Classification of Animal Kingdom: Non Chordates and Chordates

Classification of Animal Kingdom helps identify many animals with various shapes and structures. With over a million animal species identified to date, the necessity for categorization becomes even more critical. 

• Classification of Animal Kingdom helps in understanding the ecosystem systematically.
• It helps in defining and placing newly described species in a logical order.
• Taxonomy is the process of classifying organisms systematically.
• Every species has been divided into five kingdoms, one of which being Kingdom Animalia, or the Animal Kingdom. 
• Animalia's members are further divided into Phyla, Classes, Orders, Families, and Genuses, depending on the characteristics.
• The arrangement of cells and symmetry of the body is the basis of the classification of organisms.

Key Terms: Classification of Animal Kingdom, Phyla, Classes, Orders, Families, Genuses, Animal Kingdom, Organisms, Non-Chordates, Chordates, Vertebrates, Reptiles, Amphibians, Mammalia

---

Classification of Animal Kingdom

[Click Here for Sample Questions]

Animals are multicellular eukaryotic creatures that absorb food into their bodies and grow from blastula embryos. More than 1.2 million species have been identified in the animal kingdom. 

• Comparative patterns of development and bodily features are used to classify animals.
• Behaviour, metabolic processes, and ancestry are other methods used to classify animal species into phyla.
• The process of classifying organisms into different hierarchies is called taxonomy.
• The presence or absence of a notochord is the main point of classification of the animal kingdom.
• Animals are classified on the basis of digestive or reproductive systems.
• The characteristics of notochord are similar to that of cartilage.
• It appears in the shape of the rod.

Classification of Animal Kingdom is divided into two categories of Non-Chordates and the Chordates

Non-Chordates

Non-chordates are animals that lack the rod-like structure in their bodies. Their phylum comprises creatures from the phyla Porifera, Hemichordata, Echinodermata, Mollusca, Arthropoda, Annelida, Aschelminthes, Platyhelminthes, Ctenophora, and Coelenterata. 

• They are all regarded as members of the non-chordates category.
• The circulatory systems of these species are in open form.
• They tend to use both sexual and asexual reproduction. 

Characteristics of Non-Chordates

Non-chordates have the following general characteristics:

• They are essentially pseudocoelomate, coelomate, triploblastic, or cylindrical creatures.
• Fertilization occurs indefinitely, although certain species have been shown to have internal fertilization.
• Most of the time, precise sexual differentiation among group members is impossible.
• The non-chordates breathe by using their body surface, trachea, or gills.

Classification of Animal Kingdom

​Read More:

Chordates

Chordates are animal bodies that have a notochord present at any time during their lives. Pharyngeal gill slits and a hollow nerve cord are distinguished members of this group.

• These animals have a number of fundamental features, including:
• They are symmetrical on both sides with triploblastic, and coelomate with organ-system organisation.
• Chordates have a tail that is in the shape of post-anal.
• The circulatory system in the human body is closed.
• The notochord is found only in the larval tail of certain Phylum Chordata members.
• It is present throughout their lives from head to tail region in others.
• Chordates are divided into numerous sub-groups, with Protochordates being one of the earliest to emerge.

Types of Chordates

Urochordata, Cephalochordata, and Vertebrata are the three subphyla of the Chordata phylum.

• Subphylum Urochordata

Urochordata is a subphylum of the phylum ubphylum. It's also known as Tunicata, which refers to aquatic creatures. These creatures have a leathery coating around their bodies (similar to a tunic, hence the name).

• Larvae are free-swimming, and the notochord is only found in the larvae's tails.
• After resting on the bottom, they convert into sessile adults.
• Hermaphrodites are the most common kind.

• Subphylum Cephalochordata

Cephalochordata is a subphylum of the phylum Cephalochordata. It mostly comprises of tiny, fish-like aquatic creatures with a notochord that runs the length of their bodies.

• The creatures also have a big pharynx with many gill slits.
• The sexes of members of this subphylum are distinct.

• Subphylum Vertebrata

Vertebrata is a subphylum of the Vertebrata phylum. The notochord is present in the embryonic stages of this subphylum and is replaced by a vertebral column in adulthood.

• They have a heart with two, three, or four chambers, paired appendages for movement, and kidneys for excretion or osmoregulation.

Read More: Difference Between Frog and Toad

---

Vertebrates Classification

[Click Here for Sample Questions]

Vertebrates are classified into five groups in the subphylum Vertebrata. All animal species that have evolved a vertebral column as well as an internal skeleton belong to these five groups of vertebrates.

• There are approximately 66,000 vertebrate species in the phylum Chordata. 
• Vertebrates are distinguished by bilateral symmetry, coelomic, triploblastic bodies, and complex tissue.

Characteristics of Vertebrates

The important characteristics of vertebrates are as follows:

• For body mobility, the presence of a genuine vertebral column and internal skeleton with muscle attachment sites is important.
• A muscular front-side heart has two, three, or four chambers.
• Kidneys are responsible for excretion as well as osmoregulation.
• Fins or limbs are examples of paired appendages.
• During the embryonic stage, the notochord is present in vertebrate.
• Vertebrates happen to be the only chordates with a central nervous system that includes a brain.

Classification of Vertebrates

Vertebrates are classified as follows:

Pisces (Fishes)

Fish are defined as "gill-bearing aquatic craniate creatures that lack digits on their limbs." This class has the most varied and extensive range of vertebrates, with about 30,000 species.

• 41% of the population lives in fresh water, 58 percent resides in the sea region.
• The remaining 1% travels between the two.
• The species' body structure typically follows the head, trunk, and tail pattern.
• All fishes lack fins, which are divided into two types: paired and unpaired fins.
• Paired fins consists of pelvic and pectoral fins.
• Unpaired fins consists of anal, caudal and dorsal fins.

Amphibia

Amphibians are animals that can live on land and in water and are known for having a "double existence." Caecilians, toads, frogs, and salamanders are among the almost 3,900 species that make up this animal group.

• Amphibians are unable to regulate their body temperature.
• Their skin types limit the range of conditions in which they may live, from damp to hot.
• They need both gills and lungs as they breathe with gills during the larval stage and with lungs when they reach maturity.

Read More:

Reptilia

All turtles, crocodiles, lizards, and snakes on the planet are classified as reptiles. Reptilia is a class of animals that includes almost a thousand species on the globe. They're further broken down into the following categories:

• Testudines are approximately 3000 species of tortoises, terrapins and turtles.
• Squamata are about 9150 species of worm lizards and snakes.
• Sphenodontia ( 2 tuatara species)
• Crocodilia are 23 species of gharial, alligators, caiman, and crocodiles

Class Aves (Birds)

These are cold-blooded, bipedal feathery creatures that can maintain a consistent body temperature range. The appendages on the front of their bodies are fashioned like wings.

• Most creatures in this class can fly high into the sky, though there are a few exceptions.
• There are almost 9,000 species in the Aves class.

Mammalia

This category includes warm-blooded animals with hair on their bodies and the ability to make milk. This group of mammals is the only one that feeds milk to their offspring.

• There are almost 4,000 mammal species on the planet.
• Humans, Koalas, cows, and other animals are regarded to be part of this group.

---

Things to Remember

• Classification of Animal Kingdoms is classified on the basis of the presence of notochord.
• Most organisms belonging to this category are eukaryotic in nature.
• These type of organisms cannot produce their own food.
• Tissue level refers to cells performing similar functions within the tissues.
• The classification is also based on the process of fertilisation.