Updated by: Arabinda Naik
1. Anamniotes. Vertebrates without embryonic membranes. e.g., fishes, amphibians. Amniotes. Vertebrates with embryonic membranes (chorion amnion, allantois, yolk sac), e.g., reptiles, birds, mammals.
2. Acrania or Protochordates. Chordates without cranium (brain box). It includes Urochordata and cephalochordate.
3. Chordates. Animals with notochord. All urochordates, cephalochordates and vertebrates are called chordates.
4. Craniate or Vertebrata. Chordates with cranium. It includes cyclostomes, Pisces, amphibians, reptiles, birds, and mammals.
5. Non chordates Animals without notochord (a rod like elastic structure which sup- ports the body). Phylum Porifera to phylum Hemichordate are called non chordates.
6. Invertebrates. Animals without vertebral column (backbone). All the non-chordates, urochordates and cephalochordates are collectively called invertebrates.
7. Habitat. The habitat of an organism is the place where it lives. Animals have two major types of habitats, aquatic and terrestrial.
8. Aquatic Animals. They live in water. Animals of sea water are called marine animals. Animals of rivers, streams, lakes, ponds and even drains are called freshwater animals. Animals which live in between salty and fresh water are called brackish water animals. Brakish water has less salt content than that of ocean.
9. Zooplankton The aggregate of passively floating or drifting animals in a body of water is called zooplankton e.g., many protozoan protists, small crustaceans (arthropods) and various invertebrate larvae.
10. Nanoplankton These are too small to be caught in a plankton net. organisms in a body of water able to move independently of water currents is called nekton, e.g., sharks, bony fish, etc. Coral reefs provide the best habitat for marine animals. Benthic Animals These animals live at the bottom of lakes, oceans, and seas, e.g., star fishes, sea cucumbers, sponges, corals, etc.
11. Littoral Animals These animals live near the seashore.
12. Neritic Animals The animals which live in the shallow waters of sea, less than 200 metres deep are called neritic animals.
13. Lentic Animals. These animals live in stagnant water body such as ponds. lakes, etc.
14. Lotic Animals. These animals live in running water such as streams. rivers, etc.
15. Neuston A collective term used for minute organisms which rest on the surface of water.
16. Anadromous fishes. These marine fishes migrate from the sea into the estuaries for spawning, e.g., Hilsa.
17. Catadromous fishes. These fishes migrate from estuaries to sea for spawning, e.g., Anguilla (eel).
18. Euryhaline Animals. These animals have a wide salinity tolerance, e.g., marine animals.
19. Stenohaline Animals. These animals have only a narrow range of salinity tolerance and hence remain restricted to either fresh water or salt water.
20. Stenothermal Animals. These animals can tolerate a narrow range of variation in temperature.
21. Eurythermal Animals. These animals tolerate a wide range of variation in temperature. e.g., Blahseers.
22. Terrestrial Animals. They live on land and are of different kinds.
23. Cursorial Animals. They run fast. e.g., kangaroo. dog. horse, etc.
24. Fossorial Animals. They live in burrows/underground. e.g., earthworm. rabbit, etc. Arboreal animals. They live on the trees. e.g., bats, monkeys. etc.
25. Scansorial Animals. they climb walls, etc., e.g., wall lizard. flying squirrel, etc.
26. Volant or Aerial or flying Animals. 'They can fly, e.g., winged insects, birds, bats, etc.
27. Habits. Habit refers to nature of the animals.
28. Solitary Animals live alone, e.g., Tapeworm, grasshopper.
29. Colonial Animals live in groups and help one another and thus show social life, e.g., honeybees. termites. asps and ants.
