Characteristics of Chordata

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

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Key Takeaways

Key PointsThese characteristics are only current in the time of embryonic advancement in some chordates.The notochord gives skeletal support, offers the phylum its name, and creates into the vertebral column in vertebrates.The dorsal hollow nerve cord develops right into the main nervous system: the brain and spine.Pharyngeal slits are openings in the pharynx that build into gill arches in bony fish and right into the jaw and also inner ear in terrestrial pets.The post-anal tail is a skeletal extension of the posterior end of the body, being lacking in humans and apes, although present throughout embryonic development.Key Termsnotochord: a functional rodlike structure that develops the major assistance of the body in the lowest chordates; a primitive spinenerve cord: a dorsal tubular cord of nervous tconcern above the notochord of a chordatepharyngeal slit: filter-feeding organs uncovered in non-vertebrate chordates (lanceallows and tunicates) and hemichordays living in aquatic environments

Characteristics of Chordata

Animals in the phylum Chordata share four key features that appear at some phase in the time of their breakthrough (frequently, just in the time of embryogenesis) (:

Defining attributes of chordates: In chordays, 4 prevalent features appear at some point during development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

a notochorda dorsal hollow nerve cordpharyngeal slitspost-anal tail


The chordays are named for the notochord: a flexible, rod-shaped structure that is discovered in the embryonic phase of all chordates and also in the adult phase of some chorday species. It is situated in between the digestive tube and also the nerve cord, offering skeletal support via the size of the body. In some chordays, the notochord acts as the main axial support of the body throughout the animal’s life time.

In vertebrates, the notochord is current during embryonic advance, at which time it induces the development of the neural tube which serves as a assistance for the occurring embryonic body. The notochord, but, is reinserted by the vertebral column (spine) in most adult vertebprices.

Dorsal Hollow Nerve Cord

The dorsal hollow nerve cord derives from ectoderm that rolls right into a hollow tube during development. In chordays, it is situated dorsally (at the peak of the animal) to the notochord. In contrast to the chordates, other animal phyla are identified by solid nerve cords that are located either ventrally or laterally. The nerve cord uncovered in a lot of chordate embryos establishes into the brain and spinal cord, which comprise the central nervous device.

Pharyngeal Slits

Pharyngeal slits are openings in the pharynx (the region simply posterior to the mouth) that extend to the exterior atmosphere. In organisms that live in aquatic atmospheres, pharyngeal slits permit for the departure of water that enters the mouth throughout feeding. Some invertebprice chordates usage the pharyngeal slits to filter food out of the water that enters the mouth. In vertebprice fishes, the pharyngeal slits construct right into gill arcs, the bony or cartilaginous gill supports.

In a lot of terrestrial pets, including mammals and also birds, pharyngeal slits are existing just in the time of embryonic breakthrough. In these pets, the pharyngeal slits develop right into the jaw and also inner ear bones.

Post-anal Tail

The post-anal tail is a posterior elongation of the body, extfinishing past the anus. The tail consists of skeletal facets and also muscles, which administer a source of locomovement in aquatic species. In some terrestrial vertebprices, the tail also helps through balance, courting, and also signaling as soon as danger is close to. In people and other apes, the post-anal tail is present during embryonic development, yet is vestigial as an adult.

Chordays and also the Evolution of Vertebrates

Chorinformation has two subphylums of invertebrates: Urochordata (tunicates) and also Cephalochordata (lancelets).

Key Takeaways

Key PointsUrochorinformation (tunicates) and also Cephalochorinformation (lancelets) are 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 for a couple of days after hatching, then connect to a marine surconfront and also undergo metamorphosis into the sessile adult create.Lanceallows (Cephalochordata) are marine organisms that possess all functions of chordates; they are called Cephalochorinformation bereason the notochord exoften tends into the head.Lanceallows might be the closest-living family members 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 to a substrate; not totally free to move about; “an attached oyster”

Chordates and the Evolution of Vertebrates

The a lot of familiar group of chordates is the vertebprices. However before, in enhancement to the subphylum Vertebrata, the phylum Chordata additionally has 2 subphylums of invertebrates: Urochorinformation and also Cephalochorinformation. Members of these groups also possess the 4 distinctive attributes of chordates at some point in the time of their development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and also a post-anal tail. Unfavor vertebprices, urochordays and also cephalochordates never construct a bony backbone.


