Classification of Animal-For NEB

Classification of Animal-For NEB

Classification of Animal-For NEB


Characteristic considered for classification of animals:-

  • Habitat:- It is the place where the organism lives. On the basis of habitat animals are classified in the following types:-
    • Aquatic:- Animals living in water are considered as Aquatic animals. It may be of two types:-
      1. Fresh water (i.e. animals living in River, lakes, pond etc.)
      2. Marine (i.e. animals living in Seas or Oceans)
    • Terrestrial:- Animals living on land. They maybe :-
      • Aerial :- Animals flying in air.
      1. Arboreal:- Animals living on trees.
      2. Subterranean:- Animals living in burrows.
      3. Cursorial :- Animals that Are specifically adapted to run.
    1. Other terms related witha habitat:-
      • Solitary:- Animals which lives alone.
      1. Sessile:- Animals whose stalk is absent and are fixed in one place.
      2. Free swimming :- Animals which move freely in water.
      3. Lentic :- Animals inhabiting or living in standing water bodies.
      4. Benthic :- Animals living on the bottom of sea.
      5. Sedentary :- Animals fixed to some substratum.
      6. Littoral :- Animals living in the intertidal zone of seacoast.
      7. Colonial:- Animals living together in group or colony.
      8. Stalked:- Animals whose stalk is present.
  • Cellularity:- The living organisms are made up of cells. On the basis of number of cells, the living organisms are of two types:-
    • Unicellular or acellular:- If the organism’s body is made up of a single cell performing all the life functions, then the organism is considered as unicellular or acellular organism. For example:- Protozoans.
    • Multicellular:- If the organism’s body is made up of many cells that become specialized to perform specific functions for the entire body of the organism is considered as multicellular organism.
  • Germ layer:- Germ layer appears during gastrula stage and later give rise to distinctly different tissue and organs systems in the adult. On the basis of the cellular layers found in animals, they are of 2 types:-
    • Diploblastic animals [Gr., diplos= double; blaste= to sprout] :-
      Animals having two germ layer in the body i.e. The outermost layer ectodermecto=outer ; derm = skin) and the innermost layer endoderm (endo=inner; derm= skin). The radiate animals such as cindarians are generally considered to be diploblastic.
    • Triploblastic Animals [Gr., treis= triple; blaste= to sproute]:-
      Animals having three germ layers in the body i.e. The outermost layer ectoderm, the innermost layer endoderm and the middle layer between endoderm and ectoderm i.e mesodermal layer. Most of tge metazoans (Bilateria) are triploblastic animals.
  • Body organisation:- Depending upon the degree of complexity, there are five different grades of organisation in animals. They are :-
    • Protoplasmic grade or molecular grade:- It is the lowest organisation. Protoplasmic or acellular grade occurs in protozoa and other unicellular organisms. All the life activities are conducted by a single cell which is considered as both structural and funtional unit.
    • Cellular grade:- Cells perform all its vitial activities independently of each other. There is no coordination between the cells. So tissue is absent. It comprises a loose association or aggregation of cells that are functionally differentiated. Porifers exhibit cellular grade of organisation. These are simplest multicellular animals.
    • Tissue grade:- An aggregation of cells which are of similar shape, structure, origin and perform specific function collectively. Best example of a tissue in Cindarians is the nerve net in which the nerve cells and their processes form a definite tissue structure and have coordination.
    • Organ grade :- This grade is aggregation of tissues into organ. Organs usually consists of more one kind of tissue. It was first appeared in the flat worms (Platyhelminthes).
    • Organ-System Grade:- When organs work together to perform some function, we have the highest level of organisation i.e. organ-system. Majority of animal phyla demonstrate organ-system type of organisation.
  • Body plan:- There are 3 basic types of body plan in animals namely cell aggregate, blind sac and tube-within-tube body plan.
    • Cell Aggregate Body Plan:- The body contains numerous cells but they function almost independently because the cells are not organised into tissues. There is no germ layers, no germ tissues or organ. It is exhibited by sponges which are parazoans.
    • Blind (Hollow) Sac Plan:- The body contains a single cavity with the opening or mouth. Blind sac body plan is exhibited by some eumetazoans like Cnidarians and flatworms.https://khullanote.com/wp-content/uploads/2020/07/IMG_20200718_151928-1024x780.jpg
    • Tube-within-tube Body Plan:- Their body consists of two tubes, the outer body wall and the inner gut. Tube-within-tube Body Plan is of two types:-
      • Protostomic:- The mouth of the digestive tract develops first in the embryo and anus is formed later. Eg. Roundworms, Annelids, Arthopods and Molluscs.
