Animal Kingdom Class 11 Notes Biology Chapter 4

 Page 1


Point to Remember
Basis of Classification :
 Animals are classified on the basis of following few fundamental features—
1. Levels of Organisation :
 (1) Cellular level : Cells are arranged as loose cell agg regates, e.g.,sponges.
(2) Tissue level : The cells performing the same function are arranged into
tissues, e.g., Coelenterates.
(3) Organ level : Tissues are grouped together to form organs, each
specialised for a particular function. e.g., platyhelminthes.
(4) Organ system level : organs are associated to form functional systems
e.g., Annelids, Arthropods, Molluscs, Echinoderms and Chordates.
  Example : Circulatory System.
 Open type : Blood pumped out through heart. Not confined to blood vessels. 
Cells and tissues are directly bathed in it.
 Closed types : Blood is circulated through blood vessels (arteries,veins and 
capillaries)
2. Symmetry :
 ? Asymmetrical : Cannot be divided into equal halves through median plane
e.g., Sponges.
 ? Radial symmetry : Any plane passing through central axis can divide organism
into identical halves. e.g., coelentrates,Ctenophores and echinoderms.
 ? Bilateral symmetry : Only one plane can divide the organism into two identical
left and right halves e.g., Annelids and Arthropods.
3. Germinal Layers :
Diploblastic : Cells arranged in two embryonic layers i.e., external ectoderm
and internal endoderm. (Mesoglea may be present in between ectoderm and
endoderm) e.g., porifers and Coelentrates. (Cnidarians)
 Triploblastic : Three layers present in developing embryo i.e., ectoderm,
mesoderm and endoderm. e.g., Platyhelminthes to Chordates.
Page 2


Point to Remember
Basis of Classification :
 Animals are classified on the basis of following few fundamental features—
1. Levels of Organisation :
 (1) Cellular level : Cells are arranged as loose cell agg regates, e.g.,sponges.
(2) Tissue level : The cells performing the same function are arranged into
tissues, e.g., Coelenterates.
(3) Organ level : Tissues are grouped together to form organs, each
specialised for a particular function. e.g., platyhelminthes.
(4) Organ system level : organs are associated to form functional systems
e.g., Annelids, Arthropods, Molluscs, Echinoderms and Chordates.
  Example : Circulatory System.
 Open type : Blood pumped out through heart. Not confined to blood vessels. 
Cells and tissues are directly bathed in it.
 Closed types : Blood is circulated through blood vessels (arteries,veins and 
capillaries)
2. Symmetry :
 ? Asymmetrical : Cannot be divided into equal halves through median plane
e.g., Sponges.
 ? Radial symmetry : Any plane passing through central axis can divide organism
into identical halves. e.g., coelentrates,Ctenophores and echinoderms.
 ? Bilateral symmetry : Only one plane can divide the organism into two identical
left and right halves e.g., Annelids and Arthropods.
3. Germinal Layers :
Diploblastic : Cells arranged in two embryonic layers i.e., external ectoderm
and internal endoderm. (Mesoglea may be present in between ectoderm and
endoderm) e.g., porifers and Coelentrates. (Cnidarians)
 Triploblastic : Three layers present in developing embryo i.e., ectoderm,
mesoderm and endoderm. e.g., Platyhelminthes to Chordates.
4. Coelom (Body cavity which is lined by mesoderm)
 Coelomates : Have coelom e.g., Annelids, Arthropods, molluscs, Echinoderms,
Chordates etc.
 Pseudocoelomates : No true coelem as mesoderm is present in scattered
pouches between ectoderm and endoderm. e.,g., Aschelminthes.
 Acoelomates : Body cavity is absent e.g., Platyhelminthes.
5. Segmentation (A) True Metamerism : Found Annelida,Arthropoda,
Chordata :
 ? Segmentation is external as well as a internal in Annelids.
? Segmentation is external in Arthropods.
 ? Segmentation is internal in chordates.
 ? Metamerism : If body is externally and internally divided into segments
(metameres) with serial repetition of atleast some organs, then phenomenon is
called metamerism e.g., Earthworm. (B) Pseudometamerism : Found in
tapeworm. The proglottids (segments of tapeworm) budded off from neck
not embryonic in origin.
6. Notochord :
 ? Rod-like structure formed during embryonic development on t he dorsal side.
