Ch28

Chapter 28

KINGDOM ANIMALIA

CHARACTERISTICS The following characteristics describe most animals: 1. Diploid Diploid multicel multicellula lularr eukaryo eukaryotes. tes. 2. Cells Cells are specializ specialized ed and organi organized zed into tissue tissues s organs organs etc. etc. !. "eterotro "eterotrophs phs that that inhabit inhabit the the sea fresh fresh water water and and land. land. #. $ost are are capable capable of locomo locomotion tion at at some stage stage of their their li%es. li%es. &. $ost can respond respond adapti%ely adapti%ely to e'ternal stimuli stimuli and ha%e well well de%eloped de%eloped sense organs organs and and ner%ous system. (. $ost reproduce reproduce se'ually se'ually with large non)motile non)motile eggs eggs and and small flagellate flagellated d sperms. *. The diploid diploid zygote produced produced by by fertilization fertilization di%ides by by mitotic di%isions di%isions resulting resulting in a ball of cells that usually hollows out to become a blastula. +ponges are an e'ception.  ,bout !& !& phyla the the ma-ority of of which are are in%ertebrates. in%ertebrates.

CLASSIFICATION ased on type of / 1. ody ca%ity ca%ity:: acoelom acoelomate ate pseudocoel pseudocoeloma omates tes coelomat coelomates. es. 2. De%elop De%elopment mental al pattern: pattern: protostom protostomes es deuteros deuterostome tomes. s. !. ody ody symme symmetry try:: radial radial bilater bilateral. al. Types of sectioning a specimen: • • •

Sagittal section di%ides section di%ides the body into right and left arts. arts . Cross or trans!erse section di%ides section  di%ides the body into anterior and osterior arts. arts . Frontal section di%ides section di%ides the body into dorsal and !entral arts. arts .

Coelom or body ca%ity is fluid)filled space located between the outer body wall and the digesti%e tube. 0erm layers: • • •

ndoderm forms the lining of the digesti%e tract. $esoderm forms most body structures: muscles bones etc. ctoderm gi%es rise to the outer co%ering of the body and the ner%ous system if present3.

Dilo"lastic animals Dilo"lastic  animals cnidarians and ctenophores3 ha%e two germ layers. Trilo"lastic animals Trilo"lastic  animals ha%e three germ layers.

 ,nimals may be... • • •

Acoelo#ate: Acoelo#ate : lack coelom or body ca%ity e.g. cnidarians ctenophores flatworms.. $se%docoelo#ate&  coelom is partially lined with mesoderm e.g. roundworms rotifers.. Coelo#ate: Coelo#ate : coelom is completely lined with mesoderm.

 ,nimals can can be classified classified as rotosto#es if rotosto#es if the blastopore de%elops into the mouth and de%terosto#es if de%terosto#es  if it de%elops into the anus. Deuterostomes and protostomes ha%e different pattern of clea%age: • •

Radial clea!age is clea!age  is characteristic of deuterostomes4 Siral clea!age is clea!age  is followed by protostomes.

5rotostomes also ha%e a deter#inate clea%age deter#inate  clea%age in which the fate of the embryonic cells is fi'ed %ery early in de%elopment. Deuterostomes ha%e an indeter#inate clea%age indeter#inate  clea%age in which each cell keeps longer the capacity to de%elop into a full organism. Schi'ocoel( method Schi'ocoel(  method of coelom formation is characteristic of protostomes. Deuterostomes follow the enterocoel( pattern enterocoel( pattern of coelom formation.

$H)L*M $ORIFERA 1. $ulticellular4 body a loose aggregation of cells of mesenchymal origin. 2. ody with pores  ostia3 ostia3 canals and chambers that ser%e for passage of water to the central ca%ity songocoel songocoel3 3 and out of the open end the osc%l%#. osc%l%# . !. ,bout 6777 species ha%e been identified4 all are auatic and mostly marine. #. +ymmetry radial or none. &. pidermis of flat pinacocytes4 most interior surfaces lined with flagellated collar cells choanocytes3 that create water currents4 a gelatinous protein matri' called #esoh(l #esoh(l which contains amebocytes collencytes secrete collagen3 and skeletal elements spicules3. (. +keletal structure of calcareous Class Calcarea3 or siliceous crystalline spicules Class "e'actinellida3 "e'actinellida3  or fibrillar collagen a protein and often combined with %ariously modified collagen spongin3 fibrils Class Demospongiae3. *. 9o organs or true tissues4 cells form a loose association but there is di%ision of labor4 digestion intracellular4 e'cretion and respiration by diffusion. 8. eactions to stimuli apparently local and independent4 ner%ous system probably absent. 6. ,ll adults sessile and attached to substratum.

17. ,se'ual reproduction by buds or gemmules and se'ual reproduction by eggs and sperm4 most are hermaphroditic4 free)swimming ciliated lar%ae. $H)L*M CNIDARIA 1. ntirely auatic4 some in fresh water but mostly marine. ,bout 17777 species. 2. adial symmetry or biradial radial and bilateral3 symmetry around a longitudinal a'is with oral and aboral ends4 no definite head. !. Two basic body forms: polyp and medusa. #. 'oskeleton or endoskeleton of chitinous calcareous or protein components in some. &. ody with two layers epidermis and gastrodermis4 with mesoglea  dilo"lastic34 dilo"lastic 34 mesoglea with cells and connecti%e tissue in some  trilo"lastic3. trilo"lastic3. (. Gastro!asc%lar ca!it( or coelenteron  often branched or di%ided with septa3 with a single opening that ser%es as both mouth and anus4 e'tensible tentacles usually encircling the mouth or oral region. *. Cnidoc(tes stinging Cnidoc(tes  stinging cells3 located in the epidermis and gastrodermis contain special stinging organelles called ne#atoc(sts4 ne#atoc(sts 4 nematocysts abundant on tentacles where they may form batteries or rings. 8. 9er%e net with symmetrical and asymmetrical synapses4 some sensory organs4 diffuse conduction. 6. $uscular system epitheliomuscular type3 of an outer layer of longitudinal fibers at base of epidermis and an inner one of circular fibers at base of gastrodermis4 modifications of this plan in anthozoans such as separate bundles of independent fibers in the mesoglea. 17. eproduction by ase'ual budding in polyps3 or se'ual reproduction by gametes in all medusae and some polyps4 se'ual forms monoecious or dioecious4 planula lar%a. 11. 9o e'cretory or respiratory systems. 12. 9o coelomic ca%ity.

Class H(dro'oa ) H(dro'oa  ) $ost hydrozoans are marine and colonial in form and typically include both the medusa and polyp stage in their life cycle. +ome howe%er ha%e no medusa stage and some occur only as medusae and ha%e no polyp stage. 'amples: "ydra ;belia. Class Sc(ho'oa ) Sc(ho'oa  ) Class +cyphozoa -ellyfishes3 includes most of the larger