30. Gregarious Animals live in groups but do not help one another, e.g., locust.
31. Free Living Animals lead an independent life, e.g., horse. dog, etc.
32. Parasitic Animals depend on other animals for food, protection, etc.
33. Sessile or Sedentary Animals are fixed to the substratum. e.g. sponges.
34. Coprophagous Animals eat their faecal matter. e.g., rabbit.
35. Sanguivores feed on blood. e.g. leech, bed bug.
36. Saprophagous Animals feed on all sorts of fluids or semifluid organic matter, e.g., housefly.
37. Cannibals eat their fellows, e.g., cockroach. bed bug.
38. Planktivorous feed on plankton, e.g., young one of Labeo (Rohu fish). whale.
39. Piscivorous feed on fishes. e.g., some aquatic birds.
40. Detritivorous feed on dead material, e.g., vulture.
41. Herbivorous feed on plants. e.g. deer.
42. Carnivorous Animals feed on animals, e.g., lion.
43. Omnivorous Animals feed on all kind of food. e.g., man.
44. Larvaevorous Animals feed on larvae, e.g., Gambusia (mosquito fish).
45. Grainivorous Animals feed on grains, e.g., pigeon.
46. Folivorous Animals eat leaves, e.g., sheep, goats.
47. Polygamous Animals live in the company of more than one sexual partner. e.g., deer. zebra, etc. (a) Polyandrous Animals— a female mates with more than one male. (b) Polygynous Animals— a male mates with more than one female.
48. Monogamous Animals have only one sexual partner.
49. Monoecious or Hermaphrodite or Bisexual Animals are the animals in which both male and female sex organs are found in one individual. e.g., Tapeworm. liver fluke, earth- worm, leech, etc.
50. Dioecious or Unisexual Animals are the animals which have only either male or female sex organs. e.g., most of animals.
51. Protandrous Animals are the animals in which male sex organs mature earlier than the female sex organs. e.g., earthworm.
52. Protogynous Animals are the animals in which female sex organs mature earlier than male sex organs. e.g., Herdmania.
53. Oviparous Animals lay eggs, e.g., frog. birds, egg laying mammals.
54. Ovoviviparous Animals are the animals which give birth to young ones without placenta formation. e.g., shark. viper.
55. Viviparous Animals give birth to the young ones with placenta formation, e.g. rabbit, human beings. etc.
56. Poikilothermal or Ectothermic or Cold-Blooded Animals are those animals in which body temperature varies according to the surrounding environment. e.g., all invertebrates. fishes, amphibians, and reptiles.
57. Homoiothermal or Endothermic or Warm-Blooded Animals are those animals in which body temperature remains constant and does not change with the change of environmental temperature, e.g. birds and mammals.
58. Nocturnal Animals like darkness, e.g., Owl.
59. Diurnal Animals are active during day. e.g., man, horse, etc.
60. Crepuscular Animals move about in twilight. e.g., rabbit.
61. Frugivorous Animals feed on fruits. e.g. parrot.
62. Coprozoic Animals feed on dung, e.g., pig
63. Vespertine Animals are active during evening or dusk, e.g. small insectivorous bats.
64. Saltatorial Animals are the animals whose hindlegs are long and modified for jumping. e. g., locust, grasshoppers, and crickets.
65. Auroral Animals are active during dawn.
66. Cave Dwellers live in caves, e.g., Proteus.
67. Epilithic Animals adhere to rocks or stones.
68. Epiphytic Animals get attached to the surface of plants.
69. Epizoons are those animals which live on the body of other animals.
70. Mimicry. It is the resemblance of one organism to another or to any natural object for the purpose of concealment, protection or for some other advantage.
71. Crypsis. It is a type of colouration in which an animal helps to camouflage in its natural environment.
72. Autotomy. Self-mutilation of a part of the body is called autotomy. It is observed in legs of prawn and in tail of wall lizard.
73. Regeneration. Regeneration involves (l) Epimorphallaxis — restoration of lost part and (2) Morphallaxis— reconstruction of whole body from a small part of the organism's body.
74. Hibernation. Winter sleep. It is observed in frogs, many reptiles, and some mammals during winter season.
75. Aestivation. Summer sleep. It is observed in frogs during too much heat.
76. Parthenogenesis. Development of an egg (ovum) into a complete individual without fertilization by a sperm is known as parthenogenesis. Drones (males) of honeybees are formed by parthenogenesis.
77. Paedogenesis. When parthenogenesis occurs in larva it is called paedogenesis. It occurs in sporocyst and redia larvae of liver fluke.
78. Neoteny. When the larva retains adult characters such as gonads and starts producing young ones by sexual reproduction it is called neoteny. It occurs in the axolotl (larva of Ambystoma— tiger salamander).
79. Metachrosis. Frogs can change their skin colour according to the colour of their external environment. This capability is called metachrosis.
