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This blog will acknowledge the subphyla Vertebrata and its classes, namely Cyclostomata, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammals.

this image will provide the Roadmap For the Blog — **Roadmap For the Blog**

At a Glance

Before going to the main content, let’s summarize some basic facts about the Kingdom Animalia. As we know, the kingdom Animalia contains all the animals from the various phyla. The basic reason behind this study is to ware about our biological system and the huge biodiversity around us. This nomenclature system, different classifications, and separation according to their characteristics play a very important role in understanding natural evolution. All these things are not for the mug-up purpose. We should learn to apply this knowledge.

Previously we have seen classification of the Kingdom Animalia and its various phyla. Vertebrata is the Subphyla of the phylum Chordata. The unique characteristic about this phylum is the animals of this phyla possess a hollow, dorsal string-like structure known as the notochord. This phylum is subdivided into three subphyla, namely Urochordata or Tunicata, Cephalochordate, and Vertebrata. Among all three subphyla, Urochordata and cephalochordate are combinedly known as Protochordata. And these are exclusively marine individuals. Organ system level of organization is present in Protochordate. Protochordate doesn’t have a specific position in the biological nomenclature system.

this image will discuss about the outline of Division of Phylum Chordata — Division of Phylum Chordata

In Urochordates, the notochord is seen only in larval tails. While, in cephalochordates, the notochord is extended from head to tail area and remains throughout their life. Vertebrates are somehow different in possessing a notochord. Vertebrates show the presence of notochord during the embryonic period.

Subphyla Vertebrata

It is the major subphyla under the phylum Chordata which includes humans too. All the living individuals included in this subphylum are known as vertebrates. The name itself indicates the meaning of these individuals. The individuals with vertebral columns are termed vertebrates. The first tetrapod vertebrates, as well as the first vertebrates to live on land, are Amphibians. As the chordates, all vertebrates share some similar essential characteristics like having a hollow nerve cord, post-anal tail, and pharyngeal slits.

For more clearance, you can consider any living body with a particular skeletal structure that supports locomotion. This bony or skeletal structure holds as well as gives shape to the body.

This bony or skeletal structure is the replacement of notochord in the vertebrates. The vertebrates have a ventral muscular heart with two, three, or four chambers.

What you think, why can we dance, walk and sit?

The reason is due to the presence of vertebral columns and different bones. We can talk and can pronounce the right words just because of our fully developed jaws.

The presence of vertebral columns, jaws, mammary glands, etc., are some unique characteristics from which we can recognize vertebrates. These vertebrates are subdivided into five major classes: Pisces, Amphibia, Mammalia, Aves, and Reptilia.

This image describe the subphyla Vertebrata and its classes, namely Cyclostomata, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammals. — classes of subphyla vertebrata

These five classes are divided under two divisions, namely Agnatha, which means jawless organisms, and Gnathostomata means the organisms which bear jaw. It includes two superclasses, namely Cyclostomata, Pisces, and Tetrapoda.

Class of Subphylum Vertebrata: Cyclostomata

These are circular mouth-bearing organisms. It comes under the division agnatha, which contains living jawless fishes. Cyclostomates are the ectoparasites that are similar to succulents, living on the other fishes. Here you can imagine the mouth of “Mind Flayer,” the monster of stranger things seasons three without his giant spider hands. These sucking, circular and jawless organisms have elongated bodies up to six to fifteen pairs of gills slit for respiration. The cranium and vertebral columns present are cartilaginous.

Cyclostomates are marine but may migrate to the freshwater for spawning means to deposit their eggs, that is, babies. They die after few days of spawning, and the babies return to the ocean after metamorphosis. Hagfish, lamprey are some examples of Cyclostomata.

Super Class of Subphylum Vertebrata: Pisces

Pisces is the superclass that comes under the division Gnathostomata which bears true jaw. The significant characteristics of Pisces are the presence of an organ of respiration that is Gills and locomotion that is fins. Cold-blooded Pisces cannot regulate their body temperature and shows separate sexes with indirect and direct development.

Pisces is further classified into two classes, specifically Chondrichthyes and Osteichthyes.

Chondrichthyes

Class under Pisces which bears cartilaginous fishes. The mouth is ventrally present in this class of individuals. These organisms contain a gill slit without operculum, which is the cover of the gill. The teeth of Chondrichthyes are modified placoid scales. Just imagine the shark body mainly skin the spiny tooth-like structure present on sharks’ bodies known as placoid. This bony structure protects from predators and can injure prey. These organisms are primarily predacious.

