Inter-relationships of classification, Biology

Assignment Help:

Inter-relationships of Classification

The aim of classification is to put together organisms on the basis of their similarities. But the question is what type of similarities? You know that fish and whales live in water; birds and butterflies live in air. Should we place fish and whales, in one group and birds and butterflies in another? Perhaps you are tempted to do so because fish and whales have organs to swim; birds and butterflies possess wings to fly. One of the early biologists, Pliny, in fact, classified animals on the basis of such analogous organs, that is organs that serve the same function and have similar appearance but have different evolutionary origins However, with the advancement in knowledge about the structure of animals it was revealed that the fish and whales or birds and butterflies have more differences than similarities between their body characters.

For example, fish respire using gills while the whales have lungs for this function. Similarly, birds have an internal skeleton whereas insects like butterflies lack it; instead they have an exoskeleton. Karl Linnaeus recognised these basic differences and based his system-of classification on the principle of homology. Homologous organs are those with the same evolutionary origin but which may not necessarily have the same appearance or serve the same function. For example, if you examine the fore-limbs of a man, the wing of a bat and the flipper of the whale (all mammals) you will see that in each case, though the function and the appearance of each of the fore-limbs are different, their basic skeletal plan is the same and they are homologous.

Furthermore, fossil records show that they all have a common evolutionary origin from the forelimbs of ancient amphibians. Thus, we conclude that all animals with pentadactyl forelimbs are related. Thus classification based upon homology reveals an inherent relationship among groups. In other words, it tells us that all creatures sharing basic structural features are related to each other and have evolved from a common ancestor.


Related Discussions:- Inter-relationships of classification

Which cells is the nervous tissue constituted, Q. Of which cells is the ner...

Q. Of which cells is the nervous tissue constituted? How is the generic function of this tissue related to the characteristics of the main cell type that forms it? The nervous

Biota of lakes, Biota of Lakes Lakes exhibit life zones. So far you h...

Biota of Lakes Lakes exhibit life zones. So far you have been reading about the vertical zonation of lakes. The lakes can be divided into horizontal zones as well. This divis

What are the main functions of the blood, What are the main functions of th...

What are the main functions of the blood? The blood is a means of substance transportation all by the body. The blood distributes nutrients, oxygen, antibodies, hormones, and c

Haematology, differenciate between plasma and serum

differenciate between plasma and serum

Explain phylum tracheophyta, Phylum Tracheophyta Tracheophytes mean vas...

Phylum Tracheophyta Tracheophytes mean vascular plants. Tracheophyta includes ferns, the gymnosperms and the flowering plants. They have appeared some 400 million years ago, an

Explain vernalisation, Name the state in humans in which the blood choleste...

Name the state in humans in which the blood cholesterol content becomes abnormally high. a) Explain vernalisation. b) Many villagers near Industrial area vary from "blue bab

What is peri-implant disease, Q. What is Peri-Implant Disease? The term...

Q. What is Peri-Implant Disease? The term peri-implantitis is used to describe the boneloss around an implant. This may be induced by stress or bacteria or a combination of bot

Decomposers, 5 beneficial effects of decomposers and 2 harmful effects

5 beneficial effects of decomposers and 2 harmful effects

Methods of virus, How Viruses Multiply? Obligatory parasitism - Outsi...

How Viruses Multiply? Obligatory parasitism - Outside cells viruses are nonliving, inactive   particles but after entering into live cells these multiply fast by replication

Radioactive labelling, Radioactive Labelling Radioactive labelling me...

Radioactive Labelling Radioactive labelling method has been effectively applied on the chick blastoderm. The method includes labelling one embryo (donor) and grafting a part

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd