Characteristics of Chordata

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

You are watching: A flexible supporting structure found only in chordates is the

Key Takeaways

Key PointsThese features are only present during embryonic advance in some chordates.The notochord provides skeletal support, offers the phylum its name, and also develops into the vertebral column in vertebrates.The dorsal hollow nerve cord establishes into the main nervous system: the mind and spine.Pharyngeal slits room openings in the pharynx that build into gill arcs in bony fish and 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 lacking in humans and apes, although existing during embryonic development.Key Termsnotochord: a functional rodlike structure that forms the key support the the human body in the lowest chordates; a primitive spinenerve cord: a dorsal tubular cord of concerned tissue above the notochord the a chordatepharyngeal slit: filter-feeding organs uncovered in non-vertebrate chordates (lancelets and also tunicates) and hemichordates life in aquatic environments

Characteristics the Chordata

Animals in the phylum Chordata share four an essential features that show up at part stage during their development (often, only during embryogenesis) (:

Defining features of chordates: In chordates, four common features appear at some allude during development: a notochord, a dorsal hole nerve cord, pharyngeal slits, and also 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 found in the embryonic phase of all chordates and additionally in the adult stage of part chordate species. The is located in between the cradle tube and also the nerve cord, giving skeletal assistance through the size of the body. In some chordates, the notochord acts together the primary axial support of the human body throughout the animal’s lifetime.

In vertebrates, the notochord is current during embryonic development, in ~ which time the induces the development of the neural pipe which serves as a support for the developing embryonic body. The notochord, however, is changed by the vertebral obelisk (spine) in many adult vertebrates.

Dorsal hole Nerve Cord

The dorsal hole nerve cord derives native ectoderm that rolls into a hole tube during development. In chordates, that is situated dorsally (at the height of the animal) come the notochord. In contrast to the chordates, other pet phyla are defined by hard nerve cords that are located either ventrally or laterally. The nerve cord found in most chordate embryos creates into the mind and spinal cord, which comprise the central nervous system.

Pharyngeal Slits

Pharyngeal slits space openings in the pharynx (the an ar just posterior come the mouth) that extend to the exterior environment. In organisms that live in aquatic environments, pharyngeal slits permit for the leave of water the enters the mouth during feeding. Part invertebrate chordates usage the pharyngeal slits to filter food out of the water the 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 current only during embryonic development. In this animals, the pharyngeal slits construct into the jaw and also inner ear bones.

Post-anal Tail

The post-anal tail is a posterior elongation that the body, extending past the anus. The tail contains skeletal elements and muscles, which administer a source of locomotion in aquatic species. In part terrestrial vertebrates, the tail additionally helps through balance, courting, and signaling when danger is near. In humans and also other apes, the post-anal tail is present during embryonic development, yet is vestigial together an adult.

Chordates and also the advancement of Vertebrates

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

Key Takeaways

Key PointsUrochordata (tunicates) and also Cephalochordata (lancelets) room invertebrates since they absence a backone.Larval tunicates (Urochordata) posses all 4 structures that classify chordates, but adult tunicates retain only pharyngeal slits.Larval tunicates swim for a few days ~ hatching, then affix to a maritime surface and also undergo metamorphosis right into the sessile adult form.Lancelets (Cephalochordata) are maritime organisms that possess all functions of chordates; lock are called Cephalochordata due to the fact that the notochord extends right into the head.Lancelets might be the closest-living relatives to vertebrates.Key TermsUrochordata: a taxonomic subphylum within the phylum Chordata: the tunicates or sea squirtsCephalochordata: a taxonomic subphylum within the phylum Chordata: the lanceletssessile: permanently attached come a substrate; not totally free to move about; “an attached oyster”

Chordates and also the evolution of Vertebrates

The most acquainted group that chordates is the vertebrates. However, in addition to the subphylum Vertebrata, the phylum Chordata also contains 2 subphylums that invertebrates: Urochordata and Cephalochordata. Members of these groups likewise possess the 4 distinctive features of chordates at some suggest during your development: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail. Unlike vertebrates, urochordates and also cephalochordates never construct a bony backbone.


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

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

Most tunicates are hermaphrodites. Tunicate larvae flower from eggs inside the adult tunicate’s body. After ~ hatching, a tunicate larva swims because that a couple of days till it finds a suitable surface on i beg your pardon it have the right to attach, normally in a dark or shaded location. It climate attaches via the head to the surface and also undergoes metamorphosis into the adult form, in ~ which allude the notochord, nerve cord, and also tail disappear.

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


Members of Cephalochordata own a notochord, dorsal hole nerve cord, pharyngeal slits, and a post-anal tail in the adult stage. They do not have a true brain, yet the notochord extends right into the head, which provides the subphylum its name ( “cephalo” is Greek because that head). Extinction members that this subphylum incorporate Pikaia, i beg your pardon is the oldest recognized cephalochordate. Pikaia fossils to be recovered from the burgess shales of Canada and dated come the middle of the Cambrian age, make them much more than 500 million year old.

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

Cephalochrodates: The lancelet, favor all cephalochordates, has actually a head. Adult lancelets retain the four vital features the chordates: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. Water from the mouth start the pharyngeal slits, which filter the end food particles. The filtered water then collects in the atrium and exits v the atriopore.