It is mesodermally derived e.g., Chordates.
 ? Non-chordates do not have notochord .e.g., porifera to echinoderms.
Phylum Porifera :
? Also called sponges.
? Are usually marine and asymmetrical.
? Have cellular level of organisation and diploblastic animals.
? Food gathering, respiratory exchange and removal of wastes occurs through
water canal system. Digestion intracellular.
? Ostia (minute pores on body), spongocoel (body cavity) and osculum help
in water transport. They are lined by choanocytes (collar cells).
? Body wall has skeleton of spicules or spongin fibres.
? Animals are hermaphrodite. Fertilisation internal. Development is indirect
(i.e., has a larval stage distinct from adult stage) e.g., Sycon, Euspongia.
Spongilla (Fresh water sponge)
Phylum Coelenterata :
? Also called Cnidarians.
? Are usually marine and radially symmetrical.
? Sessile or free swimming.
Page 3


Point to Remember
Basis of Classification :
 Animals are classified on the basis of following few fundamental features—
1. Levels of Organisation :
 (1) Cellular level : Cells are arranged as loose cell agg regates, e.g.,sponges.
(2) Tissue level : The cells performing the same function are arranged into
tissues, e.g., Coelenterates.
(3) Organ level : Tissues are grouped together to form organs, each
specialised for a particular function. e.g., platyhelminthes.
(4) Organ system level : organs are associated to form functional systems
e.g., Annelids, Arthropods, Molluscs, Echinoderms and Chordates.
  Example : Circulatory System.
 Open type : Blood pumped out through heart. Not confined to blood vessels. 
Cells and tissues are directly bathed in it.
 Closed types : Blood is circulated through blood vessels (arteries,veins and 
capillaries)
2. Symmetry :
 ? Asymmetrical : Cannot be divided into equal halves through median plane
e.g., Sponges.
 ? Radial symmetry : Any plane passing through central axis can divide organism
into identical halves. e.g., coelentrates,Ctenophores and echinoderms.
 ? Bilateral symmetry : Only one plane can divide the organism into two identical
left and right halves e.g., Annelids and Arthropods.
3. Germinal Layers :
Diploblastic : Cells arranged in two embryonic layers i.e., external ectoderm
and internal endoderm. (Mesoglea may be present in between ectoderm and
endoderm) e.g., porifers and Coelentrates. (Cnidarians)
 Triploblastic : Three layers present in developing embryo i.e., ectoderm,
mesoderm and endoderm. e.g., Platyhelminthes to Chordates.
4. Coelom (Body cavity which is lined by mesoderm)
 Coelomates : Have coelom e.g., Annelids, Arthropods, molluscs, Echinoderms,
Chordates etc.
 Pseudocoelomates : No true coelem as mesoderm is present in scattered
pouches between ectoderm and endoderm. e.,g., Aschelminthes.
 Acoelomates : Body cavity is absent e.g., Platyhelminthes.
5. Segmentation (A) True Metamerism : Found Annelida,Arthropoda,
Chordata :
 ? Segmentation is external as well as a internal in Annelids.
? Segmentation is external in Arthropods.
 ? Segmentation is internal in chordates.
 ? Metamerism : If body is externally and internally divided into segments
(metameres) with serial repetition of atleast some organs, then phenomenon is
called metamerism e.g., Earthworm. (B) Pseudometamerism : Found in
tapeworm. The proglottids (segments of tapeworm) budded off from neck
not embryonic in origin.
6. Notochord :
 ? Rod-like structure formed during embryonic development on t he dorsal side.
It is mesodermally derived e.g., Chordates.
 ? Non-chordates do not have notochord .e.g., porifera to echinoderms.
Phylum Porifera :
? Also called sponges.
? Are usually marine and asymmetrical.
? Have cellular level of organisation and diploblastic animals.
? Food gathering, respiratory exchange and removal of wastes occurs through
water canal system. Digestion intracellular.
? Ostia (minute pores on body), spongocoel (body cavity) and osculum help
in water transport. They are lined by choanocytes (collar cells).
? Body wall has skeleton of spicules or spongin fibres.
? Animals are hermaphrodite. Fertilisation internal. Development is indirect
(i.e., has a larval stage distinct from adult stage) e.g., Sycon, Euspongia.