Members of Urochorinformation are likewise recognized as tunicates. The name tunicate derives from the cellulose-prefer carbohydrate product, called the tunic, which covers the outer body of tunicates. Although tunicates are classified as chordates, only the larval develop possesses all 4 prevalent frameworks. Adults just maintain pharyngeal slits and lack a notochord, a dorsal hollow nerve cord, and a post-anal tail.

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

Many tunicates are hermaphrodites. Tunicate larvae hatch from eggs inside the adult tunicate’s body. After hatching, a tunicate larva swims for a couple of days until it finds a perfect surconfront on which it have the right to affix, generally in a dark or shaded place. It then attaches through the head to the surconfront and also undergoes metamorphosis into the adult create, at which allude the notochord, nerve cord, and tail disappear.

Many tunicates live a sessile presence on the ocean floor and also are suspension feeders. The major foods of tunicates are plankton and also detritus. Seawater enters the tunicate’s body via its inexisting siphon. Suspfinished product is filtered out of this water by a mucous net (pharyngeal slits) and is passed into the intestine by means of the activity of cilia. The anus empties into the exexisting siphon, which expels wastes and water. Tunicates are uncovered in shallow sea waters roughly the world.


Members of Cephalochordata possess a notochord, dorsal hollow nerve cord, pharyngeal slits, and also a post-anal tail in the adult phase. They carry out not have a true brain, yet the notochord exhas a tendency into the head, which provides the subphylum its name ( “cephalo” is Greek for head). Extinct members of this subphylum include Pikaia, which is the oldest well-known cephalochorday. Pikaia fossils were recovered from the Burgess shales of Canada and also dated to the middle of the Cambria period, making them more than 500 million years old.

Extant members of Cephalochorinformation are the lanceallows, named for their blade-like form. Lancelets are just a few centimeters long and are generally discovered buried in sand also at the bottom of heat temperate and also tropical seas. Like tunicates, they are suspension feeders. With notochord and paired muscle blocks, the lancelet and also Pikaia may belong to the chordate team of pets from which the vertebrates have descfinished.

Cephalochrodates: The lancelet, choose all cephalochordays, has actually a head. Adult lanceallows retain the four crucial attributes of chordates: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. Water from the mouth enters the pharyngeal slits, which filter out food pwrite-ups. The filtered water then collects in the atrium and also exits via the atriopore.

Key Takeaways

Key PointsThe clade Craniata consists of animals that have a cranium: a bony, cartilaginous, or fibrous structure that surrounds the brain, jaw, and also facial bones.Members of Craniata incorporate the vertebrates and hagfish.Genomic proof suggests that vertebprices diverged from cephalochordates (lancelets), which had actually previously diverged from urochordates (tunicates).Fossil evidence says that the majority of vertebrate diversity originated in the Cambrian explosion 540 million years ago.Two whole- genome duplications emerged in beforehand vertebprice history.Key Termscranium: the part of the skull enclosing the brain, the braincasegenomics: the research of the complete genome of an organismCambrian explosion: the fairly quick appearance (over a period of many numerous years), around 530 million years back, of the majority of major pet phyla as demonstrated in the fossil record

Craniata and also Vertebrata

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


Hagfish: Although it lacks a backbone, the hagfish is a member of the Craniata clade bereason it possesses a bony skull.

Clade Craniata: Craniata, consisting of this fish (Dunkleosteus), are defined by the visibility of a cranium, mandible, and other facial bones.

Vertebrates: Vertebrata are identified by the visibility of a backbone, such as the one that runs via the middle 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 are the invertebrate chordates. Based on the molecular evaluation of vertebprice and invertebprice genomes (genomics), researchers have the right to recognize the evolutionary background of various phylogenetic teams.

According to these genomic analyses, vertebrates show up to be even more carefully related to the lanceallows (cephalochordates) than to the tunicates (urochordates). This argues that the cephalochordays first diverged from urochordays, and also that vertebprices subsequently diverged from the cephalochordates. This hypothesis is even more supported by the fossil of a 530 million-year-old organism through a mind and eyes like a vertebprice, yet without the skull found in a craniate. A comparikid of the genomes of a lancelet, tunicate, lamprey, fish, chicken, and also human evidenced that 2 whole-genome duplications arisen in the early on history of the Vertebrata subphylum.

Both fossil and genomic evidence suggests that vertebrates emerged throughout the Cambrian explosion.The Cambrian explosion was the reasonably brief expectancy of time in the time of the Cambrian duration in the time of which many type of animal groups showed up and also swiftly diversified. Many modern animal phyla originated in the time of the Cambrian explosion.

Characteristics of Vertebrates

Vertebrata is a subphlyum of Chorinformation that is further defined by their bony backbone.

