Characteristics of Chordata

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

You are watching: To be characterized as a chordate, an organism must

Key Takeaways

Key PointsThese attributes are only present during embryonic advance in some chordates.The notochord gives skeletal support, provides the phylum the name, and also develops into the vertebral pillar in vertebrates.The dorsal hole nerve cord develops into the central nervous system: the brain and spine.Pharyngeal slits space openings in the pharynx that build into gill arcs in bony fish and also into the jaw and inner ear in terrestrial animals.The post-anal tail is a skeletal expansion of the posterior finish of the body, being missing in humans and also apes, although current during embryonic development.Key Termsnotochord: a versatile rodlike structure that develops the key support of the human body in the lowest chordates; a primitive spinenerve cord: a dorsal tubular cord of concerned tissue above the notochord that a chordatepharyngeal slit: filter-feeding organs discovered in non-vertebrate chordates (lancelets and also tunicates) and hemichordates life in aquatic environments

Characteristics the Chordata

Animals in the phylum Chordata re-publishing four an essential features that appear at part stage throughout their advancement (often, only throughout embryogenesis) (:

Defining attributes of chordates: In chordates, four common 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 hollow nerve cordpharyngeal slitspost-anal tail


The chordates are called 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 some chordate species. It 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 as the main axial support of the human body throughout the animal’s lifetime.

In vertebrates, the notochord is present during embryonic development, in ~ which time the induces the advancement of the neural pipe which serves together a assistance for the emerging embryonic body. The notochord, however, is changed by the vertebral tower (spine) in many adult vertebrates.

Dorsal hollow Nerve Cord

The dorsal hollow nerve cord derives indigenous ectoderm that rolls right into a hollow tube during development. In chordates, it is situated dorsally (at the optimal of the animal) to the notochord. In contrast to the chordates, other animal phyla are defined by heavy nerve cords that are situated either ventrally or laterally. The nerve cord discovered in most chordate embryos develops into the mind and spinal cord, which comprise the central nervous system.

Pharyngeal Slits

Pharyngeal slits room openings in the pharynx (the region just posterior come the mouth) that extend to the outside environment. In organisms that live in aquatic environments, pharyngeal slits permit for the departure of water that 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 most terrestrial animals, including mammals and birds, pharyngeal slits are present only during embryonic development. In this animals, the pharyngeal slits develop into the jaw and also inner ear bones.

Post-anal Tail

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

Chordates and the advancement of Vertebrates

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

Key Takeaways

Key PointsUrochordata (tunicates) and also Cephalochordata (lancelets) space invertebrates because they lack a backone.Larval tunicates (Urochordata) posses all four structures that classify chordates, yet adult tunicates retain just pharyngeal slits.Larval tunicates swim because that a couple of days after ~ hatching, then attach to a maritime surface and undergo metamorphosis into the sessile adult form.Lancelets (Cephalochordata) are naval organisms that possess all features of chordates; lock are named Cephalochordata because the notochord extends into the head.Lancelets might be the closest-living loved ones to vertebrates.Key TermsUrochordata: a taxonomic subphylum in ~ the phylum Chordata: the tunicates or sea squirtsCephalochordata: a taxonomic subphylum in ~ the phylum Chordata: the lanceletssessile: permanently attached to a substrate; not totally free to move about; “an fastened oyster”

Chordates and the development of Vertebrates

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


Members of Urochordata are also known together tunicates. The name tunicate derives from the cellulose-like carbohydrate material, referred to as the tunic, i beg your pardon covers the external body that tunicates. Return tunicates room classified together chordates, just the larval form possesses all four common structures. Adults only preserve pharyngeal slits and also lack a notochord, a dorsal hollow 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 every one of the attributes characteristic of 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 hatch from eggs inside the adult tunicate’s body. After ~ hatching, a tunicate larva swims because that a few days till it finds a suitable surface on i m sorry it can attach, usually in a dark or shaded location. It climate attaches via the head come 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 existence on the ocean floor and also are suspension feeders. The primary foods items of tunicates space plankton and also detritus. Seawater beginning the tunicate’s body with its incurrent siphon. Suspended product is filtered the end of this water by a mucous network (pharyngeal slits) and also is passed right into the intestine via the activity of cilia. The anus empties right into the excurrent siphon, which expulsion wastes and water. Tunicates are found in shallow s waters about the world.


Members of Cephalochordata own a notochord, dorsal hole nerve cord, pharyngeal slits, and a post-anal tail in the adult stage. They carry out not have a true brain, however the notochord extends right into the head, which provides the subphylum its surname ( “cephalo” is Greek for head). Extinct members the this subphylum incorporate Pikaia, i beg your pardon is the oldest recognized cephalochordate. Pikaia fossils to be recovered indigenous the citizen shales of Canada and also dated come the middle of the Cambrian age, make them an ext than 500 million years old.

Extant members the Cephalochordata room the lancelets, named for your blade-like shape. Lancelets are just a couple of centimeters long and are typically found hidden in sand at the bottom of warm temperate and tropical seas. Like tunicates, they are suspension feeders. Through notochord and also paired muscle blocks, the lancelet and Pikaia may belong to the chordate team of pets from i beg your pardon the vertebrates have descended.