80. Pachyderms (i.e., thick skinned). Elephants are pachyderms.
81. Levels of Organisation. Four levels of organization are found in animals.
82. Cellular Level. The body consists of many cells which may be similar or show minor division of labour e g., sponges.
83. Tissue Level. The cells form poorly defined tissues, e.g. Cnidarians.
84. organ Level. Tissues are grouped together to form organs. e.g. Platyhelminthes. organ-System Level. The cells are organised into tissues, tissues into organs and organs into organ systems, e g.. Aschelminths to chordates.
85. Protostomes. The mouth of the digestive tract develops first in the embryo and anus is formed later. This occurs in flat worms, roundworms, annelids, molluscs, and arthropods. The animals which have this body plan are called protostomes.
86. Deuterostomes. The anus of the digestive tract develops first in the embryo and the mouth is formed later. This is seen in echinoderms, hemichordates, and chordates. Thus, chordates are evolutionarily closer to the echinoderms. The animals which possess this body plan are called deuterostomes.
87. Radial Symmetry. In this type of symmetry, the body of the individual can be divided into equal halves by any plane passing through the centre from top to bottom. This of symmetry is found in some sponges (Sycon), cnidarians echinoderms (e.g. star fish). When the body can be divided into two similar halves by one or two vertical planes only, the radial symmetry is called biradial symmetry. It is present in the sea anemones.
88. Bilateral Symmetry. In this type of symmetry, the body can be divided into two equal halves by a single plane only the important body organs are paired and occur on the two sides of a central axis. Bilateral symmetry is found in many invertebrates and all vertebrates.
89. The right and left sides of the body are called the lateral sides. The side of the body which is kept forward during locomotion is termed the anterior side and the opposite one is called posterior side. The back or upper surface is termed dorsal and the under surface (towards the substratum) is called ventral.
90. The part of a tissue. organ. etc. that is nearest to the of attachment or origin is known as proximal end. For example. Upper arm is proximal end of the forelimb. The part of a tissue. organ, limb, etc. that is farther away from the point of attachment or origin is called distal end. For example. the fingers are at the distal end of the fore limb.
91. Diploblastic and Triploblastic Animals. The embryos of porifera and cnidarians have two germinal layers. the ectoderm and endoderm. These animals are called diploblastic. An undifferentiated layer, mesoglea, is present in between the ectoderm and endoderm. The embryos of all other animals (from phylum Platyhelminthes to phylum Chordata) have three germinal layers— the ectoderm, mesoderm, and endoderm. These animals are called triploblastic animals. The germinal layers form the body of the animals.
92. Segmentation. Segmentation is division or differentiation of the body into distinct portions called segments. It is of two types: metameric segmentation and pseudo-metamerism.
93. Metameric Segmentation (True metamerism or True segmentation). It is a type of segmentation where external divisions correspond to internal divisions. It occurs in three highly organized phyla — Annelida. Arthropoda and Chordata. The body is often divided both externally and internally into several segments (metameres) e.g., annelids. Seg- mentation is mostly external in arthropods and mainly internal in man and other chordates (vertebrae, body muscles. some blood vessels and nerves).
94. Pseudo metamerism (False segmentation). It is found in tapeworms. The pro- glottides (segments of tapeworms) are budded off from the neck and are not of embryonic origin hence, this segmentation is called pseudo metamerism. Pseudo- segmentation as found in tapeworms is external only. The body is not internally divided.
95. Cephalization. Differentiation of a definite head at the anterior end is termed the cephalization. There is a concentration of sense organs, nervous tissue (brain) and food catching organs at the anterior end.
96. Appendages. Projecting parts from the body of an animal that serve in locomotion, feeding and other ways are called appendages. They include tentacles of cnidarians, minute setae and parapodia of many annelids, antennae, legs and wings of arthropods, foot of molluscs and fins. legs and wings of vertebrates.
97. Sexual Dimorphism. When the male and female animals can be distinguished externally, the condition is called sexual dimorphism. The latter is seen in male and female frogs, peacock, and peahen. lion and lioness and human beings. Fertilization. Fertilization is the union of male and female gametes. In animals. male gametes or sperms are motile. The female gametes or ova are nonmotile.
98. When fertilization occurs outside the body of the female. it is called external fertilization, e.g. Starfish. Frog.
99. In many cases, fertilization takes place in the genital tract of the female. It is known as internal fertilization, e.g. reptiles, birds, mammals.
100. When the fusion of male and female gametes of the same parent takes place, it is called self-fertilization, e.g., tapeworm.
101. When the fusion of male and female gametes of different parents takes place. it is known as cross fertilization, e.g., all fishes. amphibians, reptiles.
102. Development. Development includes changes that an organism undergoes from its beginning to maturity. It is of two types. direct and indirect. In direct development. the young ones resemble the adults in all respects except colour. size. There is no intermediate stage in direct development, e.g. Hydra, earthworm, and silver fish (insect). In indirect development. the young ones do not resemble the adults. The young ones usually pass through one or more intermediate stages before obtaining the shape of the adults. The phenomenon of passing through different juvenile stages before attaining the form of adult is known as metamorphosis, e.g., silk moth.
103. Embryo. It is an organism in early stages of development. In human beings it is from conception (act of becoming pregnant) to end of 8th week.
104. Foetus. Unborn young one of a viviparous animal is called foetus. In human beings an embryo is called foetus from end of 8th week till birth.
105. Acoelomates. The animals which do not have coelom are called acoelomates e.g. sponges, cnidarians, ctenophores, and flat worms.
106. Pseudocoelomates, The Mesoderm is present as scattered pouches in between the ectoderm and endoderm. Such a body cavity is called pseudocoelom and animals possessing them are called pseudocoelomates. Round worms are pseudocoelomates.
107. Eucoelomates (Coelomates). The animals which possess true coelom are called eucoelomates or coelomates. The true coelom is a body cavity which arises as a cavity in embryonic mesoderm. In this case, the mesoderm of the embryo provides a cellular lining, called coelomic epithelium or peritoneum, to the cavity. The coelom is filled with coelomic fluid secreted by the peritoneum. True coelom is found in annelids, echinoderms, and chordates. True coelom is of two types: schizocoelom (schizocoel) and enterocoelom (enterocoel).
108. Schizocoelom. It develops as a split in the mesoderm sheet. It is found in annelids, arthropods, molluscs.
109. Enterocoelom. The mesoderm arises from the wall of the embryonic gut or enteron as hollow outgrowths which form this type of coelom. It occurs in echinoderms and chordates. The cavity filled with blood is called haemocoel. It is found in arthropods and molluscs.
110. Digestive Tract. Digestivc tract is the passage where food is taken for digestion, absorption, and elimination of undigested food. Cnidarians and flat worms have a digestive tract with a single opening termed mouth that takes food as well as eliminates the undigested food. This type of digestive tract is called incomplete. Digestive tract of many animals has two openings: mouth for intake of food and anus for the elimination of faecal matter. Such a digestive tract is termed complete. It is found from round worms to mammals.
111. Digestion. Digestion is the breaking down of complex organic food molecules into simpler organic molecules by hydrolysis. Digestion is of two types: intracellular digestion and extracellular digestion.
112. Heterotrophic mode of Nutrition. Heterotroph is an organism that cannot use inorganic materials to synthesize the organic compounds needed for growth but obtains them by feeding on other organisms or their products. Examples: Carnivore, herbivore, omnivore, parasite, scavenger, or saprophyte (All animals, fungi and most bacteria are heterotrophs). The nutrition is called heterotrophic nutrition.
113. Active Movement. As compared to members of other kingdoms, animals perform more rapid and complex way of movement. Movement of animals is due to the flexibility of their cells, which is perhaps the most characteristic feature of the animals. Some animals can swim (e.g., jelly fish, squids, fishes, whales, etc), some can fly (e.g., butterflies, birds, bats) and others can run or walk on land (e.g., horses, cattle, tigers, lions, men, etc.)
114. Blood Vascular System. It is a system that takes part in continuous flow of blood in the body. Blood is not present in porifera, cnidaria, Ctenophora, Platyhelminthes and aschelminths (nemathelminths). Blood vascular system is of two types, closed and open. (i) In closed the blood circulates inside the blood vessels without ever coming in direct contact with the body cells, e.g., annelids, chordates. (ii) In open type the blood flows in open spaces.