Spongilla (Fresh water sponge)
Phylum Coelenterata :
? Also called Cnidarians.
? Are usually marine and radially symmetrical.
? Sessile or free swimming.
? Have tissue level of organisation.
? Are diploblastic (with mesogloea)
? Capture of prey, anchorage and defence occurs through cnidoblasts/cnidocytes
(have stinging capsules nematocytes) present on tentacles.
? Digestion extracellular and intracellular.
? Have a central gastro-vascular cavity and an opening, hypostome.
? Body wall of some composed of calcium carbonate. e.g. corals.
? exhibit two body forms : polyp and medusa e.g., Hydra, Aurelia.
? Alternation of generation between body forms called metagenesis ocurs in
Obelia where :
           Medusa   Polyp. (Sessile and cylindrical)
    (free swimming &
       umbrella shaped)
? e.g., Physalia, Adamsia, Pennatula, Gorgonia,Meandrina.
Phylum Ctenophora :
? Also called as sea walnuts or comb jellies.
? Are exclusively marine, radially symmetrical.
? Have tissue level organisation, are diploblastic.
? Digestion both extra and intracellular.
? Body has eight external rows of ciliated comb plates for locomotion.
? Show Bioluminescence (Property of living organisms to emit light).
? Hermaphrodite (sexes are not separate).
? Only sexual reproduction occurs. Exernal fertilization. Indirect development.
e.g., Ctenoplana, Pleurobrachia.
Phylum Plathyhelminthes :
? Also called as ‘flat worms’.
? Have dorsoventrally flattened body. Are mostly endoparasites in animals.
? Are bilaterally symmetrical, triploblastic, acoelomate,with organ level of
orgnisation.
? Absorb nutrients through body surface.
? Parasitic forms have hooks and suckers.
? ‘Flame cells’ help in osmoregulation and excretion.
Page 4


Point to Remember
Basis of Classification :
 Animals are classified on the basis of following few fundamental features—
1. Levels of Organisation :
 (1) Cellular level : Cells are arranged as loose cell agg regates, e.g.,sponges.
(2) Tissue level : The cells performing the same function are arranged into
tissues, e.g., Coelenterates.
(3) Organ level : Tissues are grouped together to form organs, each
specialised for a particular function. e.g., platyhelminthes.
(4) Organ system level : organs are associated to form functional systems
e.g., Annelids, Arthropods, Molluscs, Echinoderms and Chordates.
  Example : Circulatory System.
 Open type : Blood pumped out through heart. Not confined to blood vessels. 
Cells and tissues are directly bathed in it.
 Closed types : Blood is circulated through blood vessels (arteries,veins and 
capillaries)
2. Symmetry :
 ? Asymmetrical : Cannot be divided into equal halves through median plane
e.g., Sponges.
 ? Radial symmetry : Any plane passing through central axis can divide organism
into identical halves. e.g., coelentrates,Ctenophores and echinoderms.
 ? Bilateral symmetry : Only one plane can divide the organism into two identical
left and right halves e.g., Annelids and Arthropods.
3. Germinal Layers :
Diploblastic : Cells arranged in two embryonic layers i.e., external ectoderm
and internal endoderm. (Mesoglea may be present in between ectoderm and
endoderm) e.g., porifers and Coelentrates. (Cnidarians)
 Triploblastic : Three layers present in developing embryo i.e., ectoderm,
mesoderm and endoderm. e.g., Platyhelminthes to Chordates.
4. Coelom (Body cavity which is lined by mesoderm)
 Coelomates : Have coelom e.g., Annelids, Arthropods, molluscs, Echinoderms,
Chordates etc.
 Pseudocoelomates : No true coelem as mesoderm is present in scattered
pouches between ectoderm and endoderm. e.,g., Aschelminthes.
 Acoelomates : Body cavity is absent e.g., Platyhelminthes.
5. Segmentation (A) True Metamerism : Found Annelida,Arthropoda,
Chordata :
 ? Segmentation is external as well as a internal in Annelids.
? Segmentation is external in Arthropods.
 ? Segmentation is internal in chordates.
 ? Metamerism : If body is externally and internally divided into segments
(metameres) with serial repetition of atleast some organs, then phenomenon is
called metamerism e.g., Earthworm. (B) Pseudometamerism : Found in
tapeworm. The proglottids (segments of tapeworm) budded off from neck
not embryonic in origin.