Key Takeaways

Key PointsThe clade Craniata includes animals that have actually a cranium: a bony, cartilaginous, or fibrous structure that surrounding the brain, jaw, and facial bones.Members of 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 says that most vertebrate diversity source in the Cambrian explode 540 million years ago.Two whole- genome duplications developed in beforehand vertebrate history.Key Termscranium: the part of the skull enclosing the brain, the braincasegenomics: the research of the complete genome of one organismCambrian explosion: the relatively rapid appearance (over a duration of many millions of years), approximately 530 million year ago, the most major animal phyla together demonstrated in the fossil record

Craniata and Vertebrata

The clade Craniata is a subdivision of Chordata. Members of Craniata posses a cranium, which is a bony, cartilaginous, or fibrous structure neighboring the brain, jaw, and also facial bones. The clade Craniata contains all vertebrates and the hagfishes (Myxini), which have a cranium but lack a backbone. Hagfish are the only known living animals that have actually a skull, however not a vertebral column.


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

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

Vertebrates: Vertebrata are defined by the existence of a backbone, such together the one that runs v the middle of this fish. All vertebrates are in the Craniata clade and have a cranium.

Vertebrate Evolution

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

According to these genomic analyses, vertebrates appear to be more closely pertained to the lancelets (cephalochordates) than to the tunicates (urochordates). This suggests that the cephalochordates very first diverged from urochordates, and that vertebrates ultimately diverged indigenous the cephalochordates. This theory is additional supported by the fossil that a 530 million-year-old organism through a mind and eyes choose a vertebrate, however without the skull discovered in a craniate. A compare of the genomes the a lancelet, tunicate, lamprey, fish, chicken, and human confirmed that two whole-genome duplications developed in the early history of the Vertebrata subphylum.

Both fossil and also genomic evidence argues that vertebrates arose during the Cambrian explosion.The Cambrian explosion to be the reasonably brief span of time throughout the Cambrian duration during which many animal groups appeared and rapidly diversified. Most modern-day animal phyla originated during the Cambrian explosion.

Characteristics of Vertebrates

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

Key Takeaways

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

Characteristics that 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 divided into 2 groups, protostomes and also deuterostomes, based upon their patterns of embryonic development. The deuterostomes, who name equates as “second mouth,” consists of two phyla: Chordata and also Echinodermata. Echinoderms are invertebrate marine animals that have actually pentaradial symmetry and a spiny human body covering; the phylum contains sea stars, sea urchins, and also sea cucumbers. The phylum Chordata has two teams of invertebrate chordates, however the many conspicuous and familiar members that Chordata are the vertebrates.

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

As chordates, all vertebrates have a similar anatomy and also morphology with 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 by the advance of the notochord into a bony backbone. Vertebrates include the amphibians, reptiles, mammals, and birds, and the jawless fishes, bony fishes, sharks, and rays.

Diversity of vertebrates: pets with backbones: The subphylum Vertebrata includes all pets that possess backbones, gills, and also a main nervous device in at least one step of development. Vertebrates encompass amphibians, reptiles, mammals, and birds, as well as the jawless fishes, bony fishes, sharks, and rays.

More 보다 64,000 species of vertebrates have been described, but the extant vertebrate species represent only a small part of all the vertebrates that have actually existed. Vertebrates variety in dimension from the frog species Paedophryne amauensis (as little as 7.7 mm (0.3 inch)) come the blue whale (as huge as 33 m (110 ft)). Vertebrates comprise around 4 percent of every described animal species; the remainder space invertebrates, which lack backbones.

Anatomy and also Morphology

All vertebrates are built along the basic chordate human body plan: a stubborn rod running through the size of the pet (vertebral column), v a hollow tube the nervous tissue (the spinal cord) above it and the gastrointestinal tract below. In all vertebrates, there is a mouth at anterior finish of the animal and also an anus prior to the posterior end of the body. There is a tail posterior come 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 creates into the vertebral tower or spine: a collection of bony vertebrae each separated through mobile discs. This vertebrae are always found top top the dorsal next of the animal. However, a couple of vertebrates have actually secondarily lost their vertebrae and, instead, retain the notochord into adulthood (e.g., the sturgeon fish).


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

Central nervous System

Vertebrates are likewise the just members the Chordata to possess a brain. In chordates, the central nervous system is based on a hole nerve tube the runs dorsal to the notochord along the size of the animal. In vertebrates, the anterior end of the nerve pipe expands and also differentiates right into three brain vesicles.

Vertebrate Classification

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

See more: A Rectangle Which Is Equilateral Is A, Quadrilaterals Flashcards

Animals that possess jaws are recognized as gnathostomes, definition “jawed mouth.” Gnathostomes encompass fishes and also tetrapods (amphibians, reptiles, birds, and also mammals). Tetrapods have the right to be further separated into 2 groups: amphibians and also amniotes. Amniotes are pets whose egg are adjusted for terrestrial living; this group includes mammals, reptiles, and birds. Amniotic embryos, emerging in either an externally-shelled egg or one egg brought by the female, are listed with a water-retaining environment and also are safeguarded by amniotic membranes.