Characteristics that Chordata

Animals in the phylum Chordata share four an essential 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 present during embryonic advance in some chordates.The notochord gives skeletal support, gives the phylum that is name, and also develops into the vertebral obelisk 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 construct into gill arches in bony fish and into the jaw and inner ear in terrestrial animals.The post-anal tail is a skeletal expansion of the posterior end of the body, being absent in humans and apes, although existing during embryonic development.Key Termsnotochord: a functional 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 that a chordatepharyngeal slit: filter-feeding organs uncovered in non-vertebrate chordates (lancelets and tunicates) and hemichordates living in aquatic environments

Characteristics the Chordata

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

Defining qualities of chordates: In chordates, four usual features appear at some suggest 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 chordates are named for the notochord: a flexible, rod-shaped framework that is found in the embryonic stage of every chordates and also in the adult phase of part chordate species. It is located in between the digestive tube and also the nerve cord, providing skeletal assistance through the size of the body. In some chordates, the notochord acts as the primary axial assistance of the human body throughout the animal’s lifetime.

In vertebrates, the notochord is present during embryonic development, in ~ which time it induces the advancement of the neural tube which serves as a assistance for the occurring embryonic body. The notochord, however, is replaced by the vertebral shaft (spine) in many adult vertebrates.

Dorsal hole Nerve Cord

The dorsal hole nerve cord derives from ectoderm the rolls right into a hole tube throughout development. In chordates, it is situated dorsally (at the peak of the animal) come the notochord. In contrast to the chordates, other animal phyla are characterized by hard nerve cords the are situated either ventrally or laterally. The nerve cord uncovered in many chordate embryos creates into the mind and spinal cord, which make up the main nervous system.

Pharyngeal Slits

Pharyngeal slits room openings in the pharynx (the an ar just posterior to the mouth) that extend to the exterior environment. In organisms that live in aquatic environments, pharyngeal slits permit for the exit of water the 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 build into gill arches, the bony or cartilaginous gill supports.

In many terrestrial animals, including mammals and birds, pharyngeal slits are existing only during embryonic development. In these animals, the pharyngeal slits develop into the jaw and also inner ear bones.

Post-anal Tail

The post-anal tail is a posterior elongation of the body, extending past the anus. The tail contains skeletal elements and also muscles, which administer a resource of locomotion in aquatic species. In part terrestrial vertebrates, the tail likewise helps v balance, courting, and signaling once danger is near. In humans and also other apes, the post-anal tail is current during embryonic development, however is vestigial as an adult.

Chordates and the evolution of Vertebrates

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

Key Takeaways

Key PointsUrochordata (tunicates) and also Cephalochordata (lancelets) room invertebrates because they absence a backone.Larval tunicates (Urochordata) posses all four structures that classify chordates, however adult tunicates retain just pharyngeal slits.Larval tunicates swim because that a few days ~ hatching, then connect to a maritime surface and undergo metamorphosis right into the sessile adult form.Lancelets (Cephalochordata) are marine organisms the possess all functions of chordates; castle are named Cephalochordata due to the fact that the notochord extends into the head.Lancelets might be the closest-living loved ones 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 free to move about; “an fastened oyster”

Chordates and the advancement 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 additionally possess the 4 distinctive features of chordates in ~ some allude during their development: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail. Unequal vertebrates, urochordates and also cephalochordates never develop a bony backbone.


Members the Urochordata are also known together tunicates. The surname tunicate derives from the cellulose-like carbohydrate material, dubbed the tunic, i m sorry covers the outer body that tunicates. Although tunicates are classified as chordates, just the larval type possesses all four typical structures. Adults only keep pharyngeal slits and also lack a notochord, a dorsal hole nerve cord, and a post-anal tail.

Urochordates: (a) This picture shows a swarm of the tunicate Botrylloides violaceus. (b) The larval stage of the tunicate possesses all of the features characteristic the 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 tail disappear.

Most tunicates room hermaphrodites. Tunicate larvae hatch from eggs inside the adult tunicate’s body. After hatching, a tunicate larva swims because that a couple of days until it finds a an ideal surface on i m sorry it deserve to attach, commonly in a dark or shaded location. It climate attaches via the head to the surface and undergoes metamorphosis right into the adult form, in ~ 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 foodstuffs of tunicates are plankton and also detritus. Seawater start the tunicate’s body v its incurrent siphon. Suspended product is filtered out of this water by a mucous network (pharyngeal slits) and also is passed into the intestine via the activity of cilia. The anus empties right into the excurrent siphon, which expels wastes and also water. Tunicates are found in shallow ocean waters around the world.


Members the Cephalochordata own a notochord, dorsal hole nerve cord, pharyngeal slits, and also a post-anal tail in the adult stage. They execute not have a true brain, however the notochord extends right into the head, which offers the subphylum its name ( “cephalo” is Greek because that head). Extinction members that this subphylum incorporate Pikaia, i m sorry is the oldest known cephalochordate. Pikaia fossils to be recovered from the citizen shales of Canada and also dated to the center of the Cambrian age, making them more than 500 million years old.

Extant members of Cephalochordata are the lancelets, named for your blade-like shape. Lancelets are only a few centimeters long and are normally found hidden in sand in ~ the bottom of warm temperate and also tropical seas. Favor tunicates, they are suspension feeders. With notochord and paired muscle blocks, the lancelet and also Pikaia might belong come the chordate group of animals from i beg your pardon the vertebrates have actually descended.

Cephalochrodates: The lancelet, favor all cephalochordates, has a head. Adult lancelets retain the four vital features of chordates: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail. Water from the mouth enters the pharyngeal slits, i beg your pardon 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 a cranium: a bony, cartilaginous, or fibrous framework that surrounding the brain, jaw, and facial bones.Members the Craniata incorporate the vertebrates and hagfish.Genomic evidence says that vertebrates diverged from cephalochordates (lancelets), which had actually previously diverged from urochordates (tunicates).Fossil evidence suggests that most vertebrate diversity originated in the Cambrian to explode 540 million years ago.Two whole- genome duplications arisen in at an early stage vertebrate history.Key Termscranium: the part of the skull enclosing the brain, the braincasegenomics: the research of the finish genome of an organismCambrian explosion: the relatively rapid appearance (over a period of countless millions the years), around 530 million year ago, the most major animal phyla together demonstrated in the fossil record

Craniata and Vertebrata

The clade Craniata is a subdivision that Chordata. Members that Craniata posses a cranium, which is a bony, cartilaginous, or fibrous structure surrounding the brain, jaw, and facial bones. The clade Craniata has all vertebrates and the hagfishes (Myxini), which have actually a cranium yet lack a backbone. Hagfish room the only known living pets that have a skull, however not a vertebral column.


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

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

Vertebrates: Vertebrata are identified by the visibility of a backbone, such as the one the 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 family members 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 history of different phylogenetic groups.

According to these genomic analyses, vertebrates show up to be more closely concerned the lancelets (cephalochordates) 보다 to the tunicates (urochordates). This argues that the cephalochordates very first diverged indigenous urochordates, and that vertebrates consequently diverged indigenous the cephalochordates. This theory is additional supported through the fossil that a 530 million-year-old organism through a mind and eyes favor a vertebrate, however without the skull uncovered in a craniate. A to compare of the genomes of a lancelet, tunicate, lamprey, fish, chicken, and also human evidenced that two whole-genome duplications developed in the early history of the Vertebrata subphylum.

Both fossil and genomic evidence says that vertebrates developed during the Cambrian explosion.The Cambrian explosion was the relatively brief span of time during the Cambrian period during i m sorry many animal groups appeared and also rapidly diversified. Most contemporary animal phyla originated throughout the Cambrian explosion.

Characteristics that 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 common features: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail.Vertebrates are further differentiated from chordates by your vertebral column, which develops when your notochord develops into the pillar 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 protect the spinal cord; the spinal columnchordate: a member of the phylum Chordata; numerous animals having a notochord in ~ some phase of your development; in vertebrates this establishes into the spinenotochord: a flexible rodlike framework that forms the main support that the human body in the shortest chordates; a primitive spine

Characteristics of Vertebrates

Vertebrates space members of the subphylum Vertebrata, under the phylum Chordata and also under the kingdom Animalia. Animals that own bilateral symmetry can be separated into two groups, protostomes and deuterostomes, based upon their trends of embryonic development. The deuterostomes, whose name converts as “second mouth,” consist of of 2 phyla: Chordata and also Echinodermata. Echinoderms are invertebrate marine pets that have pentaradial symmetry and a spiny body covering; the phylum contains sea stars, sea urchins, and sea cucumbers. The phylum Chordata consists of two teams of invertebrate chordates, however the most conspicuous and familiar members the Chordata are the vertebrates.

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

As chordates, all vertebrates have a comparable anatomy and 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 into a bony backbone. Vertebrates incorporate the amphibians, reptiles, mammals, and also birds, and also the jawless fishes, bony fishes, sharks, and rays.

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

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

Anatomy and also Morphology

All vertebrates are constructed along the an easy chordate body plan: a stiff rod running through the size of the pet (vertebral column), with a hollow tube of nervous tissue (the spinal cord) above it and also the gastrointestinal street below. In all vertebrates, there is a mouth in ~ anterior end of the animal and also an anus prior to the posterior end 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 characterized by the existence of the vertebral column. In vertebrates, the notochord creates into the vertebral obelisk or spine: a collection of bony vertebrae every separated through mobile discs. These vertebrae are constantly found on the dorsal side of the animal. However, a few vertebrates have actually 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 the the backbone that characterizes vertebrates.

Central nervous System

Vertebrates are additionally the just members of Chordata to own a brain. In chordates, the main nervous system is based on a hollow nerve tube the runs dorsal to the notochord along the length of the animal. In vertebrates, the anterior finish of the nerve tube expands and differentiates right into three brain vesicles.

Vertebrate Classification

Vertebrates are the largest team of chordates, with an ext than 62,000 life species. Vertebrates room grouped based on anatomical and physiological traits. The timeless groups incorporate 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 encompass fishes and also tetrapods (amphibians, reptiles, birds, and mammals). Tetrapods deserve to be further divided into 2 groups: amphibians and also amniotes. Amniotes are animals whose egg are adjusted for terrestrial living; this group consists of mammals, reptiles, and also 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 are defended by amniotic membranes.