6. Notochord :
 ? Rod-like structure formed during embryonic development on t he dorsal side.
It is mesodermally derived e.g., Chordates.
 ? Non-chordates do not have notochord .e.g., porifera to echinoderms.
Phylum Porifera :
? Also called sponges.
? Are usually marine and asymmetrical.
? Have cellular level of organisation and diploblastic animals.
? Food gathering, respiratory exchange and removal of wastes occurs through
water canal system. Digestion intracellular.
? Ostia (minute pores on body), spongocoel (body cavity) and osculum help
in water transport. They are lined by choanocytes (collar cells).
? Body wall has skeleton of spicules or spongin fibres.
? Animals are hermaphrodite. Fertilisation internal. Development is indirect
(i.e., has a larval stage distinct from adult stage) e.g., Sycon, Euspongia.
Spongilla (Fresh water sponge)
Phylum Coelenterata :
? Also called Cnidarians.
? Are usually marine and radially symmetrical.
? Sessile or free swimming.
? Have tissue level of organisation.
? Are diploblastic (with mesogloea)
? Capture of prey, anchorage and defence occurs through cnidoblasts/cnidocytes
(have stinging capsules nematocytes) present on tentacles.
? Digestion extracellular and intracellular.
? Have a central gastro-vascular cavity and an opening, hypostome.
? Body wall of some composed of calcium carbonate. e.g. corals.
? exhibit two body forms : polyp and medusa e.g., Hydra, Aurelia.
? Alternation of generation between body forms called metagenesis ocurs in
Obelia where :
           Medusa   Polyp. (Sessile and cylindrical)
    (free swimming &
       umbrella shaped)
? e.g., Physalia, Adamsia, Pennatula, Gorgonia,Meandrina.
Phylum Ctenophora :
? Also called as sea walnuts or comb jellies.
? Are exclusively marine, radially symmetrical.
? Have tissue level organisation, are diploblastic.
? Digestion both extra and intracellular.
? Body has eight external rows of ciliated comb plates for locomotion.
? Show Bioluminescence (Property of living organisms to emit light).
? Hermaphrodite (sexes are not separate).
? Only sexual reproduction occurs. Exernal fertilization. Indirect development.
e.g., Ctenoplana, Pleurobrachia.
Phylum Plathyhelminthes :
? Also called as ‘flat worms’.
? Have dorsoventrally flattened body. Are mostly endoparasites in animals.
? Are bilaterally symmetrical, triploblastic, acoelomate,with organ level of
orgnisation.
? Absorb nutrients through body surface.
? Parasitic forms have hooks and suckers.
? ‘Flame cells’ help in osmoregulation and excretion.
40
? Sexes not separate.
? Fertilisation internal. Many larval stages present. Planaria has high
regeneration capacity. e.g., Taenia, Fasciola.
Phylum Aschelminthes :
? Also called ‘round worms’.
? May be free living, parasitic, aquatic or terrestrial.
? Are bilaterally symmetrical, triploblastic, pseudocoelomate.
? Alimentary canal complete (has muscular pharynx), wastes removed through
excretory pore.
? Sexes separate. (dioecious)
? Females longer than males.
? Fertilisation internal. Development direct or indirect. e.g., Ascaris,Wuchereria,
Ancylostoma.
Phyum Annelida :
? Are aquatic or terrestrial, free-living or parasitic.
? Are bilaterally symmetrical, triploblastic, organ-system level of organisation
and metamerically segmented body.
? Are coelomate animals.
? Have longitudinal and circular muscles for locomation.
? Have closed circulatory system.
? Nereis (dioecious and aquatic annelid) has lateral appendages called parapodia
for swimming.
? Have nephridia for osmoregulation and excretion.
? Neural system consists of paired gangila connected by lateral nerves to a
double ventral nerve cord.
? Reproduction is sexual.
? e.g., Earthworm (Pheretima) and Leech (Hirudinaria) which are hermaph
rodites (i.e., monoecious).
Phylum Arthropoda :
? Largest phylum of Animalia.
? Are bilaterally symmetrical, triplobastic, segmented externally and organ
system level of organisation, coelomate.
? Body divisible into head, thorax, abdomen and has a chitinous exoskeleton.
Jointed appendages are present.
