Characteristics the Chordata

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

You are watching: Which of the following is not a diagnostic feature of the chordata?

Key Takeaways

Key PointsThese features are only existing during embryonic breakthrough in part chordates.The notochord offers skeletal support, offers the phylum the name, and develops into the vertebral pillar 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 build 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 extension of the posterior end of the body, being missing in humans and also apes, although current during embryonic development.Key Termsnotochord: a versatile rodlike framework that creates the main support that the body in the lowest chordates; a primitive spinenerve cord: a dorsal tubular cord of nervous tissue above the notochord of a chordatepharyngeal slit: filter-feeding organs discovered in non-vertebrate chordates (lancelets and tunicates) and hemichordates living in aquatic environments

Characteristics that Chordata

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

Defining qualities of chordates: In chordates, four common features appear at some allude during development: a notochord, a dorsal hollow 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 discovered in the embryonic stage of all chordates and additionally in the adult stage of part chordate species. It is located between the cradle tube and also the nerve cord, providing skeletal support through the size of the body. In part chordates, the notochord acts as the main axial support of the human body throughout the animal’s lifetime.

In vertebrates, the notochord is current during embryonic development, in ~ which time it induces the breakthrough of the neural tube which serves as a assistance for the arising embryonic body. The notochord, however, is changed by the vertebral obelisk (spine) in most adult vertebrates.

Dorsal hollow Nerve Cord

The dorsal hole nerve cord derives indigenous ectoderm the rolls right into a hollow tube throughout development. In chordates, the is located dorsally (at the height of the animal) come the notochord. In contrast to the chordates, other pet phyla are identified by hard nerve cords that are located either ventrally or laterally. The nerve cord discovered in most chordate embryos develops into the brain and spinal cord, which consist of the central nervous system.

Pharyngeal Slits

Pharyngeal slits room openings in the pharynx (the region just posterior come the mouth) that expand to the external 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 come filter food the end of the water the enters the mouth. In vertebrate fishes, the pharyngeal slits build into gill arches, the bony or cartilaginous gill supports.

In many terrestrial animals, consisting of mammals and birds, pharyngeal slits are current only during embryonic development. In this animals, the pharyngeal slits build 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 consists of skeletal elements and muscles, which carry out a resource of locomotion in aquatic species. In some terrestrial vertebrates, the tail likewise helps with balance, courting, and also signaling as soon as danger is near. In humans and other apes, the post-anal tail is current during embryonic development, however is vestigial as an adult.

Chordates and the advancement of Vertebrates

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

Key Takeaways

Key PointsUrochordata (tunicates) and also Cephalochordata (lancelets) space invertebrates due to the fact that they absence a backone.Larval tunicates (Urochordata) posses all four structures the classify chordates, however adult tunicates retain only pharyngeal slits.Larval tunicates swim because that a few days ~ hatching, then attach to a marine surface and undergo metamorphosis right into the sessile adult form.Lancelets (Cephalochordata) are maritime organisms the possess all attributes of chordates; lock are named 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 in ~ the phylum Chordata: the tunicates or sea squirtsCephalochordata: a taxonomic subphylum within the phylum Chordata: the lanceletssessile: permanently attached come a substrate; not complimentary to move about; “an attached oyster”

Chordates and the development of Vertebrates

The most acquainted group that chordates is the vertebrates. However, in enhancement to the subphylum Vertebrata, the phylum Chordata also contains 2 subphylums that invertebrates: Urochordata and also Cephalochordata. Members of this groups additionally possess the four distinctive features of chordates at some allude during their development: a notochord, a dorsal hole nerve cord, pharyngeal slits, and also a post-anal tail. Uneven vertebrates, urochordates and cephalochordates never construct a bony backbone.


Members the Urochordata are also known as tunicates. The name tunicate derives from the cellulose-like carbohydrate material, called the tunic, i beg your pardon covers the outer body of tunicates. Return tunicates are classified as chordates, only the larval type possesses all four common structures. Adults only preserve pharyngeal slits and lack a notochord, a dorsal hollow nerve cord, and also 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 attributes characteristic that chordates: a notochord, a dorsal hole 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 room hermaphrodites. Tunicate larvae flower from eggs inside the adult tunicate’s body. After hatching, a tunicate larva swims for a couple of days till it finds a perfect surface on i beg your pardon it can attach, typically 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 suggest the notochord, nerve cord, and also tail disappear.

Most tunicates live a sessile visibility on the ocean floor and also are suspension feeders. The primary foods of tunicates space plankton and also detritus. Seawater start the tunicate’s body with its incurrent siphon. Suspended material is filtered the end of this water through a mucous net (pharyngeal slits) and is passed into the intestine via the action of cilia. The anus empties right into the excurrent siphon, which expulsion wastes and water. Tunicates are found in shallow s waters approximately the world.


Members of Cephalochordata possess 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, however the notochord extends right into the head, which gives the subphylum its surname ( “cephalo” is Greek because that head). Die out members of this subphylum incorporate Pikaia, i beg your pardon is the oldest known cephalochordate. Pikaia fossils were recovered indigenous the burgess shales of Canada and also dated to the middle of the Cambrian age, making them much more than 500 million year old.

Extant members of Cephalochordata are the lancelets, called for your blade-like shape. Lancelets are only a few centimeters long and also are commonly found hidden in sand in ~ the bottom of heat temperate and also tropical seas. Prefer tunicates, they are suspension feeders. Through notochord and paired muscle blocks, the lancelet and also Pikaia might belong come the chordate team of pets from i m sorry the vertebrates have actually descended.

