11th Class

Habitat Selaginella is commonly called the little club moss or spike moss. Selaginella is mainly found in damp shaded places. A few species are xerophytic and can withstand the dry conditions for months together. In dry conditions, the plant rolls up into a compact ball and root system is disorganized. During the rainy conditions the ball on absorbing moisture, becomes green again. Such plants are called resurrection plants or bird's nest moss, e.g., S.lepidophylla and S. pilifera are xerophytes and sold in the market as novelties, S.bryopteris (Sanjeevani) and S.rupestris (ornamental). The common epiphytic species are S. chrysocaulos, S. kraussiana, S. oregana, S. chrysorrhizos. Structure External structure : The plant body is sporophytic (2n), which is an evergreen and delicate herb having adventitious roots. The plants show great variation in their morphology. Some species are prostrate more...

(Gk. Amphi = both; bios = Life) General characters (1) Aquatic or semi aquatic (freshwater), air and water breathing, carnivorous, cold–blooded, oviparous, tetrapod vertebrates. (2) Head distinct, trunk elongated. Neck and tail may be present or absent. (3) Limbs usually 2 pairs (tetrapod), some limb less Toes 4-5 (pentadactyle) or less. Paired fins absent. Median fins, if present, without fin rays. (4) Skin soft, moist and glandular. Pigment cells (chromatophores) present. (5) Exoskeleton absent. Digits claw less. Some with concealed dermal scales. (6) Endoskeleton mostly bony. Notochord does not persist. Skull with 2 occipital condyles. i.e. Dicondylic skull. (7) Mouth large. Upper or both jaws with small homodont teeth. Tongue often protrusible. Alimentary canal terminates into cloaca. (8) Respiration by lungs, skin and mouth lining. Larvae with external gills which may persist in some aquatic adults. (9) Heart 3–chambered (2 auricles + 1 ventricle). Sinus venosus present. Aortic arches 1-3 more...

(L. avis = bird) or (Gk. ornis = bird) General Characters (1) Feather-clad, air-breathing, warm-blooded, oviparous, bipedal flying vertebrates. (2) Limbs are two pairs. Forelimbs are modified as wings for flying. Hind limbs or legs are large, and variously adapted for walking, running scratching, perching, food capturing, swimming or wading, etc. (3) Exoskeleton is epidermal and horny. (4) Skin is dry and devoid of glands except the oil or preen gland at the root of tail. (5) Pectoral muscles of flight are well developed.             (6) Skull smooth and monocondylic, bearing a single occipital condyle. Cranium large and dome-like. Sutures indistinct. (7) Vertebral column short. Centra of vertebrae heterocoelous (saddle-shaped). (8) Sternum large, usually with a vertical, mid ventral keel for attachment of large flight muscles. (9) Ribs double-headed (bicephalous) and bear posteriorly directed uncinate processes. (10) Both clavicles and single inter clavicle fused to form a V–shaped bone, called furcula more...

(L. mamma = breast) General characters (1) Hair-clad, mostly terrestrial, air-breathing, warm blooded, viviparous, tetrapod vertebrates. (2) Limbs 2 pairs, pentadactyle, each with 5 or fewer digits. Hind limbs absent in cetaceans and sirenians. (3) Exoskeleton includes lifeless, horny, epidermal hairs, spines, scales, claws, nails, hoofs, horns, bony dermal plates, etc. (4) Skin richly glandular containing sweat, sebaceous (oil) and sometimes scent glands in both the sexes. Females also have mammary glands with teats producing milk for suckling the young. (5) Endoskeleton thoroughly ossified. Skull dicondylic having 2 occipital condyles. Cranium large. A single zygomatic arch present. Pterygoids small, scale-like. Otic bones fused into periotic which forms tympanic bulla with tympanic. Each half of lower jaw made of a single bone, the dentary, articulating with squamosal of skull Vertebrae with terminal epiphyses and flat centra (acoelous). Cervical vertebrae usually 7. Ribs bicephalous. Coracoid vestigial. (6) Teeth are of several types more...

(L. reptare = to creep) General Characters (1) Predominantly terrestrial, creeping or burrowing, mostly carnivorous, air 'breathing, cold' blooded, oviparous and tetrapodal vertebrates. (2) Body bilaterally symmetrical and divisible into 4 regions-head, neck, trunk and tail. (3) Limbs 2 pairs, pentadactyle. Digits provided with horny claws. However, limbs absent in a few lizards and all snakes. (4) Exoskeleton of horny epidermal scales, shields, plates and scutes. (5) Skin dry, cornified and devoid of glands. (6) Mouth terminal. Jaws bear simple conical teeth. In turtles teeth replaced by horny beaks. (7) Alimentary canal terminates into a cloacal aperture. (8) Endoskeleton bony. Skull with one occipital condyle (monocondylar). A characteristic T-shaped inter clavicle present. (9) Heart usually 3-chambered, 4-chambered in crocodiles. Sinus venosus reduced. 2 systemic arches present. Red blood corpuscles oval and nucleated. Cold?blooded. (10) Respiration by lungs throughout life. (11) Kidney metanephric. Excretion uricotelic. (12) Brain with better development of more...

