1. Aboral : It means located away from or on opposite side of the body in the mouth.
  2. Acnidaria – Hydra, jelly fish
  3. Adoral : It means located on the same body surface as mouth.
  4. Aerial animal : Some animals that can fly in the air are called aerial animals.
  5. Agamete : It is a reproductive body found in mesozoa. It divides by a form of cleavage to produce a daughter individual within the body of the parent.
  6. Amphiblastula : It refers to flagellated larva found in porifera.
  7. Animals : A major group of living organisms distinguished from plants (algae, bacteria, fungi and viruses) in having the cell wall either absent of composed of nitrogeneous material. About 1-3 million described species are classified into nonchordates (no backbone) and chrodates (having backbone). Nonchrodates are further divided into various phyla.
  8. Aquatic animals : The animals which live in water are called aquatic animals.
  9. Benthos : Those forms which remain attached to stones or some other under water objects are called banthos.
  10. Bipinnaria larva : It is the larval form found in asteroid echinoderms. It is derived from auricularia but it differs from this in being stronger, more complicated development of ciliated bands.
  11. Biramous : Having two branches.
  12. Blasiochel : It is fluid filled cavity. It is also referred to as the Segmentation.
  13. Cavity : That appears at the early stage in embryonic development as the internal space within the blastula.
  14. Choanocyte : It is a flagellated collar cell found as a lining of the internal cavities of the Porifera.
  15. Coelom : Body cavity bounded externally by parietal of peritoneum and internally by visceral layer of peritoneum is called coelon.
  16. Colonial animals : If more than one individual become associated and live in groups such animals are called colonial animals.
  17. Commensalism : It is an association when two members neither benefit nor harm each other.
  18. Dectylozoid : It refers to protective or defensive polyp found in certain colonial coelenterate.
  19. Diploblastic Animals : The animals which develop from two germinal layers are called diploblastic animals.
  20. External fertilization : The fusion of gamatic cells occurs outside the body and is known as external fertilization.
  21. Fussorial animal : Some animals live in the burrows; and are called fussorial animals.
  22. Gonopore : External apertures of a gonadial duct.
  23. Gonotheca : It is a cylindrical capsule that encloses the reproductive polyp in certain colonial coelenterate.
  24. Gonozoid : It refers to the reproductive polyp found in certain colonial coelenterate.
  25. Haemocoel : The cavity which contains blood is called haemocoelom or haemocoel .
  26. Internal fertilization : The fusion of gametes which occurs inside the body is called internal fertilization.
  27. Major Phyla : Porifera sponges, spongilla (5000).
  28. Marine animals : The animals which live in sea water are termed marine animals.
  29. Mesogloea : It is the layer in the body wall of coelenterate, that lies between the epidemis and the gastrodermis (endodermis).
  30. Metamorphosis : The sum of changes which convert larva into an adult are called metamorphosis.
  31. Multicellular animal : The body of an animal is made up of a large number of cells; they are called multicellular animals.
  32. Nacreous : An iridescent near inner surface of some bivalve shells.
  33. Nauplusis : It is the earliest larval stage in crustacean. It is ovoid in shape, unsegmented but having three pairs of appendages.
  34. Nematocyst : It is the stinging cell found on the tentacles and mesenteries of coelenterates.
  35. Oocyst : It is an encysted zygote formed by the fusion of gametes in certain parasitic protozoa.
  36. Ootype : It refers to the specialized part of the oviduct that secretes the shell around the fertilized egg in digenean platyhelminthes.
  37. Ophiopluteus larva : It is a larval form which resembles the echinopluteus but differs from them in having fewer arms.
  38. Osphraduim : It refers to sense organs present in certain mollusca. It may be used for detecting sediment in water or may also be chemosensory.
  39. Ossicles : Calcareous plates that form a skeletal system in the body wall of animals like echinoderms. The plates are closely packed but do not unite to form a continuous shell.
  40. Ostium : It refers to an opening generally used for perforations in wall of the heart through which blood passes from pericardial sinus.
  41. Oviparous : The animals which lay eggs.
  42. Ovoviviparous : The fertilization is internal, animals give birth to young ones.
  43. Parasitism : It is an association in which one individual (parasite) lives at the expense of other animal (host).
  44. Pelagic : The free swimming aquatic forms are called pelagic.
  45. Pericardium : It refers to the cavity wherein the heart is located.
  46. Perioral : Means surrounding the mouth.
  47. Perisare : It refers to the horny layer that covers the stem of various colonial coelenterate.
  48. Peristome : It is a membrane surrounding the mouth.
  49. Phasmid : It refers to small, pit like sensory structure located in the tail region of certain nematode.
  50. Pinacocyte : It refers to a flattened cell that forms a covering layer in the body walls of sponges. Since such cells are capable of changing their shapes so they act as a pavement epithelium.
  51. Plankton : The aquatic forms which are drifted passively by water currents are called plankton.
  52. Planula larva : These are free swimming larva found in coelenterate.
  53. Pleopod : It refers to abdominal appendages, found in various crustacean, which are adapted for swimming.
  54. Pneumatophore : They are bag like structure, filled with gas and acting as a float of certain coelenterate.
  55. Polymorphism : The occurrence of at least two, generally many, radically different body forms within colonial or social organisms.
  56. Pre-oral : Means located in front of the mouth.
  57. Pseudocoelom : It is false coelom the body cavity which is not lined by peritoreal lining is called pseudocoelom
  58. Redula : These are chitinous ribbons bearing a number of transverse rows of teeth. These are located on the floor of the buccal cavity of most mollusca.
  59. Scleroblast : It is a type of binucleate cell found in porifera which is responsible for secreting the spicular skeleton.
  60. Scolex : It is the anterior end or “head” of cestodes.
  61. Scutum : A body plate, part of exoskeleton of anthropods.
  62. Seyphistoma : Polyp-like stage in the life cycle of a scyphozoan coelenterate.
  63. Shell beak : It is the oldest part of the shell in a bivalve mollusk at the tip of each valve near the hinge.
  64. Spongin : It is a fibrous seleroprotein that forms a skeleton in some sponges.
  65. Sporozite : Spore produced by multiple fission after sexual reproduction in certain protozoa.
  66. Statocyst : It refers to a resistant body found in Bryozoa.
  67. Symbiosis : It is an association in which two individuals mutually benefit each other.
  68. Terrestrial animals : The animals which live on land are called terrestrial animals.
  69. Torsion : It refers to twisting of the visceral hump or mass found in most gastropods.
  70. Triploblastic animals : The animals which develop from three germinal layers are known as triploblastic animals.
  71. Trochophore : It refers to ciliated larval form found in various invertebrates.
  72. Tube Feet : These are tentacle like outpushing from the water vascular system that may be used for locomotion in Echinodermatea.
  73. Unicellular animal : When the body of an animal is made up of single cells it is called unicellular animal.
  74. Veliger : It refers to the larval form found in the mollusca. It is modified form of the trochophore by the appearance of adult organs and an enlarged cilitated lobe, the velum.
  75. Velum : A narrow fold or ridge which runs around the edge of the umbrella in the medusa of most Hydrozoa. The tentacle are inserted on this ridge.
  76. Viteline Gland : It is a reproductive gland that is found in platyhelminthes and is responsible for secreting the egg shell.
  77. Viviparous : The animals which give birth to young ones.