Cephalochrodates: The lancelet, prefer all cephalochordates, has a head. Adult lancelets retain the four key features of chordates: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail. Water indigenous the mouth beginning the pharyngeal slits, i m sorry filter the end food particles. The filtered water then collects in the atrium and exits through the atriopore.

Key Takeaways

Key PointsThe clade Craniata includes animals that have actually a cranium: a bony, cartilaginous, or fibrous framework that surrounding the brain, jaw, and facial bones.Members the Craniata encompass the vertebrates and also hagfish.Genomic evidence suggests that vertebrates sail from cephalochordates (lancelets), which had previously sail from urochordates (tunicates).Fossil evidence says that many vertebrate diversity source in the Cambrian explosion 540 million years ago.Two whole- genome duplications developed in early on vertebrate history.Key Termscranium: the component of the skull enclosing the brain, the braincasegenomics: the study of the finish genome of one organismCambrian explosion: the relatively rapid figure (over a period of countless millions of years), approximately 530 million year ago, that most major 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, which is a bony, cartilaginous, or fibrous structure neighboring the brain, jaw, and also facial bones. The clade Craniata includes all vertebrates and also the hagfishes (Myxini), which have a cranium but lack a backbone. Hagfish are the only well-known living animals that have actually a skull, yet not a vertebral column.


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

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

Vertebrates: Vertebrata are defined by the presence of a backbone, such together the one the runs with the center of this fish. Every vertebrates space in the Craniata clade and also 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 invertebrate genomes (genomics), scientists can determine the evolutionary history of various phylogenetic groups.

According to this genomic analyses, vertebrates show up to be an ext closely concerned the lancelets (cephalochordates) than to the tunicates (urochordates). This argues that the cephalochordates very first diverged native urochordates, and also that vertebrates consequently diverged indigenous the cephalochordates. This theory is more supported by the fossil of a 530 million-year-old organism through a brain and eyes like a vertebrate, yet without the skull found in a craniate. A to compare of the genomes the a lancelet, tunicate, lamprey, fish, chicken, and human shown that 2 whole-genome duplications developed in the early background of the Vertebrata subphylum.

Both fossil and also genomic evidence says that vertebrates emerged during the Cambrian explosion.The Cambrian explosion was the relatively brief expectancy of time during the Cambrian duration during i m sorry many animal groups appeared and also rapidly diversified. Most modern-day animal phyla originated throughout the Cambrian explosion.

Characteristics that Vertebrates

Vertebrata is a subphlyum that Chordata that is further identified by your bony backbone.

Key Takeaways

Key PointsAs chordates, vertebrates have actually the same common features: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail.Vertebrates space further identified from chordates by your vertebral column, which creates when their notochord develops into the shaft of bony vertebrae be separated by discs.Vertebrates room the just chordates that have actually a brain as component of their central nervous system.Key Termsvertebral column: the series of vertebrae that safeguard the spinal cord; the spinal columnchordate: a member of the phylum Chordata; numerous animals having a notochord at some stage of their development; in vertebrates this develops into the spinenotochord: a flexible rodlike framework that forms the key support of the body in the shortest chordates; a primitive spine

Characteristics the Vertebrates

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

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

As chordates, every vertebrates have actually a comparable anatomy and morphology v the very same qualifying characteristics: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail. However, the subphylum Vertebrata is distinguished from the phylum Chordata by 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 also rays.

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

More than 64,000 species of vertebrates have been described, however the extant vertebrate species represent only a small part of every the vertebrates that have existed. Vertebrates variety in size from the frog species Paedophryne amauensis (as little as 7.7 mm (0.3 inch)) come the blue whale (as large as 33 m (110 ft)). Vertebrates comprise about 4 percent of every described animal species; the remainder are invertebrates, which absence backbones.

Anatomy and Morphology

All vertebrates are developed along the straightforward chordate human body plan: a stiff rod running v the length of the animal (vertebral column), v a hollow tube of nervous organization (the spinal cord) over it and also the gastrointestinal tract below. In all vertebrates, there is a mouth in ~ anterior finish of the animal and an anus prior to the posterior finish of the body. There is a tail posterior to the anus during at least one step of the animal’s development.

The Vertebral Column

Vertebrates are identified by the visibility of the vertebral column. In vertebrates, the notochord creates into the vertebral obelisk or spine: a series of bony vertebrae every separated through mobile discs. This vertebrae are always found ~ above the dorsal side of the animal. However, a few vertebrates have actually secondarily shed their vertebrae and, instead, retain the notochord right into adulthood (e.g., the sturgeon fish).


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

Central concerned System

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

Vertebrate Classification

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

See more: How Many Cm Are In A Mile S To Cm, Convert Mile To Centimeter

Animals that possess jaws are known as gnathostomes, definition “jawed mouth.” Gnathostomes include fishes and also tetrapods (amphibians, reptiles, birds, and mammals). Tetrapods can be further separated into two groups: amphibians and also amniotes. Amniotes are pets whose egg are adapted for terrestrial living; this group has mammals, reptiles, and also birds. Amniotic embryos, arising in one of two people an externally-shelled egg or an egg carried by the female, are detailed with a water-retaining environment and also are safeguarded by amniotic membranes.