Characteristics Body Design

Level of organisatio

n

Symmetry Body Cavity

Special Features ExamplesGroups

Porifera Acoelomate Cellular Level

Radially symmetrical or asymmetrical

Absent Non-motile animals attached to some solid support. Pores all over the body, canal system circulates water to bring oxygen and food, outer cover(skeleton) very hard, mostly marine animals.Nervous system absent.

Euplectella, Sycon, Spogilla.

Coelenterata(Cnidaria)

AcoelomateDiploblastic

Tissue Level

Radially symmetrical or biradially symmetrical

True body cavity absent

Gastrovascular cavity (coelenteron) has a single exterior opening that serves as both mouth and anus. Body made of two layers of cells. Some members colonial (corals) & some solitary(Hydra)

Hydra , Jelly Fish, Sea Anemone

Platyhelminthes flat worms

acoelomateTriploblastic

Partially organ level

Bilaterally symmetrical

True body cavity absent

Some forms are free living but many are parasitic. Planarians are free living. Tape worm and Liverfluke are parasitic. Body is flattened dorsiventrally ie. From top to bottom, that is why they are called flatworms.

Planaria, Liverfluke, Tapeworm.

Nematodacylinderical worms

Triploblastic Tissue Level

Bilaterally symmetrical

False body cavity (Pseudocoelom) Present

Cylinderical body. Many nematodes are free living .Some nematodes are parasitic eg. common roundworms, which probably infest more than half the world's humans; hookworms; and filarial worms(Wuchereria), that causes filariasis (elephantiasis)

Ascaris, Wuchereria

Annelidasegmented worms

Triploblastic Organ Level

Bilaterally symmetrical

True Body cavity- COELOMATE

All members of the group are to some extent segmented, in other words, made up of segments . Segmentation is also called metamerism. Segments each contain elements of such body systems as circulatory, nervous, and excretory tracts.

Nereis, Earthworm, Leech

Arthropoda(ARTHRO means joints & PODA means legs)

Triploblastic Organ Level

Bilaterally symmetrical AND SEGMENTED

True Body cavity COELOMATE

Open Circulatory system- blood does not flow in well defined blood vessels. Coelomic cavity is blood filled and is called HEMOCOEL.

Butterfly, Housefly, Prawn, Scorpion

Mollusca Triploblastic Organ Level

Bilaterally symmetrical

True Body cavity COELOMATE

Reduced Coelomic cavity, little segmentation, Open circulatory system, Kidney like organs for excretion. Body usually divided into head, dorsal visceral mass and foot. Foot is used for movement.

Pila, Octopus, Unio, Chiton

EchinodermataEchinos (greek)=hedgehog

Triploblastic Organ Level

Radial in adults and bilateral at larval stage

True Body cavity COELOMATE

Echinos (greek)=hedgehog, derma=skin; so thses animals are called spiny skinned animals, free living and marine, They have a peculiar water driven tube system used for moving in water(Water vascular system). Hard skeleton of CaCO3

Antedon, Holothuria, Echinus, Aeterias (Starfish)

Protochordata Triploblastic Organ Level

Bilaterally symmetrical

True Body cavity COELOMATE

Notochord present at some stage of life. Mostly marine animals Balanoglossus, Herdemania

Chordata Triploblastic Organ Level

Bilaterally symmetrical

True Body cavity COELOMATE

Presence of notochord, single, dorsal, hollow nerve cord,paired gill pouches, post anal tail at some stage of life. ventral heart,complete digestive system.

Fish, Man, Birds etc.

Phylums of Animal Kingdom