Phylum Chordata Characteristics and Examples

  • Hamza Ali


The subject matter chosen for this biological study was the Kingdom Animalia. This study will specifically be examining the Phylum Chordata, by giving an benefits to Chordates, Vertebrates, The Classification method of Cladistics, Seafood, Amphibian, and Reptiles.

What are vertebrates?

Vertebrates are known as pets or animals that have an interior spine made of bone. Vertebrates include reptiles, amphibians, seafood, birds, mammals, primates, rodents and marsupials (Kidport, 2012).

There are about 57, 000 types of vertebrates alive today, which only speaks for about 3% of varieties alive today. The other 97% of species alive today, are invertebrates. Vertebrates have a vertebral column in which the notochord is substituted by multiple vertebrae that form a backbone. The vertebrae also protect and encircle a nerve cord which gives the animal structural support.

  • Structural details:

Vertebrates have a well-formed brain, a distinct brain protected by the skull, aswell as sense organs. They also have a highly efficient respiratory system, a muscular pharynx with slits and gills (in terrestrial vertebrates the slits and gills are greatly changed), a burly gut, and a chambered heart. Another notable characteristic that vertebrates have is their endoskeleton! An endoskeleton is an inner assemblage of notochord, bone or cartilage that provides the pet with structural support. The endoskeleton increases as the animal grows and provides a sturdy framework to which the animal's muscles are fastened.

What are Chordates?

Chordates are known as all animals in the phylum Chordata. A phylum is second most standard taxon. The Chordata is the animal phylum that everyone is probably familiar with, as it offers humans and othervertebrates. However, not all chordates are vertebrates! Chordates consist of three subphylums or categories, called vertebrates, tunicates, and lancelets. All chordates are similar as they are known to have got the following features sooner or later in their life (humans and a great many other vertebrates only have got some of these features in the embryo) (University of California Berkelely, n. d. ).

General structure:

Figure 1. Features of a Chordate

Pharyngeal slits- some openings that hook up the within of the throat to the outside of the "neck". These are often, but not always, used as gills.

Dorsal nerve cord- a bundle of nerve fibres which run down the "returning" and connects the brain to organs and lateral muscles.

The Notochord- is a cartilaginous rod ( a pole made out of cartilage which is a type of delicate bone ) working underneath, and promoting, the nerve wire.

The Post-anal tail- an extension of the body past the anal opening ( such as a tail )(University of California Berkelely, n. d. ).

Chordates come in a large amount sizes and shapes due to the large variety of pets that are covered in this phylum. Chordates are regarded as as big as whales and elephants, to as small as little sea squirts!

  • Taxonomy of Chordates:

Chordates can be split into three subphylums which help us determine the distinctions between other Chordates.

The first subphylum isSubphylum Vertebrata(vertebrates). "They may attended from anAmphioxus-like ancestor, however vertebrates have a definite brain andAmphioxusdoesn't. Another theory shows that vertebrates may have come from a larval form comparable to tunicate larvae that were capable of reproduction in the larval level, that is, they are simply sexually older prior to metamorphosis, which is referred to aspaedogenesis(paedo= child - same root just as pediatrician;genesis= origin, birth), thought as the precocious attainment of erotic maturity in a larva"(Carter, 2014).

Another subphylum which are play a big role as Chordates are lancelets. Lancelets (cephalochordata) aresmall and long sea invertebrates that resemble seafood but do not have got jaws and obvious sense organs. Lancelets do have a notochord and are among the most primitive chordates. As lancelets are invertebrates they do not have got a spine!In most vertebrates, the embryonic notochord is eventually replaced by bony vertebrae or cartilaginous muscle yet with cephalochordates, the notochord is maintained into adulthood and is also never substituted by vertebrae. There are around 20 species in two individuals, each with an individual genus. Branchiostomawas previously calledAmphioxus, a name that is held as a casual term. The other genus isEpigonichthys, is also calledAsymmetron. The genusAsymmetronis sometimes retained for some kinds. The cephalochordate fossil record dates back to about 525 million years back during the early Cambrian Period (Ghiselin, 2015).

And the 3rd subphylum of the phylum Chordata is Urochordata also known as Tunicates. Tunicates are small sea animals that are found in great quantities. According to analyze most chordate top features of tunicates disappear during metamorphosis. A few examples of tunicates are sea squirts (Ghiselin, 2015).

What is the value of Chordates in an ecosystem?