      1. Deuterostomic:- The anus of the digestive tract develops first in embryo and mouth is formed later. Eg:- chordates and echinoderms.
        https://khullanote.com/wp-content/uploads/2020/07/IMG_20200718_153817-1-978x1024.jpg
  • Symmetry:- When the body can be divided into two similar parts through one or more planes. On the basis of planes of division, symmetry is of the following types:-
    • Spherical Symmetry:- It is found in animals whose body resembles a sphere. The body can be divided into two equal halves by any plane passing through the center of the body. For example:- Volvox, Heluozoa , Radiolaria.
    • Bilateral Symmetry:- The body which is divisible into two similar halves through one median plane only. Each half is mirror to the other one. It is strongly associated with cephalization, which is the modification of anterior or oral end of the animal into definite head. Eg. Flatworms, mammals,etc.
    • Radial Symmetry:- The body is divisible into mirror halves by any one of the many longitudinal planes passing through the centre. The parts of the body of the organisms are arranged radially around a central axis. Radial symmetry is found in some sponges(Sycon), coelentrates and echinoderms.
    • Biradial Symmetry:- Only two planes passing through the longitudinal axis will produce mirrored halves. It is found in Sea anemones (Class:-Anthozoa) and Sea Walnuts [Comb jellies][Phylum:- Ctenophora]
  • Body surfaces:- Animals with bilateral symmetry show various surface like:-
    • Anterior End:- The end which usually moves forward and bears the mouth.
    • Posterior End:- The end which usually bears the anus or cloacal aperture. It lies to anterior end.
    • Dorsal Surface:- The parts which are away from the ground in the natural position.
    • Ventral Surface:- The part facing towards the ground.
    • Lateral Surfaces:- The parts towarfs the sides of the body.
    • Medial:- The part towards the central longitudinal axis of the body.
  • Segmentation/ Metamerism:- Segmentation/Metamerism in some Bilateria is the serial repetition od similar parts along the length of an animal.
    • Unsegmented:- Body without a linear series of segments. For examples:- Roundworms, Molluscs, Echinoderms etc.
    • Metamerically Segmented:- Body with a linear series of segments, the segments are interdependent with each other and work together. All segments are in the same stage of maturation. For examples:- Annelids, Arthropods and Chordates have metamerically segmented body.
    • Pseudosegmented:- Body with many false segments but are independent with each other. Body grows by addition of new segments from the anterior end. The segmentation in flatworms such as tapeworm is termed as pseudometamerism, the body is divided into many segments known as proglottids.
  • Body Cavity OR Coelom:- A body cavity is a fluid-filled space between outer body wall and the gut (Alimentary Canal). It contains the major internal organs.On the basis of coelom, animals can be:-
    • Acoelomates:- Animals without coelom or body cavity are called Acoelomates. The coelentron is an enclosed part of the outside world. In the flatworms, the region between the ectodermal epidermis and the endodermal digestive tract is completely filled with mesoderm in the form of a spongy mass of space filling cells called parenchyma. For example:- Porifera, Coelenterata and flatworms.
    • Pseudocoelomates (=Blastocoelomates):- Animals which have cavities not entirely lined by peritoneum [=thin cellular membrane derived from mesoderm ]. Such cavity is called as pseudocoel. Embryologically, a pseudocoel may be a persistent blastocoel or possibly derived from vacuoles within cells. For example:- Nematodes.
    • Coelomates/ Eucoelomates:- Animals with true coelom. True coeloms are secondary body cavities bounded on all the sided by mesodermal peritoneum. The true coelon arises within the mesoderm itself and may be formed by one of two methods, schizocoelous or enterocoelous. The schizocoel is formed by the splitting of mesodermal bands that originate from the cells in the blastopore region as in annelids, arthropods and molluscs. The enterocoel is formed from the pouches of the archenteron, or primitive gut as in echinoderms and some chordates.
    • Haemocoelomates:- Coelom filled with blood is called haemocoel and organisms are called haemocoelomates. Haemocoels occur in leech, arthropods, molluscans.
  • Skeleton:- Most of the animals have hard structure in the body for support and protection. It is of two types:-
    • Endoskeleton:- It is the skeleton inside the body. Cartilages and Bones form endoskeleton. Vertebrates have endoskeleton.
    • Exoskeleton:- It is the skeleton outside the body. It is chitinous cuticle in arthropods, calcareous shell in molluscs, feathers in birds, hair and nail in mammals are exoskeleton.
  • Locomotory organs or structures:-
    • Pesudopodia:- In amoeba
    • Flagella:- In Euglena
    • Cilia :- In Paramecium
    • Setae :- In earthworm
    • Parapodia :- In Nereis
    • Appendages :- In Arthopods
    • Muscular foot:- In Molluscs
    • Tube :- In Starfish
    • Fins :- In fishes
    • Limbs :- In Vertebrates
  • Nutrition:-
    • Holozoic:- Takes solid food