Key Takeaways

Key PointsAs chordates, vertebrates have actually the very same common features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and also a post-anal tail.Vertebrates are further differentiated from chordays by their vertebral column, which creates once their notochord creates right into the column of bony vertebrae separated by discs.Vertebrates are the just chordates that have actually a brain as part of their main nervous system.Key Termsvertebral column: the series of vertebrae that defend the spinal cord; the spinal columnchordate: a member of the phylum Chordata; plenty of animals having actually a notochord at some stage of their development; in vertebprices this develops into the spinenotochord: a versatile rodprefer framework that forms the main assistance of the body in the lowest chordates; a primitive spine

Characteristics of Vertebrates

Vertebprices are members of the subphylum Vertebrata, under the phylum Chordata and also under the kingdom Animalia. Animals that possess bilateral symmeattempt have the right to be split right into two teams, protostomes and also deuterostomes, based on their trends of embryonic development. The deuterostomes, whose name translates as “second mouth,” consist of 2 phyla: Chorinformation and Echinodermata. Echinoderms are invertebrate marine pets that have actually pentaradial symmetry and a spiny body covering; the phylum contains sea stars, sea urchins, and also sea cucumbers. The phylum Chordata has two teams of invertebprice chordays, however the the majority of conspicuous and also familiar members of Chorinformation are the vertebprices.

Phylum chordata: All chordays are deuterostomes, possessing a notochord. Vertebrates are identified by having a vertebral column.

As chordates, all vertebprices have actually a comparable anatomy and also morphology through the exact same qualifying characteristics: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and also a post-anal tail. However, the subphylum Vertebrata is distinguimelted from the phylum Chordata by the breakthrough of the notochord into a bony backbone. Vertebprices encompass the amphibians, reptiles, mammals, and birds, as well as the jawless fishes, bony fishes, sharks, and rays.

Diversity of vertebrates: animals through backbones: The subphylum Vertebrata consists of all animals that possess backbones, gills, and also a central nervous system in at least one phase of advance. Vertebrates encompass amphibians, reptiles, mammals, and also birds, as well as the jawless fishes, bony fishes, sharks, and also rays.

More than 64,000 species of vertebrates have been explained, but the extant vertebprice species recurrent just a tiny portion of all the vertebprices that have actually existed. Vertebrates array in dimension from the frog species Paedophryne amauensis (as small as 7.7 mm (0.3 inch)) to the blue whale (as large as 33 m (110 ft)). Vertebrates comprise around 4 percent of all described pet species; the remainder are invertebrates, which absence backbones.

Anatomy and also Morphology

All vertebprices are developed along the fundamental chordate body plan: a stiff rod running through the length of the animal (vertebral column), through a hollow tube of nervous tworry (the spinal cord) above it and the gastrointestinal tract listed below. In all vertebprices, there is a mouth at anterior finish of the pet and also an anus before the posterior end of the body. Tright here is a tail posterior to the anus during at leastern one phase of the animal’s development.

The Vertebral Column

Vertebrates are characterized by the existence of the vertebral column. In vertebrates, the notochord establishes into the vertebral column or spine: a collection of bony vertebrae each separated by mobile discs. These vertebrae are constantly found on the dorsal side of the pet. However before, a few vertebprices have actually secondarily shed their vertebrae and also, rather, retain the notochord right into adulthood (e.g., the sturgeon fish).


Vertebral column: A fossilized skeleton of the dinosaur Diplodocus carnegii reflects an extreme instance of the backbone that characterizes vertebprices.

Central Nervous System

Vertebprices are likewise the just members of Chorinformation to possess a brain. In chordates, the main nervous system is based upon a hollow nerve tube that runs dorsal to the notochord along the length of the animal. In vertebrates, the anterior end of the nerve tube expands and also differentiates right into 3 brain vesicles.

Vertebprice Classification

Vertebrates are the largest group of chordates, through even more than 62,000 living species. Vertebrates are grouped based on anatomical and also physiological traits. The typical teams encompass Agnatha, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia.

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Animals that possess jaws are recognized as gnathostomes, definition “jawed mouth.” Gnathostomes include fishes and tetrapods (amphibians, reptiles, birds, and mammals). Tetrapods have the right to be better separated right into two groups: amphibians and also amniotes. Amniotes are pets whose eggs are adjusted for terrestrial living; this group consists of mammals, reptiles, and also birds. Amniotic embryos, emerging in either an externally-shelled egg or an egg carried by the female, are provided via a water-retaining atmosphere and are protected by amniotic membranes.