Introduction
One of the foremost basic styles of classification of animals is the presence or absence of the notochord. Basically Notochord is a flexible rod-like structure of cells, working as a support for the body. Hence, 2 major terms exist, namely: Chordates and Non-chordates.
Chordates
The spine could be a versatile rod created out of a material same as animal tissue. If examining an animal and it encompasses a spine throughout any stage of its life, it’s classified as a chordate. Contrary to standard belief, chordates don’t solely embody vertebrates.
There are invertebrates that possess a spine throughout some purpose in their lives and hence, they are classified as chordates. So all vertebrates are chordates however not all chordates are vertebrates.
Non-chordates
Non-chordates are animals which do not have a spine – the rod-like elastic structure that supports the body. This phylum consists of a little cluster of worm-like, marine species with organ-system level of organisation.
Members of phylum Porifera, Coelenterate, Ctenophore, Platyhelminthes, Nematode, Annelida, Arthropod, Mollusca, Echinodermata and Hemichordate make Non-chordates.
The general characteristic options of non-chordates are:
They are cylindrical, triploblastic, coelomate, or pseudocoelomate animals.
Respiration in these animals takes place through gills, trachea or body surface.
Most days, sexes cannot be distinguished among the members.
Fertilisation is external, although internal fertilisation may happen in some species.
Chordates
Chordates are animals characterised by the presence of a spine at some stage throughout their development. Members possess a hollow nerve twine and tubular cavity gill slits. The different general characteristic options of Chordates are:
- They are bilaterally symmetrical, triploblastic, and coelomate with the organ-system level of organisation
- They hold a post-anal tail
- The body includes a closed cardiovascular system
- In some members of phylum, the spine is a gift solely within the larval tail, and in some, its gift throughout their life from head to tail region
Phylum Chordata is split into 3 subphyla: urochordata, cephalochordata and vertebrata
Subphylum – subphylum Tunicata
It can also be stated as Tunicata that are marine animals. The body of those animals is encircled by a leathered covering. Larvae are unattached, the spine is given solely within the tail of larvae and when settling on the river bed, they get remodelled into sessile adults. They’re usually hermaphrodites.
Examples embody – Ascidians, Doliolum, Oikopleura, etc.
Subphylum – Cephalochordata
It in the main consists of tiny, fish-like marine animals within which the spine is extended on the whole body. The animals even have a throat that is giant with various gill- slits. Members of this taxon have separate sexes.
Example embodies – cephalochordate or cephalochordate.
Subphylum – subphylum Craniata
In this taxon, the spine is a gift within the embryonic stages and is replaced by a spine within the adult. They need a pair of, three or four divided hearts, paired appendages for locomotion and kidneys for excretion or osmoregulation.
Vertebrates Classification
The subphylum Craniata is split into 5 categories of vertebrates. These 5 categories of vertebrates comprise of all the species of animals and have developed spine moreover as an enclosed skeleton.
There are over 66,000 species of vertebrates known below phylum until date. The shaping feature of vertebrates is that their bodies are bilaterally symmetrical, coelomic, triploblastic, and with complicated differentiation of body tissues and organs.
Other characteristic options of vertebrates are:
- Presence of a real spine and internal skeleton with muscle attachment points for body movement
- A front-side muscular heart with 2, 3 or four chambers
- Kidneys for excretion and osmoregulation
- A paired appendage which can be fins or limbs
- Possess spine throughout the embryonic stage
- Vertebrates are the sole chordates to possess a brain as a section of the central systema nervosum
Classification of Vertebrates
- Pisces
- Amphibia
- Reptilia
- Aves
- Mammalia
Class Pisces (Fishes)
They are aquatic animals, having an efficient body and a combination of fins that are used for propulsion and movement. Moreover, fish are cold-blooded, however the invention of a brand new species in 2015 has modified this perception. The moonfish or the moon-fish could be a totally warm-blooded fish capable of controlling its temperature.
Examples of category Pisces include dogfish and Rohu.
Class Amphibia
They are usually composed of those organisms that are cold-blooded and need an aquatic environment to lay eggs. These organisms are majorly divided by the 2 pairs of limbs, sleek and damp skin for respiration. They possess protrusive eyes that are protected by multiple layers of eyelids. (Frogs have 3).
Examples of class are frog, toad, and salamander.
Class Reptilia
Class Reptilia contains those organisms that are poikilothermic in nature (cold-blooded). They’re characterised by osteoderms that type scales, bony plates or scutes on the skin. Reptiles generally are not deprived of external organs and a few reptiles like snakes are literally “deaf” and instead, acquire vibrations from the ground. Another superb sense that solely snakes possess is Thermoception. This suggests that snakes will see infrared light emitted by objects or prey.
Examples of class Reptilia are turtle, Wall lizard, Snake, etc.
Class Aves (Birds)
Most members have an efficient body specially designed to supply low air resistance throughout flight. In such birds, the forelimbs are changed into wings, with the facility coming back from breast muscles. Feathers play vital roles, from flight, thermal insulation to water-proofing. All members of this category are warm-blooded and are able to regulate their temperature.
Examples of Aves are Parrot, Pigeon, Duck, etc.
Class Mammalia
These organisms are distinguished by the presence of exocrine gland glands. They need 2 pairs of limbs for walking, grasping, swimming, flying, etc. Digits are supplied with claws, nails or hooves. Skin is roofed by hair and they have an Associate in nursing external organ known as pinnae. They’re warm-blooded animals.
Examples of class Mammalia embody monkeys, lions, bats, squirrels and humans.
Conclusion
Thus, classification of animals has led to a great diversified life on earth. Almost about 1.2M species of animals have been discovered, and more to be discovered and studied upon, it’s an endless process and will continue till mankind lasts.
Animals can also be classified based on habitats, i.e Terrestrial, Aquatic, Aerial, Arboreal, Amphibians.