115. Respiration (Exchange of Gases). Aerobic animals utilize oxygen which is obtained from air or water. Certain aquatic animals like Hydra take oxygen and give up carbon dioxide through body surface. This is termed body-surface respiration. Many animals such as prawn, unio, fish have gills for exchange of gases. This type of respiration is called branchial respiration. In earthworm, leech, frog, etc., exchange of gases takes place through skin, this is termed as cutaneous respiration. In insects and other arthropods, there are present tubular structures, the tracheae for exchange of gases, this is called tracheal respiration. In arachnids (e.g., spiders) exchange of gases takes place through book-like structures, the Book gills are respiratory organs in king crabs.
116. Lungs are meant for exchange of gases in many animals (e.g., amphibians, reptiles, birds, mammals). This type of respiration is termed pulmonary respiration. In certain animals like frogs and toads exchange of gases also takes place through the epithelial lining of the buccopharyngeal cavity. This is called buccopharyngeal respiration. The frogs have three modes of respiration namely cutaneous, buccopharyngeal and pulmonary. Lung fishes respire through both gills and lungs. Anaerobic respiration (in absence of oxygen) occurs in various parasitic animals.
117. Excretion. Excretion is the removal of the metabolic wastes from the body. Sponges. cnidarians, ctenophores, and echinoderms lose wastes by diffusion through body surface. Many animals have definite excretory structures. The flat worms have flame cells as excretory structures. In Ascaris (round worn)), 'H' shaped excretory system of canals and complicated giant cell called Renette cell is present. Annelids have nephridia as excretory organs and crustaceans such as prawn contain untennary (green) glands in the antennae as excretory organs. Insects and. some other arthropods have Malpighian tubules as excretory organs. Molluscs and vertebrates have kidneys as excretory organs. Excretory organs not only remove metabolic wastes but also maintain water and salt content in the body (osmoregulation).
118. Ammoniotelic Animals. They excrete ammonia. Examples: protozoans (e.g., Amoeba, Paramecium, sycon. cnidarians or coelenterates (e.g., Hydra), sponges (e.g., Liver nuke, Tape worn), Ascaris. Nereis. Earthworm. Leech. Prawn. Pila. Bony fish (e.g., labeo). Amphibian tadpoles. tailed amphibians (e.g., Salamanders). Crocodiles.
119. Ureotelic Animals. They excrete urea. Examples: Cartilaginous fishes (e.g., Sharks and Rays). semi-aquatic amphibians (e.g., frogs and toads), turtles. alligators. mammals including man. Ascaris and Earthworm are both ammoniotelic and ureotelic.
120. Uricotelic Animals. They excrete uric acid. Examples: Most insects, some land commonly known as wood louse), land snails land reptiles (lizards and snakes), birds.
121. Aminotelic Animals. They excrete excess amino acids. Examples: Some molluscs (e.g., Limnaea. unio). some echinoderms; (e.g. Asterias— star fish).
122. The central neural system comprises the brain and spinal cord. The brain is situated in the cranium (brain box) of the skull and the spinal cord lies in the neural canal of the vertebral column (back bone).
123. The nerves which arise from the central neural system constitute the peripheral neural system. The latter includes the cranial nerves arising from the brain and the spinal nerves originating from the spinal cord. The autonomic neural system comprises the sympathetic and parasympathetic neural systems.
124. Receptors. A receptor is a sensory cell or organ which receives stimuli (changes in the from outside or inside the animal and passes impulses to the neural system. The receptors are always connected with the central neural system by means of sensory nerve fibres. Different types of receptors such as eyes, ear, skin etc. are found in various animals.
125. Endocrine glands. These glands are also called ductless glands. Their secretions are known as hormones. The latter are mostly transported by blood from the endocrine glands to the target cells or organs for their physiological activity.
126. Skeleton. Hard external or internal structures of animal body constitute the skeleton. Skeleton supports and protects soft parts of the body. It is of two types: exoskeleton and endoskeleton. Exoskeleton lies outside the body of an animal and is made up of non-living materials. Examples of exoskeleton are chitinous cuticle of arthropods. calcareous shell of molluscs, and scales, feathers, hair, horns, hoofs, claws, nails, and hair of vertebrates. Endoskeleton lies entirely within the body of the animal. In vertebrates. it is composed of living hard connective tissues. namely cartilages and bones. In invertebrates such as sponges it is made up of calcareous and siliceous spicules. In some echinoderms (e.g., star fish) calcareous plates, the ossicles, which form the endoskeleton, are found in the dermis of the body wall.