Cephalochrodates: The lancelet, choose all cephalochordates, has a head. Adult lancelets retain the four crucial features of chordates: a notochord, a dorsal hole nerve cord, pharyngeal slits, and a post-anal tail. Water from the mouth beginning the pharyngeal slits, i m sorry filter the end food particles. The filtered water then collects in the atrium and exits with 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 also facial bones.Members of Craniata encompass the vertebrates and also hagfish.Genomic evidence argues that vertebrates diverged from cephalochordates (lancelets), which had previously sail from urochordates (tunicates).Fossil evidence argues that many vertebrate diversity source in the Cambrian to explode 540 million years ago.Two whole- genome duplications occurred in at an early stage vertebrate history.Key Termscranium: the part of the skull enclosing the brain, the braincasegenomics: the examine of the finish genome of one organismCambrian explosion: the fairly rapid figure (over a period of many millions that years), around 530 million years ago, of most major animal phyla as demonstrated in the fossil record

Craniata and also Vertebrata

The clade Craniata is a subdivision of Chordata. Members of Craniata posses a cranium, i beg your pardon is a bony, cartilaginous, or fibrous structure bordering the brain, jaw, and also facial bones. The clade Craniata has all vertebrates and also the hagfishes (Myxini), which have actually a cranium yet lack a backbone. Hagfish are the only recognized living pets that have a skull, yet not a vertebral column.


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

Vertebrates: Vertebrata are defined by the visibility of a backbone, such as the one that runs with the center of this fish. All vertebrates are in the Craniata clade and also have a cranium.

Vertebrate Evolution

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

According to these genomic analyses, vertebrates show up to be much more closely concerned the lancelets (cephalochordates) than to the tunicates (urochordates). This suggests that the cephalochordates an initial diverged native urochordates, and that vertebrates consequently diverged native the cephalochordates. This theory is further supported by the fossil that a 530 million-year-old organism with a mind and eyes choose 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 shown that two whole-genome duplications developed in the early history of the Vertebrata subphylum.

Both fossil and genomic evidence says that vertebrates arose during the Cambrian explosion.The Cambrian explosion to be the relatively brief expectancy of time during the Cambrian duration during which many pet groups appeared and also rapidly diversified. Most contemporary animal phyla originated during the Cambrian explosion.

Characteristics of Vertebrates

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

Key Takeaways

Key PointsAs chordates, vertebrates have the same typical features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.Vertebrates are further identified from chordates by your vertebral column, which creates when your notochord creates into the obelisk of bony vertebrae separated by discs.Vertebrates space the only chordates that have a brain as part 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 in ~ some stage of their development; in vertebrates this establishes into the spinenotochord: a functional rodlike structure that forms the key support the the human body in the shortest chordates; a primitive spine

Characteristics of Vertebrates

Vertebrates are members the the subphylum Vertebrata, under the phylum Chordata and under the kingdom Animalia. Pets that possess bilateral symmetry deserve to be separated into two groups, protostomes and also deuterostomes, based upon their fads of embryonic development. The deuterostomes, who name equates as “second mouth,” consist of two phyla: Chordata and also Echinodermata. Echinoderms room invertebrate marine pets that have pentaradial symmetry and a spiny body covering; the phylum includes sea stars, sea urchins, and sea cucumbers. The phylum Chordata consists of two teams of invertebrate chordates, however the many conspicuous and familiar members that Chordata are the vertebrates.

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

As chordates, all vertebrates have a comparable anatomy and morphology v 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 differentiated from the phylum Chordata by the advancement of the notochord into a bony backbone. Vertebrates incorporate the amphibians, reptiles, mammals, and birds, and also the jawless fishes, bony fishes, sharks, and also rays.

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

More 보다 64,000 species of vertebrates have actually been described, but the extant vertebrate varieties represent only a small part of all the vertebrates that have actually existed. Vertebrates selection in size from the frog types Paedophryne amauensis (as small 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 are invertebrates, which lack backbones.

Anatomy and also Morphology

All vertebrates are constructed along the an easy chordate human body plan: a stubborn rod running v the size of the pet (vertebral column), through a hole tube of nervous organization (the spinal cord) above it and the gastrointestinal street below. In all vertebrates, over there is a mouth in ~ anterior end of the animal and an anus before the posterior finish of the body. Over 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 presence of the vertebral column. In vertebrates, the notochord establishes into the vertebral shaft or spine: a series of bony vertebrae each separated through mobile discs. This vertebrae are constantly found on the dorsal next of the animal. However, a few vertebrates have secondarily shed their vertebrae and, instead, maintain the notochord right into adulthood (e.g., the sturgeon fish).


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

Central nervous System

Vertebrates are likewise the only members of Chordata to own a brain. In chordates, the central nervous mechanism is based upon a hole nerve tube that runs dorsal come the notochord along the size of the animal. In vertebrates, the anterior finish of the nerve pipe expands and also differentiates right into three brain vesicles.

Vertebrate Classification

Vertebrates space the largest group of chordates, with an ext than 62,000 living species. Vertebrates room grouped based upon anatomical and physiological traits. The classic groups include Agnatha, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and also Mammalia.

See more: Option Credit Spreads Destroyed My Life : This Is Why, Weekly Options Credit Spread Horror Story

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