Ch 4Kingdom Animalia — Class 11 Biology, concept-first.

Animals show enormous diversity, and biologists use several structural yardsticks to bring order to this diversity and place species into a natural classification scheme.

Apart from symmetry and body cavity, animals also differ in how their body is fundamentally organised as a working whole.

In the cell aggregate plan, the body is not built up into true tissues or organs. Cells are present but show minimal division of labour and cooperate only loosely, so the body behaves more like a colo…

In the blind sac body plan, the body is essentially a sac with only one opening to the outside. Digestion takes place inside this single cavity, and both the intake of food (ingestion) and the removal…

In the tube within tube body plan, the digestive system is a tube running through the body cavity, with the mouth and anus located at two separate ends.

Building on the classification criteria and body plans described above, the animal kingdom is organised into a series of phyla — starting with the simplest sponges and ending with the most advanced ve…

Phylum Porifera (Latin porus = pore, ferre = to bear) includes the sponges — examples include Scypha, Euspongia (bath sponge) and Euplectella (Venus' flower basket).

Phylum Cnidaria includes animals such as Hydra, Aurelia (jellyfish), Physalia (Portuguese man-of-war), Adamsia (sea anemone), Diploria (brain coral) and Gorgonia (sea fan).

Phylum Ctenophora includes animals such as Pleurobrachia and Ctenoplana, commonly called comb jellies or sea walnuts. They are exclusively marine, free-swimming animals.

Phylum Platyhelminthes (Greek platy = flat, helminth = worm) includes animals such as Planaria, Taenia (tapeworm) and Fasciola (liver fluke).

Phylum Aschelminthes (Greek ascus = sac, helminth = worm), also called Nemathelminthes (nema = thread), includes animals such as Ascaris (roundworm), Wuchereria (filarial worm) and Ancylostoma (hookwo…

Phylum Annelida (Latin annulus = ring) includes animals such as Nereis, Pheretima (earthworm) and Hirudinaria (leech), and its members are commonly called ring worms or segmented worms.

Phylum Arthropoda (Greek arthron = joint, podos = leg) includes animals such as cockroach, butterfly, scorpion, millipede and prawn.

Phylum Mollusca (Latin mollis = soft) includes animals such as Pila, bivalves, Octopus (devil fish), Sepia (cuttlefish), Chaetopleura (chiton), Pinctada (pearl oyster), Loligo (squid), Aplysia (sea ha…

Phylum Echinodermata (Greek echinus = spine, derma = skin) includes animals such as Asterias (sea star), Cucumaria (sea cucumber), Echinus (sea urchin), Antedon (sea lily) and Ophiothrix (brittle star…

Phylum Hemichordata (Greek hemi = half, referring to a once-suspected link to Chordata) includes animals such as Balanoglossus and Saccoglossus.

Phylum Chordata is defined by four features present at least during early embryonic development: a flexible, cartilaginous notochord; gill slits in the pharyngeal (neck) region; a hollow, dorsal nerve…

Subphylum Urochordata (or Tunicata) includes animals such as Herdmania, Salpa and Doliolum, commonly called tunicates or ascidians. They are exclusively marine.

Subphylum Cephalochordata includes Branchiostoma (commonly called Amphioxus or lancelet). These animals are exclusively marine, small, fish-like in shape, and rarely exceed about 5 cm in length.

Subphylum Vertebrata includes all chordates in which the embryonic notochord is later replaced by a cartilaginous or bony vertebral column, which gives the group its name and provides much stronger in…

Division Agnathostomata includes the most primitive living vertebrates — animals without jaws. Among living vertebrates, it contains only one class, Cyclostomata (Greek cyclos = circular, stoma = mout…

Superclass Pisces includes the true fishes — aquatic, gill-breathing vertebrates with fins. They are poikilothermic ('cold-blooded'), meaning their body temperature varies with the surrounding water t…

Class Chondrichthyes (Greek chondron = cartilage, ichthyes = fish) includes animals such as Scoliodon (dog fish), Pristis (sawfish), electric ray, common skate, hammer-headed shark, Carcharodon (great…

Class Osteichthyes (Greek osteon = bone, ichthyes = fish) includes animals such as Bombay duck, lungfishes (Protopterus, Lepidosiren), Exocoetus (flying fish), Hippocampus (sea horse), pomfret, Labeo…

Superclass Tetrapoda includes all vertebrates that typically bear two pairs of limbs (though some, like snakes, have secondarily lost their limbs through evolution).

Class Amphibia (Greek amphi = both, bios = life) includes animals such as Rana (frog), Bufo (toad), Salamandra (salamander), Ichthyophis (a limbless amphibian) and Hyla (tree frog).

Class Reptilia (Latin repere = to creep or crawl) includes animals such as Naja naja (cobra), Hemidactylus (wall lizard), Chelonia (turtle), Crocodilus (crocodile), Testudo (tortoise), chameleon (tree…

Class Aves (Latin avis = bird) includes animals such as Columba (pigeon), Psittacula (parrot), and flightless birds like Struthio (ostrich), Kiwi and Aptenodytes (penguin), as well as Corvus (crow), N…

Class Mammalia (Latin mammae = breasts/nipples) includes animals such as bat, Rattus (rat), Macaca (monkey), Camelus (camel), whale, human beings, Cannis (dog), Felis (cat), Elephas (elephant), Equus…