Question

write a brief about progressive changes in animal classification ........please answer its really urgent friends.......

Answer 1

The classification system for animals* has been hotly debated and frequently changed since it was created 300 years ago, but now researchers have actually found a genetic basis which confirms that part of the system we use today is actually pretty accurate—and they think this part can be defined even more specifically down to the genetic level

Answer 2

Answer:

Depending on different criteria for classification,all  life form have been classifies chronologically into two kingdoms, three kingdoms, four kingdoms, five kingdoms and now into three domains or six kingdoms.  

Explanation:

1. Two Kingdom Classification ( Before 1969)- In the past all the organisms had been divided into two groups, plants and animals mainly on the basis of presence or absence of cell wall. Linnaeus ( father of Taxonomy) founded two kingdoms - Kingdom Plantae and Kingdom Animalia.

2. Three Kingdom Classification- Haeckel (1866) separated Unicellular animals, algae, and fungi from the other organisms on the basis of lack of tissue differentiation. The new group was called Kingdom Protista. Therefore, the three kingdoms were Kingdom Protista, Kingdom Plantae & Kingdom Animalia.

3. Four Kingdom Classification - A study under the newly invented microscope made it clear that bacteria and related organism have a different nuclear structure as compared to the others. Copeland (1956) created a separate Kingdom of monera for them. This divided the living world into four kingdoms- Monera, Protista, Plantae and Animalia. In this system, Fungi was still classified under kingdom Plantae

4. Five kingdom Classification ( from 1969 to 1990)- R.H.Whittaker (1969) sperated the fungi based on the saprophytic mode of nutrition, thus creating five kingdoms, namely Monera, Protista, Plantae, Fungi and Animalia.

5. Three Domains of Life ( Six kingdom Classification) (1990-Present) - Three domain system of classification was introduced by Carl Woese that divides life forms into archaea, bacteria and eukarya domain based on the RNA studies.

• Domain Archaea- it consists of Kingdom Archaebacteria, which are early prokaryotes livivg in extreme environments like hot springs, extreme salinity etc.

• Domain Bacteria- the domains contains Kingdom Eubacteria, which are bacteria, mycoplasma, actinomycetes, cyanobacteria etc.  

• Domain Eukarya-  all the eukaryotic life forms fall under this domain. there are four kingdoms under it- Protista, Fungi, Plantae and Animalia.