Characteristics that Chordata

Animals in the phylum Chordata re-superstructure 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 current during embryonic development in part chordates.The notochord provides skeletal support, provides the phylum its name, and develops right into the vertebral column in vertebrates.The dorsal hole nerve cord establishes into the central nervous system: the mind and spine.Pharyngeal slits space openings in the pharynx that construct 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 missing in humans and also apes, although present during embryonic development.Key Termsnotochord: a versatile rodlike structure that creates the main support the the human body in the lowest chordates; a primitive spinenerve cord: a dorsal tubular cord of worried tissue above the notochord of a chordatepharyngeal slit: filter-feeding organs discovered in non-vertebrate chordates (lancelets and tunicates) and hemichordates life in aquatic environments

Characteristics of Chordata

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

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

a notochorda dorsal hole nerve cordpharyngeal slitspost-anal tail


The chordates are called for the notochord: a flexible, rod-shaped structure that is uncovered in the embryonic stage of every chordates and additionally in the adult phase of some chordate species. It is located between the cradle tube and the nerve cord, offering skeletal support through the length of the body. In part chordates, the notochord acts together the main axial support of the human body throughout the animal’s lifetime.

In vertebrates, the notochord is existing during embryonic development, at which time the induces the breakthrough of the neural tube which serves as a assistance for the emerging embryonic body. The notochord, however, is replaced by the vertebral column (spine) in most adult vertebrates.

Dorsal hollow Nerve Cord

The dorsal hollow nerve cord derives native ectoderm that rolls right into a hollow tube during development. In chordates, it is located dorsally (at the top of the animal) to the notochord. In comparison to the chordates, other animal phyla are identified by hard nerve cords that are situated either ventrally or laterally. The nerve cord uncovered in most chordate embryos creates into the mind and spinal cord, which comprise 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 external environment. In organisms that live in aquatic environments, pharyngeal slits permit for the leave of water that enters the mouth during feeding. Some invertebrate chordates use 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, consisting of mammals and birds, pharyngeal slits are present 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 that the body, extending past the anus. The tail includes skeletal elements and muscles, which carry out a resource of locomotion in aquatic species. In part terrestrial vertebrates, the tail additionally helps through balance, courting, and signaling once danger is near. In humans and also other apes, the post-anal tail is existing during embryonic development, yet is vestigial together an adult.

Chordates and the evolution of Vertebrates

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

Key Takeaways

Key PointsUrochordata (tunicates) and also Cephalochordata (lancelets) are invertebrates due to the fact that they lack a backone.Larval tunicates (Urochordata) posses all 4 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 naval surface and also undergo metamorphosis right into the sessile adult form.Lancelets (Cephalochordata) are maritime organisms that possess all features of chordates; castle are called Cephalochordata since the notochord extends right 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 to a substrate; not complimentary to relocate about; “an fastened oyster”

Chordates and also the development of Vertebrates

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


Members the Urochordata are additionally known as tunicates. The surname tunicate derives indigenous the cellulose-like carbohydrate material, called the tunic, which covers the external body that tunicates. Return tunicates are classified together chordates, only 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 photo shows a swarm of the tunicate Botrylloides violaceus. (b) The larval phase of the tunicate possesses every one of the features characteristic that 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 flower from eggs within the adult tunicate’s body. After hatching, a tunicate larva swims for a couple of days till it find a an ideal surface on i beg your pardon it have the right to attach, typically 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 ocean floor and are suspension feeders. The primary foods items of tunicates space plankton and detritus. Seawater start the tunicate’s body through its incurrent siphon. Suspended product 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 into the excurrent siphon, which expulsion wastes and water. Tunicates are uncovered in shallow ocean waters approximately 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 do not have a true brain, but the notochord extends into the head, which offers the subphylum its name ( “cephalo” is Greek for head). Extinction members that this subphylum encompass Pikaia, i beg your pardon is the oldest well-known cephalochordate. Pikaia fossils were recovered indigenous the burgess shales of Canada and dated to the center of the Cambrian age, do them an ext than 500 million year old.