Chordates are mainly essential for an ecosystem as these vertebrates or invertebrates will be the carnivores or herbivores or omnivores which help support said ecosystem. The phylum Chordata consists of many pets or animals which consume and hunt down other pets, hence keeping the numbers of predator and victim. Omnivores also help an ecosystem preserve itself as a lot more they eat crops a lot more room you will see for other plants to expand. Chordates also help the surroundings as their excretion, bones, and remains provide nutrition and mineral deposits to ecosystem. All in all, Chordates are detrimentally important to ecosystems, as their actions have an effect on the ecosystems sustainability in an exceedingly large method.

What are cladistics?

According to analyze; "Cladistics is a particular method of hypothesizing connections among organisms. Like other methods, they have its own set of assumptions, methods, and constraints. Cladistics is currently accepted as the most practical method designed for phylogenetic analysis, for this provides an explicit and testable hypothesis of organismal associations" (University of California Berkelely, n. d. ).

The basic idea of cladistics is that members of an organization derive from a common evolutionary history and for that reason, are more carefully related to members of that same group than to other organisms. These groupings are acknowledged by posting unique features that have been not within faraway ancestors. Theseshared an derivedcharacteristics are calledSynapomorphies (College or university of California Berkelely, n. d. ).

  • What assumptions do Cladists make?

There are some common assumptions that are made in cladistics:

  1. Any band of organisms arerelated by descentfrom a typical ancestor.
  2. There is abifurcating patternof cladogenesis.
  3. Changein characteristics occurs in lineages over time(School of California Berkelely, n. d. ).

Cladistics General Structure:

Figure 2. A good example of a basic Caladogram,

In this example of a cladistic, 5 family pets are compared, and their similarities suggest that some animals are more carefully related to others, like the lizard and the hen, versus the chipmunk and the frog.

  • Types of features:

- Apomorphic, or derived features are features that originate within different associates of the group, and therefore differentiate them. Apomorphic features are extremely useful in cladistic classification as they help us see distinctions between organisms.

- Plesiomorphic features are primitive features that are shared with all associates of the group. Plesiomorphic features are not useful in Cladistics.

In brief, Cladisticsare a method of classifying plant life and animals according to the percentage of common characteristics they share. It is clear that the higher the proportion of common characteristics, the recently the organisms diverged from the ancestor!


Fish are the most numerous and wide-spread of all the vertebrates as there are so many fish species! In short, there are three categories of fish; Jawless seafood, bony fish, and cartilaginous seafood. All fish have got hills and live under water. Of the 22000 varieties of seafood, it is well known that 40% reside in fresh drinking water and 60% live in salt water.

What are Jawless fish?

Jawless seafood are also known as category Agatha. Jawless fish are protected with slimy skin area and don't have combined fins. They have smooth eel like systems and possess a notochord. Jawless fish are made up of cartilage rather than bone. School agatha comprises of 70 kinds of lampreys and hag fish. Lampreys are small seafood that have a big sucker with many tiny teeth. They are simply most known for the damage they cause in the Great Lakes. Hagfish are scavengers that eat useless or dying seafood, and are more like scavengers who stay at the bottom of the ocean. They have a mouth surrounded by tentacles or "feelers", but likewise have a row of 'toothlike' pearly whites which help them devour their prey.

What are Bony Fish?

Bony fish are also called class Osteichthyes. Bony fish will be the most numerous of all vertebrates; they include salmon, trout, cod, eel, halibut and so many more. All living types of bony seafood can be split into three subclasses; Ray finned seafood, primitive seafood, and lung seafood. Ray finned fish are your average seafood, they have a set body with covered with flexible scales. And their fertilization is usually external. Primitive seafood such as sharks must keep swimming constantly by they don't they will sink. This is because sharks don't have a swim bladder.

What are Cartilaginous seafood?

Lastly, cartilaginous fish ( class Chondrichthyes ) involves sharks, skates and Ray fish which have a cartilaginous body. Cartilage is a very soft type of bone. Cartilaginous seafood have two major advantages over jawless fish, matched fins and biting jaws! The very best known cartilaginous seafood are the sharks! The major sharks including the whale shark, prey on plankton in the sea, but most sharks prey on other fish, bottom dwellers, molluscs and lobsters. Skates and rays are very just like sharks but have a flat streamline body. This is because their systems have modified to living on underneath of the sea.