    • Holophytic:- Plant-like i.e. able to synthesize complex organic compounds by photosynthesis.
    • Saprozoic :- Animals feeding on dead organic matter.
    • Parasitic :- Animals which is dependent on the other organisms.
    • Saprophytic :- Plants feeding on dead organic matter.
    • Herbivorous :- Feeds on plants.
    • Carnivorous :- Feeds on animal flesh.
  • Digestion:-
    • Incomplete:- Anus is absent. Flatworms have incomplete alimentary canal.
    • Complete:- Mouth and anus or cloacal aperture are present. All animals of phylum Nematoda to Chordata have complete alimentary canal.
  • Respiratory Organs:- Protozoans, Porifers, roundworms donot possess any special respiratory organs. General body surface is the respiratory organ. Various respiratory organs in animals are as follows:-
    • Gills:- In aquatic animals such as fishes, tadpoles of amphibians some molluscs and some echinoderms.
    • Trachea:– In terrestrial arthopods such as insects.
    • Book lungs:- In arthropods.
    • Lungs:- In terrestrial animals such as:- Frogs, lizards, snakes, birds and mammals.
  • Circulation:-
    • Open circulatory:- Blood remains in large open spaces. For example:- In arthopods.
    • Closed Circulatory System:- Blood flows in definite vessels or in definite circuit. Blood is not in direct contact with the cells.
  • Types of animals on the basis of removal of Nitrogenous Wastes:-
    • Ammonotelic animals:-
      Excrete ammonia. For examples:- Protozoans, sponges, cnidarians, platyhelminthes, annelida, roundworms, bony fish, amphibian tadpoles, crocodiles etc.
    • Ureotelic Animals:-Excrete Urea. for examples:- Cartilaginous fish, semi-aquatic amphibians(e.g:- frog, toads), mammals.
      NOTE:- ascaris and Earthwormare both ammonoteluc and ureotelic (more ureotelic).
    • Uricotelic Animals:- Excrete Uric Acid. For example:- Most insects, birds, land snails, landreptiles (lizards and sanke).
    • Aminotelic:- Excrete amino acids. For examples:- Some molluscs (Unio) and some echinoderms (Asterias).
    • Guanotelic:- excrete guanine. Example:- spiders and Scorpions.
  • Excretory System:- Excretory organs, besides removing waste matter also regulate salt and water contents of the body and maintain homeostasis of the body.
    • General Body Surface:- In porifera and coelenterates.
    • Contractile Vacuole:- Jn protozoans.
    • Protonephridia (Flame cells/ solenocytes):- In flatworms.
    • Nephridia:- In annelids
    • Malpighian tubules, Coxal glands:- In Archnids (scorpion) and insects
    • Kidney:- In Vertebrates.
    • Protonephridia(Renette cells):- In Aschelminthes (Roundworm)
    • Renal organ or Renal Sac:- In Molluscs.
    • Antennary or green gland:- In Crustaceans (prawn)
    • Malphigian tubules and Urate cells:- In Millipedes.
  • Sex:-
    • Monoecious or bisexual or hermaphrodite:- Both male and female sex organs in one individual. Flatworms and Annelids are hermaphrodites.
    • Dioecious or unisexual:- Each individual with either male or female sex organ. Roundworms, Arthropods and all vertebrates are dioecious.
    • Sexual dimorphism:- Male and female animals can be distinguished externally. Peacock and peahen, lion and lioness.
    • Protandry:- Male reproductive organs (testes) mature earlier. Example:- Earthworm
    • Protogyny:- Female reproductive organs (ovaries) mature earlier. Example:- Human beings.
  • Reproduction:-
    • Asexual:-
      • Binary Fission :- Two daughter individuals are produced. It may be transverse or longitudinal. Paramecium and Euglena reproduce asexually by binary fission.
      1. Multiple Fission:- Many daughter individuals are produced from the single parent. Plasmodium multipies by multiple fission.
      2. Regeneration:-Ability to grow or develop the lost parts. Some coelenterates, Flatworms and echinoderms have regeneration power.
    1. Sexual Reproduction:- Male and female indivuals are involved.
  • Fertilization:-
    • External Fertilization:- Fusion of male and female gametes outside the body.
    • Internal Fertilization:- Fusion of male and female gametes inside the body.
  • Ovipary, Ovovivipary and Vivipary:- Depending upon the site of the development of embryo, animals are categorized into 3 types:-
    • Ovipary:- Development of embryo occurs inside the egg but outside the body of female.The phenomena occurs in egg laying animals. Amphibians, Birds, Reptiles, Several fishes, Arthopods, are oviparous.
    • Ovivipary:- Female retaining the eggs after fertilization and allowing the development of embryo inside the body but without providing other extra nourishment as the placenta is absent. The female animals, however, gives brth to the young ones. For example:- Sharks etc.
    • Vivipary:- Both fertilization and development of embryo occurs inside the body of the female. Placenta is present. The female animals give birth to the young ones.Metatherians and eutherians mammals are examples of viviparous.
  • Development:-
    • Direct:- Larval stage is absent.
    • Indirect:- Larval stage is present. The larvae lead independent life and undergo changes called metamorphosis to become an adult.

#animalkingdom#bodyplans#coelom#gradesoforganisation#segments#symmetry#systems