Extant members the Cephalochordata are the lancelets, called for your blade-like shape. Lancelets are just a couple of centimeters long and are typically found buried in sand at the bottom of heat temperate and also tropical seas. Favor tunicates, they space suspension feeders. With notochord and also paired muscle blocks, the lancelet and also Pikaia may belong to the chordate group 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 hollow nerve cord, pharyngeal slits, and also a post-anal tail. Water indigenous the mouth enters the pharyngeal slits, i m sorry filter out 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 structure that surrounding the brain, jaw, and facial bones.Members that Craniata encompass the vertebrates and hagfish.Genomic evidence argues that vertebrates diverged from cephalochordates (lancelets), which had actually previously diverged from urochordates (tunicates).Fossil evidence suggests that many vertebrate diversity originated in the Cambrian explosion 540 million years ago.Two whole- genome duplications developed in early vertebrate history.Key Termscranium: the part of the skull enclosing the brain, the braincasegenomics: the study of the complete genome of one organismCambrian explosion: the reasonably rapid appearance (over a duration of plenty of millions that years), around 530 million years ago, that most significant animal phyla together demonstrated in the fossil record

Craniata and Vertebrata

The clade Craniata is a subdivision the Chordata. Members of Craniata posses a cranium, i beg your pardon is a bony, cartilaginous, or fibrous structure neighboring 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 animals that have a skull, yet not a vertebral column.


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

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

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

Vertebrate Evolution

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

According to these genomic analyses, vertebrates appear to be an ext closely related to the lancelets (cephalochordates) 보다 to the tunicates (urochordates). This says that the cephalochordates first diverged from urochordates, and also that vertebrates subsequently diverged from the cephalochordates. This theory is additional supported through the fossil of a 530 million-year-old organism v a brain and eyes like a vertebrate, but without the skull uncovered in a craniate. A to compare of the genomes the a lancelet, tunicate, lamprey, fish, chicken, and also human evidenced that two whole-genome duplications arisen in the early background of the Vertebrata subphylum.

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

Characteristics of Vertebrates

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

Key Takeaways

Key PointsAs chordates, vertebrates have the same common features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.Vertebrates space further distinguished from chordates by their vertebral column, which creates when your notochord establishes into the tower of bony vertebrae be separate by discs.Vertebrates room the only chordates that have actually a mind as part of their main nervous system.Key Termsvertebral column: the series of vertebrae that protect the spinal cord; the spinal columnchordate: a member of the phylum Chordata; numerous animals having a notochord in ~ some phase of their development; in vertebrates this establishes into the spinenotochord: a versatile rodlike structure that creates the main support the the human body in the lowest chordates; a primitive spine

Characteristics of Vertebrates

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

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

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

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

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

Anatomy and also Morphology

All vertebrates are developed along the straightforward chordate human body plan: a stubborn rod running v the length of the animal (vertebral column), with a hollow tube of nervous organization (the spinal cord) above it and the gastrointestinal street below. In all vertebrates, there is a mouth in ~ 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 throughout at the very least one phase of the animal’s development.

The Vertebral Column

Vertebrates are identified by the existence of the vertebral column. In vertebrates, the notochord establishes into the vertebral obelisk or spine: a series of bony vertebrae every separated by mobile discs. These vertebrae are constantly found ~ above the dorsal side of the animal. However, a couple of vertebrates have secondarily shed their vertebrae and, instead, maintain the notochord into adulthood (e.g., the sturgeon fish).


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

Central nervous System

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

Vertebrate Classification

Vertebrates space the largest group of chordates, with an ext than 62,000 life species. Vertebrates room grouped based on 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 recognized as gnathostomes, definition “jawed mouth.” Gnathostomes incorporate fishes and tetrapods (amphibians, reptiles, birds, and also mammals). Tetrapods deserve to be further split into 2 groups: amphibians and amniotes. Amniotes are animals whose egg are adjusted for terrestrial living; this group consists of mammals, reptiles, and birds. Amniotic embryos, occurring in either an externally-shelled egg or an egg carried by the female, are detailed with a water-retaining environment and also are defended by amniotic membranes.