bony, cartilaginous, or fibrous structure that surrounds the brain, jaw, and facial bones.Members of Craniata encompass the vertebrates and also hagfish.Genomic evidence suggests that vertebrates diverged from cephalochordates (lancelets), which had previously diverged from urochordates (tunicates).Fossil evidence suggests that most vertebrate diversity source in the Cambrian explode 540 million year ago.Two whole- genome duplications emerged in beforehand vertebrate history.Key Termscranium: the part of the skull enclosing the brain, the braincasegenomics: the examine of the complete genome of one organismCambrian explosion: the reasonably rapid figure (over a duration of plenty of millions the years), about 530 million year ago, the most significant animal phyla together 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 surrounding the brain, jaw, and also facial bones. The clade Craniata contains all vertebrates and the hagfishes (Myxini), which have actually a cranium but lack a backbone. Hagfish are the only recognized living pets that have actually a skull, yet not a vertebral column.


Hagfish: Although that 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 existence of a cranium, mandible, and other facial bones.

Vertebrates: Vertebrata are identified by the visibility of a backbone, such as the one that runs with the center of this fish. Every vertebrates space in the Craniata clade and have a cranium.

Vertebrate Evolution

In the phylum Chordata, the closest family members of the vertebrates space the invertebrate chordates. Based upon the molecular evaluation of vertebrate and also invertebrate genomes (genomics), scientists have the right to determine the evolutionary history of different phylogenetic groups.

According to this genomic analyses, vertebrates show up to be an ext closely regarded the lancelets (cephalochordates) 보다 to the tunicates (urochordates). This says that the cephalochordates very first diverged native urochordates, and that vertebrates ultimately diverged indigenous the cephalochordates. This hypothesis is additional supported through the fossil of a 530 million-year-old organism v a brain and eyes choose a vertebrate, but without the skull uncovered in a craniate. A to compare of the genomes that a lancelet, tunicate, lamprey, fish, chicken, and human confirmed that two whole-genome duplications arisen in the early history of the Vertebrata subphylum.

Both fossil and genomic evidence suggests that vertebrates arose during the Cambrian explosion.The Cambrian explosion was the reasonably brief expectations of time throughout the Cambrian period during which many pet groups appeared and also rapidly diversified. Most modern-day animal phyla originated throughout the Cambrian explosion.

Characteristics the Vertebrates

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

Key Takeaways

Key PointsAs chordates, vertebrates have actually the same typical features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.Vertebrates are further differentiated from chordates by your vertebral column, which develops when their notochord establishes into the tower of bony vertebrae be separate by discs.Vertebrates room the only chordates that have a mind as part of their main nervous system.Key Termsvertebral column: the collection of vertebrae that safeguard the spinal cord; the spinal columnchordate: a member the the phylum Chordata; numerous pets having a notochord at some phase of your development; in vertebrates this establishes into the spinenotochord: a flexible rodlike framework that forms the main support the the human body in the shortest chordates; a primitive spine

Characteristics the Vertebrates

Vertebrates space members of the subphylum Vertebrata, under the phylum Chordata and also under the kingdom Animalia. Animals that possess bilateral symmetry deserve to be divided into 2 groups, protostomes and also deuterostomes, based on their patterns of embryonic development. The deuterostomes, who name equates as “second mouth,” consists of two phyla: Chordata and Echinodermata. Echinoderms room invertebrate marine animals that have actually pentaradial symmetry and also a spiny human body covering; the phylum contains sea stars, sea urchins, and also sea cucumbers. The phylum Chordata has two groups of invertebrate chordates, yet the many conspicuous and familiar members the Chordata space the vertebrates.

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

As chordates, every vertebrates have a similar anatomy and also morphology with the exact 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 through the advance of the notochord right into a bony backbone. Vertebrates encompass the amphibians, reptiles, mammals, and also birds, as well as the jawless fishes, bony fishes, sharks, and also rays.

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

More than 64,000 varieties of vertebrates have actually been described, but the extant vertebrate species represent just a small part of every the vertebrates that have existed. Vertebrates variety in dimension from the frog species Paedophryne amauensis (as tiny as 7.7 mm (0.3 inch)) to the blue whale (as big as 33 m (110 ft)). Vertebrates comprise about 4 percent of every described animal species; the remainder space invertebrates, which absence backbones.

Anatomy and also Morphology

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

The Vertebral Column

Vertebrates are defined by the visibility of the vertebral column. In vertebrates, the notochord creates into the vertebral shaft or spine: a collection of bony vertebrae every separated by mobile discs. These vertebrae are constantly found ~ above the dorsal next of the animal. However, a couple of 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 severe example of the backbone that characterizes vertebrates.

Central concerned System

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

Vertebrate Classification

Vertebrates space the largest team of chordates, with more than 62,000 living species. Vertebrates are grouped based on anatomical and physiological traits. The timeless groups include Agnatha, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia.

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Animals that possess jaws are well-known as gnathostomes, meaning “jawed mouth.” Gnathostomes include fishes and also tetrapods (amphibians, reptiles, birds, and mammals). Tetrapods can be further split into two groups: amphibians and amniotes. Amniotes are animals whose egg are adapted for terrestrial living; this group contains mammals, reptiles, and also birds. Amniotic embryos, occurring in one of two people an externally-shelled egg or an egg lugged by the female, are listed with a water-retaining environment and are defended by amniotic membranes.