The kingdom animalia or animal kingdom is the kingdom of consumer organisms having ingestive type of nutrition. It is the largest kingdom, with 1.2 million members. It has numerous having different type of form, structure, organisation, complexity and development. General features of animals The animals possess several general features, which, taken together, distinguish them from the members of other kingdom. (1) Animals are multicellular eukaryotes and in most cases their body cells form tissues that become arranged as organs and organ systems. (2) Animals have heterotrophic mode of nutrition. They get carbon and energy by ingesting other organism or by absorbing nutrients from them. Animals may be herbivores, carnivores, omnivores, parasites, suspension feeders or deposit feeders. (3) Animals require oxygen for aerobic respiration. (4) Animals are motile, possess active movement during some stage of their life cycle. Even the sessile sponges have free swimming larval stages. (5) The animal body more...

 (L.annelus = ring, eidos = form) Brief History : Linnaeus (1758) included all soft–bodied worms in “Vermes”. Lamarck (1801) established phylum annelida for higher types of worms. General characters (1) Annelids are bilaterally symmetrical animals. (2) They have organ-system grade of organization. (3) They are coelomate (schizocoelomate) animals. (4) They have triploblastic body wall. (5) The muscle layers are thick in the body wall. Hence the body wall is said to be dermomuscular. (6) The body is divided into a numerous segments called the metameres or somites. The segmentation is known as metamerism. (7) The body is covered with a thin cuticle. (8) Locomotory organs are setae. (9) Digestive system is well developed. These have tube-within-a-tube body plan. (10) Blood vascular system is a closed type (11) Excretory system is formed of segmentally arranged nephridia. (12) These always show cutaneous or skin respiration. (13) Nervous system is formed of a more...

 (Gk. Arthron = joint; Podos = foot) Brief History : Aristotle described a few crabs and other arthropods. Linnaeus included all such animals in his group “Insecta”. Lamarck divided this group into three classes – Crustacea, Hexapoda and Arachnida. Finally, Von seibold (1845) established the phylum Arthropoda for these animals. General characters (1) Occur widely on land, in air, and in all sorts of water, from snowy tops of high mountains to the depths of ocean. Many are parasites of other animals and plants. Hence, the phylum is of great economic importance. (2) Bilateral, triploblastic, body segmented and also divided into head, thorax and abdomen. Segmentation marked only externally; number of segments or somites fixed and each has its separate exoskeleton of thick and hard,  chitinous cuticle secreted by epidermis of body wall. Head somites always fused. (3) Each segment basically bears a pair of lateral jointed appendages adapted for more...

(Gk. nema = thread; helmin = worm) Brief History : Ancient people were familiar with certain large-sized nematode parasites of domestic animals. Minute nematodes were discovered only after the invention of microscope. Linnaeus (1758) included these in “Vermes” Rudophi (1793, 1819) included these under “Nematoidea” Gegenbaur (1859) ultimately proposed “Nemathelminthes” for these. General Characters (1) Many endoparasites of various animals and plants; others free–living and widely distributed in all sorts of water and damp soil. (2) Mostly minute or small; some large (1 mm to 25 cm); some upto several meters long. (3) Slender, cylindrical, elongated body usually tapering towards both ends, and unsegmented. (4) Body wall formed of a thick, tough and shiny cuticle, a syncytial hypodermis beneath cuticle, and innermost layer of peculiar, large and longitudinally extended muscle cells arranged in four quadrants. (5) Triploblastic, bilaterally symmetrical, pseudocoelomate, false coelom derived from embryonic blastocoel, unsegmented. (6) Straight alimentary more...

General Characters (1) Aquatic, aerial or terrestrial. All free-living with no fully parasitic forms. (2) Body small to large, bilaterally symmetrical and metamerically segmented. (3) A post anal tail usually projects beyond the anus at some stage and may or may not persist in the adult. (4) Exoskeleton often present; well developed in most vertebrates. (5) Body wall triploblastic with 3 germinal layers : ectoderm, mesoderm and endoderm. (6) Coelomate animals having a true coelom, enterocoelic or schizocoelic in origin. (7) A skeletal rod, the notochord, present at some stage in life cycle. (8) A cartilaginous or bony, living and jointed endoskeleton present in the majority of members (vertebrates). (9) Pharyngeal gill slits present at some stage; may or may not be functional. (10) Digestive system complete with digestive glands. (11) Blood vascular system closed. Heart ventral with dorsal and ventral blood vessels. Hepatic portal system well developed. (12) Excretory more...