If we don’t keep a floating belt during swimming, we will get sink-down, and hence we have to keep the body moving. Similarly, Chondrichthyes have to swim constantly to avoid sinking as they don’t have air bladder.

These fishes have two-chambered precisely one auricle and one ventricle heart. Some fishes’ possess’ electric organs like in torpedo, and some contain poison sting like in trigon. Many Chondrichthyans are viviparous and show internal fertilization.

Osteichthyes

They were exclusively named Bony Fish. They have skeletons primarily composed of bone tissue in contrast with the above fishes with skeletons composed of cartilage. The mouth position is terminal in Osteichthyes, with four pairs of gills covered by operculum on each side. Skin is covered with smooth-edged scales known as cycloids.

The presence of air bladder regulates the buoyancy in Osteichthyes. Have two-chambered heart, oviparous, and shows external fertilization.

Super Class of Subphylum Vertebrata: Tetrapoda

Name Tetrapoda indicates the meaning behind it, tetra, which means four, and poda means legs or limbs. The organism bearing four legs is exclusively distributed under superclass Tetrapoda. The first Tetrapod was aquatic. The change in their body structure from being aquatic to occupy Earth’s land is the most significant evolutionary change.

Early bony fishes that are Osteichthyes are the evolution point for Tetrapods. Having a pair of limbs, the ability to lay eggs, and feeding their offspring through mammary glands are unique characteristics that make this superclass different from others. This superclass includes four major classes, namely Amphibia, Reptilia, Aves, and Mammalia. Tetrapods can be oviparous, viviparous. And can show external and internal fertilization and indirect and direct development.

Amphibia

Amphibians are animals who live a double life as they can live in water and on land. The body of these animals is divided as head, trunk, and tail may present in some cases. Possess two pairs of limbs.

Amphibians can put on mascara as they have eyes with eyelids. On the other hand, they can’t wear earrings as they don’t have external ears. Instead of that, they have a tympanum that represents ears. Their food, baby, and urine travel through the common opening because their alimentary canal, urinary tract, and reproductive tract open into a common chamber called a cloaca. Amphibians can breathe through gills, lungs, and skin. Hence you can take special power yoga lessons from amphibians.

These are cold-blooded organisms with three-chambered hearts and present in separate sexes—for example, bufo (toad), frog, salamander, etc.

Reptilia

In Latin words, reptum means crawl; hence the reptilians are creeping and crawling organisms. These are mostly terrestrial animals having dry and cornified skin with epidermal scales. Reptiles heart is three as well as four-chambered in crocodiles, and they have two pairs of limbs. These are poikilothermic animals with separate sexes.

Reptilians, like snakes, lizards have the remarkable ability to shed their skin as cast. Some more examples are turtle, tortoise, cobra, etc.

Aves

This class might be every once favorite because it includes very beautiful and chirping birds with colorful feathers. Most of the Aves can fly except some flightless birds like an ostrich. The brief differentiation of Aves is due to the presence of beak, plumage, modified forelimbs into wings, modified hindlimbs for walking, swimming, or clasping the tree branches.

Birds don’t have oil glands on their skin; hence their skin is dry. The endoskeleton of birds is bony, ossified, and long bones are hollow with an air cavity. Their heart is four-chambered while the digestive tract is present with two additional chambers, namely crop and gizzard. Homeothermic warm-blooded Aves can regulate their body temperature according to the surround. Lungs and air sacs help in the respiration process—for example, crow, pigeons, parrot, etc.

Mammalia

Animals possessing mammary glands are categorized under the class Mammalia. Mammalians can present in ice cops, deserts, mountains, forests, caves, and grasslands. Mammary glands are milk-producing glands through which mammalian mothers feed their babies and provide nutrition. Two pairs of limbs for all types of activities are present in mammals.

Skin with hairs is the second unique characteristic of mammals, and they also have pinnae that are external ears. Different types of teethes with the jaw are one more important feature seen in mammals. They have a four-chambered heart. Their body temperature is independent of environmental conditions because they are homeothermic. Mammals can fly and live in water too—for example, platypus, rat, dog, cat, etc.

From all the detailed descriptions of chordates and vertebrates above, we can conclude that.