Amphibians versus Reptiles:

Amphibians are cold-blooded vertebrate pets of a school that comprises offrogs, toads, newts, and salamanders. They are different by having an aquatic gill-breathing stage followed (typically) by the terrestrial lung-breathing stage in adulthood (Zug, 2014) Amphibians live on land and drinking water.

According to analyze more than 6, 500 kinds of living amphibians are known. They first appeared about 340 million years back during the Middle Mississippian Epoch, plus they were one of the initial groupings to diverge from ancestral fish-tetrapod stock through the evolution of pets from totally aquatic varieties to terrestrial types. Recently, amphibians are symbolized bytoads, frogs, (order Anura), newts and salamanders (order Caudata), and caecilians (order Gymnophiona). As an organization, the three purchases create the subclass called Lissamphibia. Neither the lissamphibians nor the extinct sets of amphibians are the ancestors of the band of tetrapods that gave rise toreptiles. While some areas of the anatomy and biology of varied amphibian organizations might seem closely related to reptilian ancestors, amphibians are not the intermediate part of the advancement of reptiles from fishes (Zug, 2014).

Furthermore, Encyclopedia Brittanica claims that; "modern amphibians are united by several unique features. They typically have a moist epidermis and rely heavily on cutaneous (skin-surface)respiration. They have got a double-channeled reading system, greenrodsin their retinas to discriminate hues, and pedicellate (two-part) teeth. A few of these traits may also have existed in extinct groupings" (Zug, 2014. Para 1).


Reptilesare cold-blooded vertebrates of your class that includes lizards, snakes, crocodiles, tortoises and turtles. They may be distinguished with a dry scaly pores and skin, and typically lay down smooth shell eggs on land.

Reptiles came out about 310 years ago and they are the first vertebrates to be totally terrestrial! You will discover roughly 7 thousand types of living reptiles on the planet. The class reptilia can be classified into three subclasses;

  1. Anapsida (turtles and tortoises)
  2. Lepidosaura (lizards snakes and the tuatara)
  3. Archosaura ( crocodiles, alligators and dinosaurs)

Furthermore, according to analyze: "The first reptile is thought to be the Hylonomus ("forest mouse"), which lived 315 million years back in what's now eastern Canada. It had been small pet, about 8 to 12 inches (20 to 30 cm) in length, and it ate insects. Around 230 million years back, during the Triassic period, new, much larger pets or animals - the first dinosaurs - improved, and these would continue to dominate terrestrial ecosystems for 160 million years, until these were wiped out during the Cretaceous-Tertiary extinction event 65 million years back. For their dominance during this time period, the Mesozoic Time is often called age Reptiles" (What are Reptiles, 2015).

Why and exactly how did reptiles progress?

Figure 3. This is one of the first reptiles

Hylonomus-Reptiles first come fromamphibiansin the swamps of the lateCarboniferous. Increasing evolutionary pressure of the land forced the evolutionary changes in amphibians to little by little become more land based. Because of the great quantity of available land and having less swamp area, small amphibians were compelled to move into terrestrial surroundings. Naturalselection projected the introduction of traits that have been necessary, like a stronger skeletal composition, muscles, and much more protecting covering such as scales. This is the fundamentals of the evolutionary motion for reptiles. And so reptiles like the first were created.

The progression of hip and legs and lungs were the main transitional steps towards reptiles, but the development ofthe smooth shelled eggs from the aquatic amphibian eggs was the true key switch point for reptiles as this allowed the animals to be completely recognized, and leave the aquatic environments. Another major difference from amphibians to reptiles is the increased brain size! Reptiles own an enlargedcerebrumandcerebellum. Although their brain size is small when compared to birds and mammals, these improvements prove vital in hunting approaches for reptiles. In addition, reptiles changed from amphibians and sauropsida as a result of environmental pressures that forced them to adapt to their new terrestrial environment (Pawley, 2006).

Importance of Amphibians to the Ecosystem:

Amphibians play an important ecological role as their life influences the ecosystem greatly. Because amphibians place their eggs in normal water, they are limited to stay in damp areas. Many amphibians, frogs specifically, help the ecosystem simply by breathing. This is because frogs breathing through their skin area, and can absorb many gases, this helps the environment a great deal. They also help sustain the environment by controlling place and canine levels in the ecosystem, as frogs and many amphibians ingest both canine and plant materials. Finally, over the years, many scientist have figured the degradation of an semi aquatic ecosystem has something regarding the degradation of amphibian populations in those ecosystems. Hence showing that amphibians do play an important ecological role in the sustenance of ecosystem.

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