Page 5


Point to Remember
Basis of Classification :
 Animals are classified on the basis of following few fundamental features—
1. Levels of Organisation :
 (1) Cellular level : Cells are arranged as loose cell agg regates, e.g.,sponges.
(2) Tissue level : The cells performing the same function are arranged into
tissues, e.g., Coelenterates.
(3) Organ level : Tissues are grouped together to form organs, each
specialised for a particular function. e.g., platyhelminthes.
(4) Organ system level : organs are associated to form functional systems
e.g., Annelids, Arthropods, Molluscs, Echinoderms and Chordates.
  Example : Circulatory System.
 Open type : Blood pumped out through heart. Not confined to blood vessels. 
Cells and tissues are directly bathed in it.
 Closed types : Blood is circulated through blood vessels (arteries,veins and 
capillaries)
2. Symmetry :
 ? Asymmetrical : Cannot be divided into equal halves through median plane
e.g., Sponges.
 ? Radial symmetry : Any plane passing through central axis can divide organism
into identical halves. e.g., coelentrates,Ctenophores and echinoderms.
 ? Bilateral symmetry : Only one plane can divide the organism into two identical
left and right halves e.g., Annelids and Arthropods.
3. Germinal Layers :
Diploblastic : Cells arranged in two embryonic layers i.e., external ectoderm
and internal endoderm. (Mesoglea may be present in between ectoderm and
endoderm) e.g., porifers and Coelentrates. (Cnidarians)
 Triploblastic : Three layers present in developing embryo i.e., ectoderm,
mesoderm and endoderm. e.g., Platyhelminthes to Chordates.
4. Coelom (Body cavity which is lined by mesoderm)
 Coelomates : Have coelom e.g., Annelids, Arthropods, molluscs, Echinoderms,
Chordates etc.
 Pseudocoelomates : No true coelem as mesoderm is present in scattered
pouches between ectoderm and endoderm. e.,g., Aschelminthes.
 Acoelomates : Body cavity is absent e.g., Platyhelminthes.
5. Segmentation (A) True Metamerism : Found Annelida,Arthropoda,
Chordata :
 ? Segmentation is external as well as a internal in Annelids.
? Segmentation is external in Arthropods.
 ? Segmentation is internal in chordates.
 ? Metamerism : If body is externally and internally divided into segments
(metameres) with serial repetition of atleast some organs, then phenomenon is
called metamerism e.g., Earthworm. (B) Pseudometamerism : Found in
tapeworm. The proglottids (segments of tapeworm) budded off from neck
not embryonic in origin.
6. Notochord :
 ? Rod-like structure formed during embryonic development on t he dorsal side.
It is mesodermally derived e.g., Chordates.
 ? Non-chordates do not have notochord .e.g., porifera to echinoderms.
Phylum Porifera :
? Also called sponges.
? Are usually marine and asymmetrical.
? Have cellular level of organisation and diploblastic animals.
? Food gathering, respiratory exchange and removal of wastes occurs through
water canal system. Digestion intracellular.
? Ostia (minute pores on body), spongocoel (body cavity) and osculum help
in water transport. They are lined by choanocytes (collar cells).
? Body wall has skeleton of spicules or spongin fibres.
? Animals are hermaphrodite. Fertilisation internal. Development is indirect
(i.e., has a larval stage distinct from adult stage) e.g., Sycon, Euspongia.
Spongilla (Fresh water sponge)
Phylum Coelenterata :
? Also called Cnidarians.
? Are usually marine and radially symmetrical.
? Sessile or free swimming.
? Have tissue level of organisation.
? Are diploblastic (with mesogloea)
? Capture of prey, anchorage and defence occurs through cnidoblasts/cnidocytes
(have stinging capsules nematocytes) present on tentacles.
? Digestion extracellular and intracellular.
? Have a central gastro-vascular cavity and an opening, hypostome.
? Body wall of some composed of calcium carbonate. e.g. corals.
? exhibit two body forms : polyp and medusa e.g., Hydra, Aurelia.
? Alternation of generation between body forms called metagenesis ocurs in
Obelia where :
           Medusa   Polyp. (Sessile and cylindrical)
    (free swimming &
       umbrella shaped)
? e.g., Physalia, Adamsia, Pennatula, Gorgonia,Meandrina.
Phylum Ctenophora :
? Also called as sea walnuts or comb jellies.
