The Animal Kingdom

What is the Animal Kingdom?

The kingdom consisting of multicellular eukaryotic heterotrophic organisms whose cells lack cell walls

What are the major criteria used for animal classification?

Level of organisation symmetry germ layers body cavity or coelom segmentation and presence or absence of a notochord

What are the levels of organisation in animals?

Cellular tissue organ and organ-system levels

What is cellular level of organisation?

Cells are arranged loosely and perform different functions

Which phylum shows cellular level of organisation?

Porifera

What is tissue level of organisation?

Similar cells are grouped into tissues that perform specific functions

Which phyla show tissue level of organisation?

Cnidaria and Ctenophora

What is organ level of organisation?

Different tissues are organised into organs

Which phylum shows organ level of organisation?

Platyhelminthes

What is organ-system level of organisation?

Organs work together as systems performing specialised functions

What is symmetry?

The arrangement of body parts around a central axis or plane

What is asymmetry?

An animal cannot be divided into two equal halves by any plane passing through its centre

Which major phylum is generally asymmetrical?

Porifera

What is radial symmetry?

Any plane passing through the central axis divides the body into similar halves

Which phyla show radial symmetry?

Cnidaria Ctenophora and adult Echinodermata

What is bilateral symmetry?

Only one plane divides the body into two equal right and left halves

Which animals are generally bilaterally symmetrical?

Animals from Platyhelminthes onwards except adult echinoderms

What is diploblastic organisation?

Development from two embryonic germ layers called ectoderm and endoderm

Which phyla are diploblastic?

Cnidaria and Ctenophora

What is triploblastic organisation?

Development from three embryonic germ layers called ectoderm mesoderm and endoderm

Which animals are triploblastic?

Animals from Platyhelminthes onwards

What is a coelom?

A fluid-filled body cavity between the body wall and digestive tract that is lined by mesoderm

What is an acoelomate?

An animal without a body cavity or coelom

Which phylum is acoelomate?

Platyhelminthes

What is a pseudocoelom?

A body cavity that is not completely lined by mesoderm

What is a pseudocoelomate?

An animal possessing a pseudocoelom

Which phylum is pseudocoelomate?

Aschelminthes or Nematoda

What is a true coelom?

A body cavity completely lined by mesoderm

Which major groups are coelomates?

Annelida onwards including Arthropoda Mollusca Echinodermata Hemichordata and Chordata

What is metamerism?

The division of the body into repeated segments

Which phylum is characteristically metamerically segmented?

Annelida

What is a notochord?

A rod-like structure of mesodermal origin that provides skeletal support in chordates

What are the four basic chordate characteristics?

Notochord dorsal hollow nerve cord pharyngeal gill slits and post-anal tail

What is the basic difference between chordates and non-chordates?

Chordates possess a notochord during at least some stage of development whereas non-chordates do not

What are the major non-chordate phyla in NCERT?

Porifera Cnidaria Ctenophora Platyhelminthes Aschelminthes Annelida Arthropoda Mollusca Echinodermata and Hemichordata

What are the three major chordate groups?

Urochordata Cephalochordata and Vertebrata

What is the general body organisation of Porifera?

Cellular level of organisation

What type of symmetry is found in Porifera?

Mostly asymmetrical

What is characteristic of the body of sponges?

A system of pores and canals through which water circulates

What are ostia?

Small pores through which water enters a sponge

What is the osculum?

The opening through which water leaves a sponge

What is spongocoel?

The central cavity of a sponge through which water flows

What are choanocytes?

Flagellated collar cells that create water currents and help capture food

What is the skeleton of Porifera made of?

Spicules or spongin fibres

How do sponges reproduce?

Both asexually and sexually

What is a common asexual method of reproduction in Porifera?

Budding

What are examples of Porifera?

Sycon Spongilla and Euspongia

What is the general organisation of Cnidaria?

Tissue level of organisation

What symmetry occurs in Cnidaria?

Radial symmetry

Are cnidarians diploblastic or triploblastic?

Diploblastic

What is the body cavity of cnidarians called?

Gastrovascular cavity or coelenteron

What are cnidoblasts or cnidocytes?

Specialised stinging cells characteristic of Cnidaria

What are nematocysts?

Stinging structures contained within cnidocytes

What are the functions of cnidocytes?

Defence and capturing prey

What are the two basic body forms in Cnidaria?

Polyp and medusa

What is a polyp?

A sessile cylindrical form such as Hydra

What is a medusa?

A free-swimming umbrella-shaped form such as Aurelia

What is metagenesis?

Alternation between asexual polyp and sexual medusa forms in certain cnidarians

What are examples of Cnidaria?

Hydra Obelia Aurelia Physalia Adamsia Pennatula Gorgonia and Meandrina

What are corals?

Marine cnidarians that secrete calcium carbonate skeletons

What is the general organisation of Ctenophora?

Tissue level of organisation

What symmetry occurs in Ctenophora?

Radial symmetry

Are ctenophores diploblastic?

Yes

What is a distinctive feature of Ctenophora?

Eight rows of comb plates used for locomotion

What are comb plates?

Rows of fused cilia used for locomotion

What is bioluminescence?

Production of light by living organisms

Are ctenophores bioluminescent?

Yes

What are examples of Ctenophora?

Pleurobrachia and Ctenoplana

What is the general organisation of Platyhelminthes?

Organ level of organisation

What symmetry occurs in Platyhelminthes?

Bilateral symmetry

Are platyhelminths diploblastic or triploblastic?

Triploblastic

Are platyhelminths coelomate?

No they are acoelomate

What are platyhelminths commonly called?

Flatworms

Are many platyhelminths parasitic?

Yes

What are flame cells?

Specialised excretory cells that help in osmoregulation and excretion

What are examples of Platyhelminthes?

Taenia Fasciola and Planaria

What is Taenia?

A parasitic tapeworm

What is Fasciola?

A parasitic fluke

What is Planaria?

A free-living flatworm

What is the general organisation of Aschelminthes or Nematoda?

Organ-system level of organisation

What symmetry occurs in Nematoda?

Bilateral symmetry

Are nematodes triploblastic?

Yes

Are nematodes pseudocoelomates?

Yes

What are nematodes commonly called?

Roundworms

Are nematodes free-living or parasitic?

They may be free-living or parasitic

Are sexes separate in many nematodes?

Yes many are dioecious

What are examples of Nematoda?

Ascaris Wuchereria and Ancylostoma

What disease is associated with Wuchereria?

Filariasis

What disease is associated with Ancylostoma?

Hookworm infection

What is the general organisation of Annelida?

Organ-system level of organisation

What symmetry occurs in Annelida?

Bilateral symmetry

Are annelids triploblastic?

Yes

Are annelids coelomates?

Yes