Zoology

Intro­duc­tion 🔹 The king­dom Ani­malia con­sists of mul­ti­cel­lu­lar organ­isms that are clas­si­fied based on their lev­els of orga­ni­za­tion, body sym­me­try, and coelom (body cav­i­ty).🔹 This clas­si­fi­ca­tion helps in under­stand­ing struc­tur­al com­plex­i­ty, evo­lu­tion­ary rela­tion­ships, and func­tion­al adap­ta­tions in dif­fer­ent ani­mal groups. Clas­si­fi­ca­tion of Ani­malia Based on Struc­tur­al Com­plex­i­ty Cri­te­ria Types Key Fea­tures Exam­ples (Phy­lum) Lev­els of Orga­ni­za­tion Cel­lu­lar Read more…

NOTOCHORD: CHORDATES:Ani­mals that pos­sess a noto­chord. NON-CHORDATES:Ani­mals that do not form a noto­chord. Exam­ples: Porifera to Echin­o­derms.

SEGMENTATION: In some ani­mals, the body is exter­nal­ly and inter­nal­ly divid­ed into seg­ments with a ser­i­al rep­e­ti­tion of at least some organs. Exam­ple: in earth­worm, the body shows this pat­tern called metamer­ic seg­men­ta­tion and the phe­nom­e­non is known as metamerism.

Body Cav­i­ty: The pres­ence or absence of a cav­i­ty between the body wall and the gut wall is a key fac­tor in ani­mal clas­si­fi­ca­tion. COELOM: A body cav­i­ty that is ful­ly lined by meso­derm. Coelo­mates: Ani­mals that pos­sess a true coelom. Exam­ples include: Annelids Mol­luscs Arthro­pods Echin­o­derms Hemi­chor­dates Chor­dates PSEUDOCOELOM: Read more…

Ani­mal Sym­me­try: Ani­mals can be cat­e­go­rized based on their body sym­me­try. ASYMMETRY: Sponges are most­ly asymmetrical.No plane pass­ing through the cen­ter can divide them into equal halves. RADIAL SYMMETRY: Coe­len­ter­ates, ctenophores, and echin­o­derms exhib­it radi­al symmetry.Any plane pass­ing through the cen­tral axis of the body divides the organ­ism into two Read more…

DIGESTIVE SYSTEMS: Incom­plete Diges­tive Sys­tem: Sin­gle open­ing to the outside.This open­ing serves as both mouth and anus. Exam­ple: Platy­helminthes (flat­worms). COMPLETE DIGESTIVE SYSTEM: Two open­ings: mouth and anus.Food enters through the mouth and waste exits through the anus. CIRCULATORY SYSTEMS: OPEN CIRCULATORY SYSTEM: Blood is pumped out of the heart.Blood Read more…

Lev­els of Orga­ni­za­tion in Ani­malia MULTICELLULARITY: All mem­bers of Ani­malia are mul­ti­cel­lu­lar. How­ev­er, the orga­ni­za­tion of these cells varies sig­nif­i­cant­ly. CELLULAR LEVEL OF ORGANIZATION: Exam­ple: Sponges Descrip­tion: Cells are arranged as loose aggre­gates. There is some divi­sion of labor among cells, but no true tis­sues are formed. TISSUE LEVEL OF Read more…

Need for Clas­si­fi­ca­tion: There are over a mil­lion species of ani­mals described, mak­ing clas­si­fi­ca­tion cru­cial. Clas­si­fi­ca­tion helps in orga­niz­ing ani­mals based on their sim­i­lar­i­ties and dif­fer­ences. It also helps in assign­ing a sys­tem­at­ic posi­tion to new­ly dis­cov­ered species. Com­mon Fea­tures Across Ani­mal Species: Despite dif­fer­ences in struc­ture and form, ani­mals Read more…