? Are exclusively marine, radially symmetrical.
? Have tissue level organisation, are diploblastic.
? Digestion both extra and intracellular.
? Body has eight external rows of ciliated comb plates for locomotion.
? Show Bioluminescence (Property of living organisms to emit light).
? Hermaphrodite (sexes are not separate).
? Only sexual reproduction occurs. Exernal fertilization. Indirect development.
e.g., Ctenoplana, Pleurobrachia.
Phylum Plathyhelminthes :
? Also called as ‘flat worms’.
? Have dorsoventrally flattened body. Are mostly endoparasites in animals.
? Are bilaterally symmetrical, triploblastic, acoelomate,with organ level of
orgnisation.
? Absorb nutrients through body surface.
? Parasitic forms have hooks and suckers.
? ‘Flame cells’ help in osmoregulation and excretion.
40
? Sexes not separate.
? Fertilisation internal. Many larval stages present. Planaria has high
regeneration capacity. e.g., Taenia, Fasciola.
Phylum Aschelminthes :
? Also called ‘round worms’.
? May be free living, parasitic, aquatic or terrestrial.
? Are bilaterally symmetrical, triploblastic, pseudocoelomate.
? Alimentary canal complete (has muscular pharynx), wastes removed through
excretory pore.
? Sexes separate. (dioecious)
? Females longer than males.
? Fertilisation internal. Development direct or indirect. e.g., Ascaris,Wuchereria,
Ancylostoma.
Phyum Annelida :
? Are aquatic or terrestrial, free-living or parasitic.
? Are bilaterally symmetrical, triploblastic, organ-system level of organisation
and metamerically segmented body.
? Are coelomate animals.
? Have longitudinal and circular muscles for locomation.
? Have closed circulatory system.
? Nereis (dioecious and aquatic annelid) has lateral appendages called parapodia
for swimming.
? Have nephridia for osmoregulation and excretion.
? Neural system consists of paired gangila connected by lateral nerves to a
double ventral nerve cord.
? Reproduction is sexual.
? e.g., Earthworm (Pheretima) and Leech (Hirudinaria) which are hermaph
rodites (i.e., monoecious).
Phylum Arthropoda :
? Largest phylum of Animalia.
? Are bilaterally symmetrical, triplobastic, segmented externally and organ
system level of organisation, coelomate.
? Body divisible into head, thorax, abdomen and has a chitinous exoskeleton.
Jointed appendages are present.
41
? Respiration by gills, book gills, book lungs or tracheal system. Excretion
through malpighian tubules.
? Sensory organs : Antennae, eyes; Organs of balance : Statocysts.
? Fertilisation usaully internal. Development is indirect or direct. Are mostly
oviparous.
 e.g., Apis, Bombyx, Laccifer, Anopheles, Culex, Aedes, Locusta, Limulus.
Phulum Mollusca :
? Second largest phylum of Animalia.
? Terrestrial or aquatic
? Are bilaterally symmetrical, triplobastic and organ system level of organisation,
coelomate.
? Body vidisble into head, muscular foot and visceral hump  and is covered
by calcareous shell and is unsegmented.
? Mantle : Soft and spongy layer of skin; Mantle cavity : Space between
visceral hump and mantle.
? Respiration and excretion by feather like gills in mantle cavity.
? Head has sensory tentacles. Radula a rasping organ for feeding in mouth.
? Are oviparous, dioecious, have indirect development.
 e.g., Plia, Pinctada, Octopus, Sepia, Loligo, Aplysia, Dentalium, Chaetopleura.
Phylum Echinodermata :
? Are spiny bodied organisms with endoskeleton of calcareous ossicles.
? Are exclusively marine, radially symmetrical in adult but bilaterally
symmetrical in larval stage. Organ system level of organisation.
? Triploblastic and coelomate.
? Digestive system complete. Mouth ventral, Anus on dorsal side.
? Food gathering, respiration, locomotion carried out by water vascular system.
? Excretory system is absent.
? Reproduction–sexual, sexes are separate.
? Fertilisation external. Development indirect (free swimming larva)
? e.g., Asterias, Cucumaria,  Antedon, Echinus, ophiura.
Phyum Hemichordata :
? Represents small group of worm-like organisms.
? Was earlier placed as sub-phylum of Phyum Chordata.